Abstract: This book prioritises research on threatened species in South Africa so that scarce resources can be most effectively utilised to understand and minimize threats to the diversity of frogs found in this country. The first chapter provides a general introduction on a global and local amphibian decline, with the remaining chapters covering research priorities for taxonomy, conservation, monitoring and public awareness. An appendix was included which provides an update of the Red List with IUCN criteria for all threatened South African amphibians. This document also provides conservation agencies, policy makers and planners with invaluable information on what is required to make a difference to this most threatened group of vertebrates.
Abstract: We conducted a literature review on the current status of all known extralimital populations of the African clawed frog, Xenopus laevis, to identify commonality in invasion pathways, lag between discovery and introduction, and whether old populations are in decline. Further, we investigated which locations are vulnerable to future establishment using geospatial data (1,075 native and 124 invasive records) in a Maxent model developed with data from the Worldclim database. We found introductions of X. laevis to be continuous over the last 50 years and invasions to be ongoing on four continents: Asia, Europe, North and South America. Invasion pathways were related to scientific use and the pet trade, with high rates of deliberate release followed by a lag of 2-25 years to first reports. No populations were found to be declining although some have been extirpated. Optimal uninvaded bioclimatic space was identified in central Mexico and southern Australia, while larger suitable areas were found in southern South America and southwestern Europe. Xenopus laevis is a cryptic invasive species that is likely to increase its invasive distribution, through new introductions and by the spread of ongoing invasions. Many more invasive populations are likely to exist than are currently recognised and reducing invasive potential will largely rely on education of those involved with their captive care.
Abstract: Caecilians are limbless amphibians that have evolved distinct cranial and postcranial specializations associated with a burrowing lifestyle. Observations on feeding behavior are rare and restricted to above-ground feeding in laboratory conditions. Here we report data on feeding in tunnels using both external video and X-ray recordings of caecilians feeding on invertebrate prey. Our data show feeding kinematics similar to those previously reported, including the pronounced neck bending observed during above-ground feeding. Our data illustrate, however, that caecilians may be much faster than previously suspected, with lunge speeds of up to 7?cm?sec-1. Although gape cycles are often slow (0.67?+/-?0.29?sec), rapid jaw closure is observed during prey capture, with cycle times and jaw movement velocities similar to those observed in other terrestrial tetrapods. Finally, our data suggest that gape angles may be large (64.8?+/-?18 degrees) and that gape profiles are variable, often lacking distinct slow and fast opening and closing phases. These data illustrate the importance of recording naturalistic feeding behavior and shed light on how these animals are capable of capturing and processing prey in constrained underground environments. Additional data on species with divergent cranial morphologies would be needed to better understand the co-evolution between feeding, burrowing, and cranial design in caecilians. J. Exp. Zool. 317A:533539, 2012. (c) 2012 Wiley Periodicals, Inc.
Abstract: Convergent evolution can explain similarity in morphology between species, due to selection on a fitness-enhancing phenotype in response to local environmental conditions. As selective pressures on body morphology may be strong, these have confounded our understanding of the evolutionary relationships between species. Within the speciose African radiation of lacertid lizards (Eremiadini), some species occupy a narrow habitat range (e. g. open habitat, cluttered habitat, strictly rupicolous, or strictly psammophilic), which may exert strong selective pressures on lizard body morphology. Here we show that the overall body plan is unrelated to shared ancestry in the African radiation of Eremiadini, but is instead coupled to habitat use. Comprehensive Bayesian and likelihood phylogenies using multiple representatives from all genera (2 nuclear, 2 mitochondrial markers) show that morphologically convergent species thought to represent sister taxa within the same genus are distantly related evolutionary lineages (Ichnotropis squamulosa and Ichnotropis spp.; Australolacerta rupicola and A. australis). Hierarchical clustering and multivariate analysis of morphological characters suggest that body, and head, width and height (stockiness), all of which are ecologically relevant with respect to movement through habitat, are similar between the genetically distant species. Our data show that convergence in morphology, due to adaptation to similar environments, has confounded the assignment of species leading to misidentification of the taxonomic position of I. squamulosa and the Australolacerta species.
Abstract: Aim To determine the spatial relationship between areas where different frog breeding groups occur and elevated anthropogenic activities, and the conservation implications thereof. Location South Africa. Methods Data on frog distribution ranges for the southern African sub-region were used to identify biogeographical areas within South Africa. A random draw technique was used to determine whether areas where different frog breeding groups occur were characterized by higher levels of anthropogenic threats than expected by chance. Four measures (human population density, percentage land transformation, percentage protected area and invasive alien plants richness) expected to reflect threats were analysed. Results Terrestrial-breeders were more often spatially associated with areas of threat than expected by chance in three of the seven biogeographical regions examined with land transformation and invasive alien plant richness being most significant. The south central was the only region where terrestrial-breeders were spatially congruent with protected areas. Areas where stream-breeders occur were spatially congruent with anthropogenic threats (with alien plants being most consistent) in five of the seven regions examined while protected areas were well represented in four of the seven regions. Non-significant results were found for permanent and temporary aquatic-breeders at both the national and the biogeographical scale. Main conclusions By analysing data at the sub-continental scale we were able to identify regional threats to amphibians traditionally classified at species-specific scales. Our study recognized land transformation and alien invasive plants as significant threats to areas important for the long-term breeding success of stream and terrestrial amphibians in South Africa. Areas where different breeding groups occur in the south-western Cape showed the greatest spatial congruence with the threats examined. Areas where terrestrial breeding frogs occur are not well represented in the current conservation network. This has important implications in addressing the current status of threats on amphibians in a biogeographical context.
Abstract: Although reptile diversity in Africa is high, it is poorly represented in Angola, with just 257 species known. Despite its greater surface area and habitat diversity Angola has significantly lower lacertid lizard diversity than adjacent Namibia. This is particularly notable in African sand lizards (Pedioplanis), where 10 species (two endemic) are known from Namibia but only two are recorded from adjacent Angola. Pedioplanis benguellensis was described from Angola, but its taxonomic status is problematic and it was previously synonymised with P. namaquensis. All other Angolan Pedioplanis were referred to Namibian P. undata, although this taxon is now known to comprise a complex of at least five different species and the relationship of Angolan material to this complex has not been assessed. In this study, we investigated the phylogenetic placement of Angolan Pedioplanis using two mitochondrial (ND2 and 16S) and one nuclear (RAG-1) markers. A Bayesian analysis was conducted on 21 samples from Angola, combined with existing data for 45 individuals from GenBank and three additional samples from central Namibia. The phylogeny demonstrates that P. benguellensis is a valid species and that it is not the sister taxon to P. namaquensis with which it has been morphologically confused. In addition, Angolan lacertids previously referred to P. undata are not conspecific with any of the Namibian or South African species in that complex. Rather, there is strong support for the presence in Angola of additional species of Pedioplanis, which form a well-supported sister clade to the P. undata complex (sensu stricto) of Namibia and two of which are described herein. These discoveries highlight the need for further biodiversity surveys in Angola, as similar increases in species diversity in other Angolan taxa might be found given sufficient investment in biodiversity surveys.
Abstract: The dearth of information on caecilian amphibians is most likely due to a lack of directed field studies. Here we report the rediscovery of a population of Boulengerula denhardti nearly a century after its description by Nieden in 1912. Morphological examination of seven specimens suggests that they are closer to the type of B. denhardti than to any other member of the genus. Nieden's type locality has been widely interpreted as the Tana River Delta, although searches there have not revealed specimens of this species. The locality of the material described herein comes from Ngaia Forest, Meru County, Kenya, approximately 420 km, northwest of the Tana Delta. We discuss dispersal in caecilians and their likely use of riverine corridors. We speculate that more species in this genus are likely to be found in Kenya.
