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Jan C Malmgren

JM Natur
Conservation &
Restoration Ecology

Blåsippestigen 4
SE-432 36 Varberg

Jan C Malmgren (1967-) has a PhD in Ecology and is the founder of JM Natur, specializing in independent research and applied projects in the field of conservation and restoration ecology. He is based in Sweden and has been stationed at Örebro University and the University of Göteborg. Jan is widely experienced in ecology and conservation from both theoretical and applied projects, as well as from strategic governmental projects. He is now involved in work on sustainable growth in cities.

Primary research interests are evolutionary ecology, behavior, sexual dimorphism, sexual selection and all aspects of conservation and sustainability. He has a special interest in using and developing advanced statistical and experimental methods. Jan has worked extensively with amphibian biology and restoration of ponds and wetlands, and is a keen herpetologist.

In 2004 he was awarded for outstanding teaching achievements by the student association at Örebro University (Sweden). Jan is also a popular science writer and photographer and have contributions published regularly.

Journal articles

D H Gustafson, A S L Andersen, G Mikusiński, J C Malmgren (2009)  Pond quality determinants for occurrence patterns of Great Crested Newts (Triturus cristatus).   Journal of Herpetology