Abstract: Toe and tail clipping are commonly used methods for permanent marking of animals and for obtaining tissue samples for genetic analyses. Although it has been tested whether toe clipping affects locomotor performance (and thus potentially the fitness of an individual), little is known about the effect of tail clipping. Tails are important organs in many amphibians and reptiles and are used for balance or stability during locomotion or as prehensile organs. Effects of tail autotomy or the removal of large parts of the tail have previously been demonstrated. Here, we test whether the removal of a small part (<5 mm) of the distal tail in chameleons affects their ability to cling to branches of different diameters by measuring gripping strength using of a force platform. Our data show no significant or directional effect of tail clipping on the maximal forces that can be generated by the tail and, thus, suggest that tail clipping can be used as a method for tissue collection.
Abstract: A new species of African reed frog (genus Hyperolius Rapp, 1842) is described from a high altitude, forested gorge in the Serra da Chela mountain range near the village of Humpata, Lubango area, Huila Province, south-western Angola. It is currently only known from its type locality. Phylogenetic reconstruction using the mitochondrial 16S marker reveals that it is the sister taxon of the poorly known Hyperolius cinereus (>4% sequence divergence) also described from Angola, and forms part of a larger clade comprising H. platyceps. The new species is distinguished from other closely related Hyperolius species by genetic divergence, vocalisation, an unusual torrent stream habitat, and colouration.
Abstract: Aim East Africa is one of the most biologically diverse regions, especially in terms of endemism and species richness. Hypotheses put forward to explain this high diversity invoke a role for forest refugia through: (1) accumulation of new species due to radiation within refugial habitats, or (2) retention of older palaeoendemic species in stable refugia. We tested these alternative hypotheses using data for a diverse genus of East African forest chameleons, Kinyongia. Location East Africa. Methods We constructed a dated phylogeny for Kinyongia using one nuclear and two mitochondrial markers. We identified areas of high phylogenetic diversity (PD) and evolutionary diversity (ED), and mapped ancestral areas to ascertain whether lineage diversification could best be explained by vicariance or dispersal. Results Vicariance best explains the present biogeographic patterns, with divergence between three major Kinyongia clades (Albertine Rift, southern Eastern Arc, northern Eastern Arc) in the early Miocene/Oligocene (> 20 Ma). Lineage diversification within these clades pre-dates the Pliocene (> 6 Ma). These dates are much older than the Plio-Pleistocene climatic shifts associated with cladogenesis in other East African taxa (e.g. birds), and instead point to a scenario whereby palaeoendemics are retained in refugia, rather than more recent radiations within refugia. Estimates of PD show that diversity was highest in the Uluguru, Nguru and East Usambara Mountains and several lineages (from Mount Kenya, South Pare and the Uluguru Mountains) stand out as being evolutionarily distinct as a result of isolation in forest refugia. PD was lower than expected by chance, suggesting that the phylogenetic signal is influenced by an unusually low number of extant lineages with long branch lengths, which is probably due to the retention of palaeoendemic lineages. Main conclusions The biogeographic patterns associated with Kinyongia are the result of long evolutionary histories in isolation. The phylogeny is dominated by ancient lineages whose origins date back to the early Miocene/Oligocene as a result of continental wide forest fragmentation and contraction due to long term climatic changes in Africa. The maintenance of palaeoendemic lineages in refugia has contributed substantially to the remarkably high biodiversity of East Africa.
Abstract: Caecilians remain an enigmatic component of the tropical terrestrial fauna due in part to their cryptic life-history but also to a lack of directed effort towards their study. Many species are known from single specimens associated with poor collection data, which has not facilitated re-collection. Consequently, nearly two thirds of species are currently considered Data Deficient by the IUCN. Boulengerula fischeri was described from a single specimen deposited onto a car by an unknown collector in 1987, and has defied attempts at relocation for nearly 20 years. Herein we describe a collection of 20 individuals from agricultural land immediately outside Cyamudongo Forest in southwestern Rwanda, around 3 km from the type locality. Adults were found to attain a remarkable maximum length of nearly 400 mm despite being only 4.5 mm wide (maximum elongation index of 102). The range of morphometric and meristic measurements taken include those given for the type specimen, featuring mean annular and vertebral counts of 199.4 and 191.8, respectively. The estimated density of B. fischeri was found to be 50 animals h(-1) km(-1) and is comparable with other species of Boulengerula. Despite our new collection records, we recommend that this species remains Data Deficient until its range can be better described.
Abstract: Phylogenetic relationships of the East African caeciliid Boulengerula were reconstructed using 12S, 16S and cytb mitochondrial gene sequences for 32 samples from Kenya and Tanzania. The generally well-supported and resolved phylogeny displayed the following relationships among the five nominate species sampled: (B. boulengeri ((B. taitanus, B. niedeni),(B. changamwensis, B. uluguruensis))). This resolution supports a formerly proposed bipartition of the genus, and differs significantly from previous, morphological phylogenies. Our analyses identified genetic differences between several mtDNA clades that potentially represent undescribed species. If substantiated, the necessary taxonomic revision will have implications for conservation assessments that depend to an important extent upon sizes of distributions. Overall, there is a positive correlation between genetic and geographic distance among and within the main clades. The two lowland, coastal individuals sampled are nested within primarily montane clades. Dating analyses suggest some temporally congruent divergences in Boulengerula, but other divergences happened at different times and over a long period, perhaps extending back to the Oligocene/Eocene. Our results for Boulengerula suggest a role for relative long-term environmental stability in the origins of the Eastern Arc Mountains biodiversity hotspot.
Abstract: Ecologically induced morphological variation has been identified as a mainstay in evolutionary theory. Species that inhabit different habitats are likely to display morphological and functional differences related to the exploitation of different dietary resources available in each habitat within limits imposed by trade-offs. Here, we examine two populations of the Cape Dwarf Chameleon, Bradypodion pumilum, from fynbos (heathland) and woodland to investigate whether head morphology and bite performance are related to diet within and between populations. Stomach contents are compared with prey availability to test whether chameleons are selective with respect to prey size, hardness and evasiveness. Our data show that for adult chameleons from the fynbos (Kogelberg; n = 44), mean and maximum prey size are tightly correlated with head morphology and performance. In woodland habitat (Stellenbosch; n = 52), only maximum prey size is correlated with head morphology and performance. Fynbos chameleons showed no preference with respect to prey hardness, while those from woodland ate less hard and/or sedentary prey than available, thus preferring items that were soft and/or evasive. Finally, fynbos chameleons have a diet of sedentary and/or evasive prey similar in proportions to that available. Our results suggest that diet is not directly related to selection on the head morphology and biting performance of B. pumilum in woodland habitat, but that it may be important for selection in fynbos due to a reduction in overall prey availability.
Abstract: Aim East Africa is one of the most biologically diverse regions, especially in terms of endemism and species richness. Hypotheses put forward to explain this high diversity invoke a role for forest refugia through: (1) accumulation of new species due to radiation within refugial habitats, or (2) retention of older palaeoendemic species in stable refugia. We tested these alternative hypotheses using data for a diverse genus of East African forest chameleons, Kinyongia. Location East Africa. Methods We constructed a dated phylogeny for Kinyongia using one nuclear and two mitochondrial markers. We identified areas of high phylogenetic diversity (PD) and evolutionary diversity (ED), and mapped ancestral areas to ascertain whether lineage diversification could best be explained by vicariance or dispersal. Results Vicariance best explains the present biogeographic patterns, with divergence between three major Kinyongia clades (Albertine Rift, southern Eastern Arc, northern Eastern Arc) in the early Miocene/Oligocene (> 20 Ma). Lineage diversification within these clades pre-dates the Pliocene (> 6 Ma). These dates are much older than the Plio-Pleistocene climatic shifts associated with cladogenesis in other East African taxa (e. g. birds), and instead point to a scenario whereby palaeoendemics are retained in refugia, rather than more recent radiations within refugia. Estimates of PD show that diversity was highest in the Uluguru, Nguru and East Usambara Mountains and several lineages (from Mount Kenya, South Pare and the Uluguru Mountains) stand out as being evolutionarily distinct as a result of isolation in forest refugia. PD was lower than expected by chance, suggesting that the phylogenetic signal is influenced by an unusually low number of extant lineages with long branch lengths, which is probably due to the retention of palaeoendemic lineages. Main conclusions The biogeographic patterns associated with Kinyongia are the result of long evolutionary histories in isolation. The phylogeny is dominated by ancient lineages whose origins date back to the early Miocene/Oligocene as a result of continental wide forest fragmentation and contraction due to long term climatic changes in Africa. The maintenance of palaeoendemic lineages in refugia has contributed substantially to the remarkably high biodiversity of East Africa.
Abstract: Background: The Eastern Arc Mountains (EAM) is an example of naturally fragmented tropical forests, which contain one of the highest known concentrations of endemic plants and vertebrates. Numerous paleo-climatic studies have not provided direct evidence for ancient presence of Pleistocene forests, particularly in the regions in which savannah presently occurs. Knowledge of the last period when forests connected EAM would provide a sound basis for hypothesis testing of vicariance and dispersal models of speciation. Dated phylogenies have revealed complex patterns throughout EAM, so we investigated divergence times of forest fauna on four montane isolates in close proximity to determine whether forest break-up was most likely to have been simultaneous or sequential, using population genetics of a forest restricted arboreal chameleon, Kinyongia boehmei. Methodology/Principal Findings: We used mitochondrial and nuclear genetic sequence data and mutation rates from a fossil-calibrated phylogeny to estimate divergence times between montane isolates using a coalescent approach. We found that chameleons on all mountains are most likely to have diverged sequentially within the Pleistocene from 0.93-0.59 Ma (95% HPD 0.22-1.84 Ma). In addition, post-hoc tests on chameleons on the largest montane isolate suggest a population expansion similar to 182 Ka. Conclusions/Significance: Sequential divergence is most likely to have occurred after the last of three wet periods within the arid Plio-Pleistocene era, but was not correlated with inter-montane distance. We speculate that forest connection persisted due to riparian corridors regardless of proximity, highlighting their importance in the region's historic dispersal events. The population expansion coincides with nearby volcanic activity, which may also explain the relative paucity of the Taita's endemic fauna. Our study shows that forest chameleons are an apposite group to track forest fragmentation, with the inference that forest extended between some EAM during the Pleistocene 1.1-0.9 Ma.
Abstract: Variation in phenotype between species or populations of the same species living in different habitats is often explained in an adaptive context with local habitat differences driving selection on morphological traits relevant in a given ecological context. Previous studies have demonstrated significant differences in limb and tail morphology between populations of the Cape Dwarf Chameleon (Bradypodion pumilum) living in closed vs. open habitats. However, the adaptive nature of the observed differences remains unclear. Here, we quantify the structural habitat use in two different populations, test whether the random habitat differs between the two sites and whether or not chameleons select perches randomly. Next, we test whether morphology is correlated with structural habitat use and test for differences in performance between populations. Our results demonstrate that habitats are structurally different, that chameleons in the two populations use perches of different diameters and that, in one of the populations, chameleons select relatively wider perches than available at random. Performance traits (hand and tail grip performance and sprint speed) are correlated with morphology (hand size, tail length and tibia length) and differ between sexes and populations. Moreover, performance is dependent on dowel size. These results suggest that differences in performance between populations are indeed adaptive and indicate the existence of true ecomorphs in chameleons of the genus Bradypodion. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 692-700.
Abstract: Caecilians are limbless amphibians that have radiated extensively in the tropics, and have evolved distinct cranial and postcranial specializations associated with a burrowing lifestyle. Some species are recognized as being surface active, whereas others are dedicated burrowers. Previous authors have demonstrated that some caecilians use a hydrostatic mechanism to generate burrowing forces which is dependent on the existence of skin vertebral independence. It has been hypothesized that skin-vertebral independence may be lost in extremely elongated species, thus affecting their ability to burrow. Here, we use X-ray video to study the kinematics of locomotion in five species of caecilian differing in their degree of body elongation. Animals were filmed moving in or across different substrates imposing different functional demands on the locomotor system. Our data demonstrate that all species have the ability to perform internal concertina locomotion, but indicate differences between species in the kinematics of locomotion with more elongate species showing a smaller degree of skin-vertebral independence. In all species, locomotion was dependent on the substrate and species switched from using lateral undulation on the surface substrates to the use of whole body or internal concertina in wide and narrow tunnels, respectively. When burrowing in soil, all species used a combination of whole-body and internal concertina locomotion. Additional studies on the ability of different species to generate forces are needed to test whether the reduced skin-vertebral independence in elongate forms has resulted in a decreased ability to generate burrows. J. Exp. Zool. 313A:301-309, 2010. (C) 2010 Wiley-Liss, Inc.
Abstract: Bates, M.F., Pietersen, D.W. & Measey, G.J. 2010. New amphisbaenian records for the Northern Cape, South Africa. Navors. nas. Mus., Bloemfontein 26(3): 61-72. New distribution records are provided for four species of amphisbaenians from Northern Cape Province, South Africa. We report on the third South African locality for Dalophia pistillum, representing the first record of the species from the Northern Cape and the most southerly record for the species. An amphisbaenian from the Kgalagadi Transfrontier Park is tentatively referred to Monopeltis sphenorhynchus and may represent the first record of this species from the Northern Cape, and the most westerly record for the species. Four new localities - including the southernmost record for the species - are provided for Monopeltis mauricei, a widespread species previously known in South Africa from only a few localities and six specimens. Two adjacent new localities are recorded for Monopeltis infuscata, partially filling a large gap in the known range of this species in the Northern Cape. We also report the first known instances in South Africa of parapatry between M. mauricei and M. infuscata, and sympatry between M. mauricei and D. pistillum. South African localities for D. pistillum and M. mauricei are discussed and details corrected where necessary.
Abstract: Traditional models of amphibian dispersal and gene flow point to low dispersal and high philopatry. In recent years, this traditional view has been challenged and it appears that no general model holds across taxa. Conservation of amphibians cannot be addressed on an over-arching scale, but must come on a case-by-case basis, especially for range-restricted species where information on gene flow and migration must be incorporated into conservation efforts. The only two members of the genus Capensibufo Grandison, 1980 (Anura: Bufonidae) are range restricted small bufonids, with distributions limited to montane areas in South Africa. Using a Bayesian analysis of two mitochondrial markers (16S and ND2), we examined the genetic patterns in Capensibufo rosei and Capensibufo tradouwi in order to understand both taxonomic and geographic boundaries. These species were not monophyletic, and demonstrate no clear taxonomic boundaries. Instead, the genus is extremely diverse genetically, with distinct lineages confined to isolated mountains that represent geographic boundaries. In addition, bioclimatic modelling using MAXENT and scenarios of climatic conditions at both the present and last glacial maximum suggest multiple bioclimatic and physical barriers to gene flow at present and in the past. We conclude that members of the genus have very low vagility, that current taxonomic boundaries are inadequate, and that strong geographic structuring has undoubtedly contributed to genetic diversity at the species level, rather than the population level. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 822-834.
Notes: Tolley, Krystal A. De Villiers, Atherton L. Cherry, Michael I. Measey, G. John
Abstract: Reptiles have an amazing diversity of life-history attributes ranging from the shortest- to longest-lived of vertebrate species. Estimating survival in wild populations is of key importance when understanding population dynamics and life-history evolution. However, data are lacking for a large and charismatic group of lizards, the chameleons. We conducted a Robust Design (RD) capture-mark-recapture (CMR) experiment on the Cape dwarf chameleon, Bradypodion pumilum, at two nested sites within the Cape Town Metropolitan Area, South Africa, in order to estimate survival and movement of adults in and around an isolated 3.5 ha patch of suitable habitat. Over a nine-week period, 97 individuals were identified in 379 captures from five primary capture sessions with three secondary events each. Analysis of CMR data provided evidence that smaller chameleons have a substantially lower survival per 10-day period than larger chameleons. RD analysis showed that males were more prone to temporary emigration than females, while open multi-strata analysis revealed that smaller chameleons more readily moved between the sites than larger chameleons. Our findings offer first important insights into chameleon survival and life-history dynamics, which suggest a more vagile subadult population and the possibility of male biased dispersal. Our results have implications for managing the conservation of threatened chameleon populations in highly fragmented urban habitats.
Notes: Tolley, Krystal A. Raw, Robert N. V. Altwegg, Res Measey, G. John
Abstract: The group of forested mountains known as the Taita Hills are the northern-most montane blocks of the Eastern Arc Mountains, a globally recognized biodiversity hotspot They are surrounded by the dry Tsavo plains Until the present study no comprehensive survey of the amphibian fauna of Taita Hills covering the entire altitudinal gradient had been conducted In this study details on the distribution and life history of amphibians associated with montane forest are provided The biodiversity importance of the Taita Hills lies with the number of endemics per unit of area of remaining forest, which is one of the highest among the Eastern Arc Mountains Presented herein are data for these endemics and other amphibian species associated with montane forest based on our field surveys from 2005 to 2007 In addition we have included published data and those from previous collections housed at the National Museums of Kenya, Nairobi The results indicate that the majority of the twenty-six amphibians species recorded from the Taita Hills are those of the widespread East African lowland fauna Only six are those associated with montane forest, including three threatened endemics Concern is raised for the protection of this endemic amphibian fauna associated with montane forest because of ongoing habitat degradation
Abstract: A new species Callulina dawida is described from the Taita Hills, Kenya. It is distinguished from other members of the genus on the basis of the degree of digital expansion. The species further differs from other members of the genus based on molecular sequence comparisons and on its call. The morphological variation in the new species is described, including a comparison of internal and external characters and sexual dimorphism with other species of Callulina. The conservation status of the species, on the basis of its restricted distribution and land use changes in the area, is considered to be of high concern. An updated key of the species of Callulina is provided.
Notes: ISI Document Delivery No.: 452UA xD;Times Cited: 0 xD;Cited Reference Count: 15 xD;Loader, Simon P. Measey, G. John De Sa, Rafael O. Malonza, Patrick K.
Abstract: Biodiversity hotspots are centres of endemism and thus contain many range-restricted species. In addition, within these hotspots occur widespread species that might have originated within a hotspot before dispersing to neighbouring or distant regions. We test this hypothesis with a phylogeographic analysis of a miniature leaf litter frog, Arthroleptis xenodactyloides, that has a large distribution throughout the Eastern Arc biodiversity hotspot and other regions in East Africa. Maximum-likelihood and Bayesian estimates of the mitochondrial gene phylogeny are used as a proxy for understanding the evolutionary history of diversification and the historical relationships between populations. The north-south range of this species extends for approximately 1900 km; our sampling covers approximately 85% of this range. Using phylogenetic comparative methods, we estimate the region of origin and direction of dispersal within A. xenodactyloides. We compare contrasting hypotheses of latitudinal range expansion using bayes factors. The ancestral region of origin of A. xenodactyloides is reconstructed as having occurred within the Eastern Arc before dispersing southwards into the southern Rift Mountains, probably in the Pleistocene. The phylogeographic structure within this leaf litter frog is surprisingly similar to that of forest birds, revealing that similar geographic features might have had a driving role in diversification of these very dissimilar taxa. Latitudinal expansion occurred early in the evolutionary history of A. xenodactyloides, which may indicate that physiological adaptation facilitated its wide geographic distribution.
Notes: ISI Document Delivery No.: 433FJ xD;Times Cited: 3 xD;Cited Reference Count: 72 xD;Blackburn, D. C. Measey, G. J.
Abstract: The evolution of ecomorphs within a species may represent either unique evolutionary events or multiple convergent events in similar environments. Functional studies of differing morphological traits of ecomorphs have been important to elucidate their role in adaptive radiations. The Cape dwarf chameleon, Bradypodion pumilum, has two ecomorphs: a large, brightly colored, ornate form found in closed habitats, and a small, dull form with reduced ornamentation found in open vegetation. The typical form is known to use casque size to communicate fighting ability, but it is unknown whether this is an honest signal and whether casque size is related to bite force. We show through a population genetic analysis that these ecomorphs are not separate genetic lineages but the result of multiple transitions between closed and open habitats. From measurements of ornamental and non-ornamental morphological characters and bite force in 105 chameleons, we find that bite force is significantly related to head size and is best predicted by head width. Bite force was reasonably predicted by casque height in ecomorphs from closed habitats, but not in those from open habitats. For size-adjusted data, open habitat males had wider heads, biting harder than closed habitat males. Our data suggest honesty in signaling for closed habitat ecomorphs, but for open habitat ecomorphs communication is different, a finding commensurate with the common framework for species radiations. (c) 2009 Elsevier GmbH. All rights reserved.
Notes: ISI Document Delivery No.: 439YG xD;Times Cited: 1 xD;Cited Reference Count: 44 xD;Measey, G. John Hopkins, Kevin Tolley, Krystal A.
Abstract: Subterranean herpetofauna comprise an estimated 20% of the world's amphibians and reptiles but are one of the least studied groups of terrestrial vertebrates. Monitoring population trends and threats to these species is dependent in part on quantitative historical data, which are generally lacking. One exception is a 1970 study conducted in Ndumu Game Reserve, South Africa. We revisited this area in 2004 and carried out comparative quantitative sampling in deciduous broad-leaf woodland and sand forest habitats. Our results show a 79% reduction in density of subterranean herpetofauna, as well as a reduction in diversity. Mann-Whitney tests show that the amphisbaenian Zygaspis vandami has undergone a significant reduction in density in both habitats sampled. We relate reductions in subterranean herpetofaunal densities to an increased density of the Reserve's ungulate grazers, suggesting a link between reduction in leaf-litter and soil macrofauna prey of the fossorial reptiles. This study highlights the need for quantitative surveys of subterranean herpetofauna to support future conservation efforts.
Notes: ISI Document Delivery No.: 450WR xD;Times Cited: 0 xD;Cited Reference Count: 15 xD;Measey, G. John Armstrong, Adrian J. Hanekom, Catharine
Abstract: The proximate functions of animal skin colour are difficult to assign as they can result from natural selection, sexual selection or neutral evolution under genetic drift. Most often colour patterns are thought to signal visual stimuli; so, their presence in subterranean taxa is perplexing. We evaluate the adaptive nature of colour patterns in nearly a third of all known species of caecilians, an order of amphibians most of which live in tropical soils and leaf litter. We found that certain colour pattern elements in caecilians can be explained based on characteristics concerning above-ground movement. Our study implies that certain caecilian colour patterns have convergently evolved under selection and we hypothesize their function most likely to be a synergy of aposematism and crypsis, related to periods when individuals move overground. In a wider context, our results suggest that very little exposure to daylight is required to evolve and maintain a varied array of colour patterns in animal skin.
Notes: ISI Document Delivery No.: 434CF xD;Times Cited: 0 xD;Cited Reference Count: 94 xD;Wollenberg, K. C. Measey, G. John
Abstract: Very little life-history information is available regarding the 13 species of earless dwarf toads from the genus Mertensophryne. We report our observations on the breeding behaviour of M. taitana from Mount Mbololo in the Taita Hills, Kenya. Empirical data from pit-fall trapping suggest that they are not abundant in the area (<1.5% of captures), although we managed to batch mark 230 individuals from breeding assemblages in road puddles during 20 days in November 2007. Results reveal that most individuals depart from a breeding site within 24 hours, although some (around 10%) remain while others travel up to 100 m to nearby puddles. Despite their lack of columellae, these dwarf toads appear to react to conspecific distress calls. Eggs develop rapidly into tadpoles and toadlets within 15 days of being laid, but tadpoles were not observed to use their "crown" at the water surface as previously reported. Instead they were observed submerged in liquid mud at the periphery of puddles. Our brief observations on this species suggest that conservation assessments on threatened members of the genus may be problematic, and we highlight the paucity of natural-history information on dwarf toads in general.
Notes: ISI Document Delivery No.: 478TY xD;Times Cited: 0 xD;Cited Reference Count: 22 xD;Ngwava, Jacob Mueti Malonza, Patrick K. Measey, G. John
Abstract: Amphibian spermatogenic cycles are best known from mass breeding anurans and urodeles which have annual cycles featuring both active and quiescent periods. Spermatogenesis of caecilian amphibians is less well known, but recent studies have revealed similar annual cycles for tropical Indian species which have aquatic larvae. Here we report our findings for a direct-developing, oviparous caeciliid from the Taita Hills, Kenya. We investigated the testes of a year-round collection of Boulengerula taitanus Loveridge 1935 using morphological and histological testicular features to determine the size at maturity and presence of seasonal activity in this species. Testes volume, but not number, was directly related to total body volume, and a slight but significant asymmetry was found. Histological investigations revealed active spermatogenesis throughout the year, with subtle seasonal variations which are described. The smallest male showing signs of active testes was 227 mm long while the proportion of testes to body volume increased dramatically between 220 and 240 mm total length. This is the first caecilian to be examined which shows year round spermatogenic activity with no regression or recrudescence of the testes. Our study highlights the paradox between clearly seasonal female reproductive activity and continuously spermatogenically active males. This in turn prompts questions concerning the decoupling of mating and egg-laying in this and other caecilian species.
Notes: ISI Document Delivery No.: 342WB xD;Times Cited: 2 xD;Cited Reference Count: 35 xD;Measey, G. J. Smita, M. Beyo, R. S. Oommen, O. V.
Abstract: Amphibians are in decline worldwide, and high altitude tropical areas appear to be the worst affected. This is in stark contrast with current information we have on gene flow in amphibian populations which focus on temperate pond breeding species. Using AFLP markers, we show that a small, direct-developing, leaf litter frog from the Taita Hills in south-west Kenya (Schoutedenella xenodactyloides) has extended populations covering large areas (> 3.5 km) of fragmented, forest habitat, uncharacteristic of typical amphibian models. Further, we demonstrate high levels of gene flow (F-ST < 0.065) through unsuitable dry savannah habitat which might otherwise be considered a barrier to dispersal. Landscape genetic analysis demonstrates a strong link between hydrologic features, and further highlights links between sites through specific catchments. We propose a model of passive-active dispersal for the Dwarf Squeaker, S. xenodactyloides, which features passive downhill and active uphill movements over large areas, contrasting with limited cross slope movements. Our study highlights the importance of the diverse reproductive strategies of the Amphibia when considering dispersal and gene flow, and hence conservation management.
Notes: ISI Document Delivery No.: 201RQ xD;Times Cited: 7 xD;Cited Reference Count: 67 xD;Measey, G. J. Galbusera, P. Breyne, P. Matthysen, E.
Abstract: Aim Amphibians are a model group for studies of the biogeographical origins of salt-intolerant taxa on oceanic islands. We used the Gulf of Guinea islands to explore the biogeographical origins of island endemism of one species of frog, and used this to gain insights into potential colonization mechanisms. Location Sao Tome and Principe, two of the four major islands in the Gulf of Guinea, West Africa, are truly oceanic and have an exceptionally high biodiversity. Methods Mitochondrial DNA is used to test the endemic status of a frog from Sao Tome and compare it with congeneric taxa from tropical Africa. Existing data on surface currents, surface salinity, atmospheric circulation and bird migration in the Gulf of Guinea are summarized to address hypotheses concerning colonization mechanisms. Results The endemic status of Ptychadena newtoni (Bocage) is supported here by mitochondrial DNA sequences, and analysis of this and other molecular data indicates that an East African species close to Ptychadena mascareniensis (Dumeril and Bibron) is its nearest relative. We refute the possibility that this population was anthropogenically introduced, in favour of a natural dispersal mechanism. Main conclusions With six endemic frogs and one caecilian, the Gulf of Guinea islands harbour a diverse amphibian fauna. Five of these species appear to have their closest relatives in East Africa. Insufficient evidence exists for transportation by storms, birds or rafts alone. However, we propose a synergy of rafting, favourable surface currents and a reduction in salinity of surface waters. Catastrophic events, or wet periods in climatic history, could allow freshwater paths to open far enough to enable continental flora and fauna to reach these and other isolated oceanic islands.
Notes: ISI Document Delivery No.: 116GN xD;Times Cited: 20 xD;Cited Reference Count: 100 xD;Measey, G. John Vences, Miguel Drewes, Robert C. Chiari, Ylenia Melo, Martim Bourles, Bernard
Abstract: The use of automated grape harvesters in the Cape Wine Growing region has resulted in controversy regarding their effect on the chameleon Bradypodion pumilum. We investigated densities of B. pumilum during harvesting at a vineyard near Stellenbosch, South Africa. During dedicated surveys, no chameleons were found in vines, while vegetation surrounding the vines contained densities as high as 1.3 chameleons per 100 m of survey. In addition, the force required to remove ripe grapes was investigated and found to be substantially lower than that required to dislodge a chameleon. We conclude that the effect of automated grape harvesting on chameleons is negligible.
Notes: ISI Document Delivery No.: 186WR xD;Times Cited: 1 xD;Cited Reference Count: 2 xD;Tolley, Krystal A. Measey, G. John
Abstract: Question: Do caecilians follow Bergmann's rule? Hypothesis: Bergmann's rule explains the wide variation in body sizes found among populations of the terrestrial caecilian Schistometopum thomense. Field site: This is a range-wide study incorporating most terrestrial habitats throughout the island of Sao Tome in the Gulf of Guinea. Methods: We performed morphological measurements on 95 museum specimens and 187 field-collected individuals and compared them with site data from 13 separate localities on the island. Conclusions: This is the first example of a caecilian amphibian that follows Bergmann's rule. Total body mass doubles and length increases by nearly 50% up to 1050 in of altitude. This result is surprising as it occurs virtually on the equator, over a very small spatial scale (< 16 km horizontal), and within a relatively small temperature range (< 10 degrees C).
Notes: ISI Document Delivery No.: 089UL xD;Times Cited: 3 xD;Cited Reference Count: 41 xD;Measey, G. John Van Dongen, Stefan
Abstract: Soil herpetofauna biodiversity is conservatively estimated as 2775 species, made up of 10% and 28% of Amphibia and Squamata, respectively. Neglect in their taxonomy, ecology and standard sampling methodologies suggests that proportions, as well as numbers, are likely to be far higher. Like invertebrate soil macrofauna, the majority of species live within the first few centimetres of leaf litter and soil. Results of 30 quantitative and 52 semi-quantitative surveys in nine regions of three continents show that these are infrequently encountered, whereas dedicated subterranean burrowers can be found at high densities, up to 0.844 individuals m(-2) ((x) over bar = 0.26). This suggests that a two tier sampling approach may be most appropriate, with superficial excavations in a large quadrat (e.g. 25 m(2)) in addition to a smaller deeper subsample. It is hoped that this contribution will stimulate further discussion towards a consensus, filling the gap for a standard method of quantitative surveying of soil herpetofauna biodiversity. (c) 2006 Elsevier Masson SAS. All rights reserved.
Notes: ISI Document Delivery No.: 122YP xD;Times Cited: 3 xD;Cited Reference Count: 29 xD;Measey, G. J. xD;Suppl. 1
Abstract: The African clawed frog, Xenopus laevis, is an invasive species with considerable impact in mediterranean climates, similar to its native South African Cape. A population has been established in western France since the early 1980s with a single. known, original release point. This study attempts to determine the limits of the invasion by trapping in 169 ponds in 2001 and 2002. Subsequent trapping of 192 ponds in 2003 and 2004 was undertaken in order to chart the progress of invasion, and to test the hypothesis that ponds were mostly colonised using rivers and streams as corridors. Of ponds without X. laevis in 2001/2002, 36% were found to have been colonised by 2003/2004. The findings clearly show that, while lotic corridors are used by this principally aquatic species, most ponds are colonised through overland migration. The consequences of this finding for invasions in France and other European countries are briefly discussed.
Abstract: Many animals undergo migrations that depend on a range of biotic or abiotic factors provoking daily, seasonal or annual movement of individuals and/or populations. Temperate amphibians frequently have their life cycles dominated by annual temperature fluctuations, but in the tropics it is often presumed that distinct rainy seasons will influence amphibians more than small changes in temperature. Here, we direct the seasonal changes in abundance hypothesis to a caecilian amphibian Boulengerula boulengeri found in monthly randomized quantitative surveys in the top 30 cm of soil. Meteorological data are used to interpret the significant changes found in relation to rainfall and temperature variables. Instead of the expected correlation of migration with rainfall, we find that frequency varies significantly and positively with temperature. In addition, data on the depth at which individual caecilians are collected suggest that animals undergo a vertical (rather than horizontal) migration within the soil. This is the first example of vertical migrations with temperature (as opposed to rainfall) of any tropical subterranean fauna. We discuss the possible influences that stimulate migration in this species (abiotic factors, feeding, reproduction and predation). The ecology of caecilians has lagged behind that of all other tetrapods, and this study has importance for future ecological studies, as well as biodiversity assessments and monitoring methodologies.
Abstract: It has taken time for the international community to accept the idea of biodiversity values, a concept which had previously been restricted to the limited aesthetic and touristic aspects of wildlife. This situation changed following the International Convention on Biodiversity in Rio de Janeiro (1992), which focussed on "the forgotten environmental problem" of biodiversity erosion and made the first clear reference to the values of living species. Biodiversity values refer to direct or indirect, economic or non-economic interest, a given species or ecosystem may represent for human populations. These values are generally split into intrinsic and instrumental (use) values, the last category itself being divided into direct and indirect economic values. Obviously, each of these values carries different weights, and cannot be considered as being weighted-equally in terms of justification for species or ecosystem conservation. Soil is probably one of the most species-rich habitats of terrestrial ecosystems, especially if the definition is extended to related habitats like vertebrate faeces, decaying wood, and humus of hollow trees (i.e. epiphytic soils). The diversity of soil communities (sensu lato) thus probably encompasses a large part of terrestrial animals. This highly speciose fauna has been the subject of recent research efforts, and current trends in soil fauna studies include aspects of biology, autecology, ecotoxicology, or functional ecology. During the past 20 years, recognition of the importance of soil fauna in the functioning of soils and by extension of terrestrial ecosystems has been continuously growing, ending in some important applications in agronomy. However, despite the general agreement about the ecological importance of soil fauna and its economic consequences, the absence of concern about this group from conservationists in their studies is conspicuous. This paper aims at presenting soil fauna within the scope of conservation biology concepts, trying to identify the different values of soil fauna and how they participe to the provisioning of key ecosystem services. Finally, the enormous gap between their recognised usefulness and their consideration in protection policies is discussed. (c) 2006 Elsevier Masson SAS. All rights reserved.
Notes: ISI Document Delivery No.: 122YP xD;Times Cited: 5 xD;Cited Reference Count: 126 xD;Decaens, T. Jimenez, J. J. Gioia, C. Measey, G. J. Lavelle, P. xD;Suppl. 1
Abstract: Caecilians are a poorly known group of amphibians with a highly derived skull and cranial musculature that has evolved in response to their specialized head-first burrowing lifestyle. They possess a unique jaw-closing system, which is shown to be capable of generating considerable bite forces for its head width ( 1.09 +/- 0.34 and 0.62 +/- 0.31 N for Schistometopum thomense and Boulengerula taitanus, respectively). However, comprehensive dietary studies indicate that there is no need for large bite forces, since most caecilians appear to be generalist predators of subterranean macrofauna. Here, we demonstrate, based on in vivo external and X-ray video recordings of animals feeding, that long-axis body rotations are used independent of prey size by these two species of caeciliid caecilians when feeding underground. Further, we show that individuals are capable of generating a substantial spinning force, which is greater than their bite force ( 1.35 +/- 0.26 and 1.02 +/- 0.18 N, respectively). These observations shed light on the functional and the evolutionary significance of several unique features of the cranial design in derived caecilians; spinning may allow the individuals to judge prey size and subsequently reduce oversized prey within gape limits.
Notes: ISI Document Delivery No.: 114SS xD;Times Cited: 5 xD;Cited Reference Count: 16 xD;Measey, G. John Herrel, Anthony
Abstract: Boulengerula uluguruensis is a terrestrial caeciliid caecilian described from the Uluguru Mountains of Tanzania. We investigated the relative abundance of B. uluguruensis in agricultural and forested habitats at the beginning of the rainy season. This caecilian was found over a wide altitudinal range (450-1175 m a.s.l.), and in many land cover types (including natural forest, plantation forest and small scale agriculture), and different soil textures (including very compact soil). Based on quantitative and semi-quantitative surveys, B. uluguruensis is more abundant than any other subterranean lower vertebrate in this area, with densities up to 0.4 individuals m(-2) in some agricultural plots. The hypothesis proposed, that B. uluguruensis is more abundant in agriculture than their native forest, could not be conclusively tested during this brief visit, although the data that were collected do not indicate to the contrary. Likewise, the size of animals from forest and agricultural populations could not be objectively compared.
Abstract: The relationship between externally measured condition (mass x length(-3)) and the mass of internal major organs in the caecilian Gegeneophis ramaswamii is investigated, based on a collection of 67 specimens from three southern Indian localities in the early and mid-monsoon. Condition in juveniles (< 90 mm total length) is higher than in subaclults (90-170 mm) and adults (> 170 mm). The relationship between condition and total length is consistent in subadults, but variable in adults, and these differences indicate that the delimitation of these ontogenetic stages has some biological meaning. Adult females have fat bodies which fluctuate in mass, but not in relation to their body size. On average, adult females have heavier fat bodies and lighter gut contents than adult males, but there are no significant differences between subadult males and females. Gravid females are predicted to have a notably greater condition. There is no consistent relationship between condition and any major internal organ, but there is some significant variation among samples grouped by sampling time and locality. More sampling throughout the year is required to clarify the complex relationships between condition and internal organs, and before externally measured condition from ecological studies of living animals can be readily interpreted. However, its utility in helping to differentiate between ontogenic classes may be of immediate use.
Abstract: The life histories of amphibians are considered to be well recorded and are frequently regarded as the model complex life history for vertebrates. However, only the most basic information exists for caecilians. Boulengerula taitanus Loveridge 1935 is a direct developing terrestrial caecilian commonly found in agricultural settings of the Taita Hills, Kenya. During 12 monthly visits we collected 239 caecilians by digging into soil. Caecilians were captured on every visit, although increased searching time and low capture numbers coincided when soils were dry. The condition index (ML-3) defines three ontogenetic stages, for which growth can be approximately followed over the sampling period through frequency histograms. Juveniles (< 140 mm) appear to become subadults (< 240 mm) around a year after hatching, while subadults mature into adults (> 240 mm) after a further year. Adult males are significantly longer than females. Mating occurs in the soil prior to egg laying at the beginning of the short rains. Females construct a chamber before laying eggs ((x) over bar = 5), and are found attending eggs during incubation and after hatching. Juveniles make up the smallest proportion of the population (maximum 24% in April and May). Information produced during this study is used to develop a tentative life-table for this species.
Abstract: Invasive populations of anurans contribute to global amphibian declines, and many instances involve pipid frogs. Here we report on an invasive population of Pipa parva in Carabobo State, and a native population in Zulia State, Venezuela. The frogs were found in high densities in a fish farm near Lake Valencia, and had a diet of benthic invertebrates. Invasive P. parva were large compared to those described in previous reports (mean snout-vent length: 37.34 +/- 0.73 mm), but the native population was found to be significantly longer (mean snout-vent length: 44.08 +/- 1.34 mm). Colonisation by terrestrial movement and potential impact of this invasive species are discussed.
Abstract: A new species of East African caeciliid caecilian, Boulengerula niedeni spec. nov. (Amphibia: Gymnophiona) is described based on a series of 11 specimens from Sagalla Hill, an isolated mountain block of the Taita Hills in southern Kenya. It differs from all other Boulengerula, except B. taitanus (Loveridge), in being pigmented with whitish marked annular grooves and from B. taitanus by its distinctive brownish colouration, an exposed sphenethmoid, a higher mean number of annuli and vertebrae, and different phallus morphology.
Abstract: The tadpole of Bufo taitanus is described from material recently collected at the type locality. Tadpoles of B. taitanus possess a crownlike structure on top of the head. Observations suggest that the crown likely acts as an accessory respiratory organ. Development in B. taitanus is rapid with metamorphosis completed after just 13 days. Based on its similarity to tadpoles of Stephopaedes anotis and Mertensophryne micranotis, a close phylogenetic relationship between these three taxa is proposed.
Abstract: Most caecilians are thought to be generalist predators of soil ecosystem engineers (earthworms, termites and ants), but it has been suggested that members of the East African genus Boulengerula are specialist predators. Surprisingly, in the only detailed study of diet of any Boulengerula, the authors speculated that B. taitanus is partly detritivorous, based on the large amount of organic matter found in the alimentary canal. Here we test the conflicting hypotheses that B. taitanus is a termitivore or detritivore, using the stomach and gut contents of 47 specimens collected in the Taita Hills, Kenya. Termites and earthworms contribute most significantly to diet by number and mass, respectively. These constitute the major dietary items, together with dipteran larvae and other soil macrofauna. Contents of the intestine are mostly soil and organic matter originating from prey items. The mass content of the intestines averages 69% of total gut contents, and is significantly greater than identifiable stomach contents. The null hypotheses that B. taitanus is a generalist and a predator are not rejected.
Abstract: Determination of the proximate cause of sexual dimorphism remains difficult, especially when trying to discriminate between sexual selection and ecological causation. A clear rejection of one of these hypotheses would advance the direction of future investigations, especially for cryptic and/or subterranean species. Sexual dimorphism in head size, but not body size, is confirmed for Schistometopum thomense, a fossorial caecilian from the island of S (a) over tilde $o Tome, in the Gulf of Guinea. However, a quantitative and qualitative study of diet reveals no significant difference between males and females sampled from three sites on the island. Females appear to take larger and heavier prey (principally earthworms) than males, despite having a significantly smaller head size. We tentatively reject the ecological causation hypothesis, and discuss several testable hypotheses for evidence of sexual selection.
Abstract: Biologists have paid relatively little attention to subterranean predators, especially their ecology. although diets of some subterranean lower vertebrates suggest specialisation, there remains a lack of quantitative data. The diet of the caecilian amphibian Gegeneophis ramaswamii was investigated through analyses Of gut contents of 67 specimens collected in randomised surveys at three localities in Kerala, Southern India, in early and mid-monsoon. Although termites were the most frequently ingested items in the mid-monsoon. the specialist predator hypothesis was rejected because of differences in diet found in early monsoon samples, when earthworms contributed the greatest mass. That guts of some G. ramaswamii contained many individuals of only a single dietary taxon was interpreted as feeding on patchily distributed prey rather than specialisation. No ontogenetic differences in diet were apparent, but more sampling is required to investigate this further. Subadults largely feed on fewer items of the same prey as adults, though there is an indication that subadult diet is less diverse. The data do not support differences between male and female diet. High densities of G. ramaswamii, and perhaps of other terrestrial caecilians and subterranean lower vertebrates feeding on soil-ecosystem engineers (termites, earthworms and ants), might substantially impact soil ecology.
Abstract: Chthonerpeton indistinctum is nontropical, and reports suggest a distinct breeding season, allowing the potential for estimation of reproductive success. A total of 67 juvenile (and four adult) C. indistinctum were captured over five visits to a site in Rio Grande do Sul, Brazil, during Winter 2001. All individuals were marked and released, and the seven juveniles recaptured allowed a Schnabel estimate of 161.0 (95% confidence limits 81.9-343.1), the first quantitive estimate of juvenile caecilian abundance. However, the large size range of juveniles caught suggests that growth rates of individuals are highly variable or that C. indistinctum does not have a distinct breeding period in this region.
Abstract: Xenopus laevis (Daudin, 1802) has been the subject of numerous studies but is taxonomically poorly understood. Part of the Cytochrome b gene in mitochondrial DNA was sequenced from 50 individual Xenopus from three currently recognised species, taken from 28 localities in southern Africa, and from an outgroup of two West African X. epitropicalis. Phylogenetic analyses of these data reveal well-supported tree structure, demonstrating three clades within what is currently regarded as X. laevis: X. L laevis from the Cape, X. l. petersii, and X. l. laevis from further north. This evidence agrees with other studies (on morphology, call and parasite data) which suggest that what is currently regarded as X. laevis encompasses more than one species. Workers using Xenopus collected away from the Cape of South Africa are not safe in assuming that they are using X. laevis.
Abstract: The potentially important ecology of subterranean predators of soil ecosystem engineers is poorly understood. This is especially true of caecilian amphibians (Gymnophiona) for which there are virtually no quantitative data. Results of the first field trials of permanent marking in caecilians are presented. A preliminary assessment is made of the efficacy of mark-recapture studies for estimating population size of Gegeneophis ramaswamii Taylor in 100 m(2) of low intensity agriculture in Kerala, India. Over three sampling occasions spanning 58 days of the monsoon season, 114 individuals were captured, 104 marked and released, and 21 recaptured. Models estimate an open population of 60 individuals (95% confidence interval of 45.2 to 151.3), and a closed population of 236 (95% confidence interval of 174 to 351). A census interpretation of the raw capture data gives densities of about 0.31 to 0.48 m(-2). Results suggest large movement in and out of the sampled area during the study. Despite caveats associated with these data, progress is made in identifying potential limitations and improvements in the methods used. This study highlights the paucity of knowledge of caecilian ecology, and the need for long-term studies to elucidate further ecological information and to monitor populations.
Abstract: Many subterranean, limbless reptiles and amphibians are predators of invertebrate soil ecosystem engineers. The potential importance of these predators in soil ecology partly rests on whether they occur in high densities, but their abundance has rarely been measured, and there are no standard methods. The mostly tropical and fossorial caecilians (Amphibia: Gymnophiona) are often considered rare, but there are very few quantitative data, and some species, including Gegeneophis ramaswamii, have been reported as abundant in some situations. Using simple and repeatable survey methods with randomised 1 m(2) quadrats, surveys of G. ramaswamii were conducted at five localities in southern India. Densities of 0-1.87 m(-2) per survey were measured, with means of 0.51 and 0.63 m(-2) at the beginning and middle of monsoon, respectively. These densities were far greater than for sympatric caecilians (ichthyophiids; uraeotyphlids) and fossorial snakes (typhlopids; colubrids). While ecological data remain very scant, establishing quantitative methods to assess the abundance of endogeic limbless vertebrates is an important step toward greater understanding of subterranean predator-prey relations, and of monitoring populations of these poorly known organisms. (C) 2003 Elsevier Science B.V. All rights reserved.
Abstract: Invasive populations of Xenopus laevis are known from the UK, USA and Chile, although there is poor documentation of the latter. Currently, four administrative Regions in Chile are reported as having established populations. Fieldwork during the austral winter of 2001 was conducted in order to assess the density and diet of X laevis populations in two localities. At one site, fewer than 30 adults were captured and a population 4 times this size was estimated. At the second site, nearly 2000 adults were trapped and a population of nearly 20 000 was estimated. This yielded density estimates of 0.37 and 0.25 clawed frogs m(-2) respectively. However, significant bias in the sex ratio of animals caught at each site suggests that the populations may be even larger. Stomach contents of a sub-sample of animals revealed a diet consisting primarily of zoobenthic and zooplanktonic components. Further work is required to assess the extent to which this anuran affects the biodiversity of indigenous aquatic invertebrate, fish and amphibian populations.
Abstract: A feral population of African clawed frogs Xenopus laevis from a small pond in South Wales was sampled continuously for 2 years to assess morphometric growth. Toe-clips taken at intervals over a 4-year period were found to contain lines of arrested growth (LAG) which corresponded to each consecutive winter. The first toe-clips revealed a population structure within the pond consisting of a dominant cohort of frogs with one LAG that metamorphosed in 1993, and a few older individuals. Subsequent toe-clips in 1996 and 1998 gave two and four more LAG, respectively. Morphometric growth was found to be restricted to a short growing season, significant differences in the growth rates of males and females being first detected in their third growth season. Reproductively active frogs were still within their initial period of growth, suggesting that Xenopus laevis does not conform to the standard energy resource allocation mechanisms of typical ectotherms.
Abstract: In 1998 and 1999 we conducted investigations of poorly known, soil-dwelling caecilian amphibians of the southern region of the Western Ghats, a recognized biodiversity hotspot, Gegeneophis ramaswamii was widely encountered in varied habitats between sealevel and 600 m, south of 08 degrees 58'N and west of 77 degrees 24'E, It was the most common caecilian species found here, and in two localities densities ranged between 0.44 and 1.13 individuals, and 2.59 and 5.5 g per m(2). This indicates that, contrary to many reports, caecilians are highly abundant in some localities, and that the ecological consequences of this demand investigation.
Abstract: African clawed frogs (Xenopus laevis) in a South Wales pond ate a wide variety and size range of prey. Zoobenthos and zooplankton made the greatest contribution to diets, both numerically and by weight. Terrestrial invertebrates made up a small proportion of the diet numerically but a large proportion of the diet mass during the spring and summer. Nektonic prey were present throughout the year but made up a very small proportion of diet. Cannibalism was important when eggs and larvae were present in the pond. Electivity values were consistently positive for chironomids (larvae and pupae) and daphnids but were consistently negative for tubificids. In addition, electivity increased for larger sizes and pupae of Chironomus plumosus, but was low for the largest size class (> 12 mm). Electivity of other taxa showed an increase when densities of chironomids and daphnids were reduced. Mean sizes of daphnids and cyclopods were consistently larger in frog stomach contents than in the water column, indicating that predation on zooplankton by Xenopus laevis is size-selective.
Abstract: Despite its prominence as the "standard laboratory amphibian", the ecology of the African clawed frog, Xenopus laevis, has been neglected. Feral populations have been documented in several countries with Mediterranean climates, but established populations are also known from the UK. Long term studies of individually-marked X. laevis in South Wales reveal large demographic fluctuations and the ability to migrate overland. Maximum longevity recorded from recapture of marked individuals was 14 years. Diet analysis demonstrates a major reliance on benthic invertebrates and zooplankton components of the pond fauna. Skeletochronological studies of growth rings in bone showed that lines of arrested growth are formed annually and allow calculation of age. Data on population age structure indicate successful recruitment is infrequent, with dominant cohorts originating in perhaps only four summers during the past 20 years.
Abstract: 1. The effects of addition of juvenile perch (Perca fluviatilis) on the microcrustacean and rotifer communities associated with nymphaeid beds were studied, at three different plant densities [high (normal), medium (reduced by a half) and low (reduced to a third of normal)], in eighteen 2 m x Im enclosures in a shallow lake. 2. At the low and medium densities of lilies, Daphnia densities were high in the absence of perch but very low in the presence of perch. They increased, even in the presence of perch, to high densities (comparable with those in the absence of perch) at the highest plant density. Body sizes of Daphnia hyalina were consistent with high predation by perch at low and medium plant densities but reduced predation at high plant densities. Patterns of chlorophyll a concentration, in the presence of perch, inversely reflected those of D. hyalina density. 3. At naturally high densities but not at reduced densities, the plants appeared to act as refuges against predation for the Daphnia. Reductions in oxygen concentrations in the plant beds were not responsible for the refuge effect, nor could there be avoidance of the beds by the fish. The mechanism of the refuge effect must therefore lie in frustration of the process of capture of the Daphnia by the fish. 4. Numbers of other small Crustacea and rotifers were mostly unaffected by fish predation. Numbers of Asplanchna sp., Chydorus sphaericus and copepodites were higher in the presence of fish and, although there was no main effect of fish on numbers of Diaphanosoma brachyurum, there was a plant-fish interaction, with this species being less abundant in the presence of fish at low plant densities but more abundant in the presence of fish at medium and high plant densities. Main effects of plants were few, with only Asplanchna sp. and Keratella sp. decreasing in numbers with increasing plant density. Most taxa changed in numbers with time but interaction effects between time and plants, and fish and plants, were few.
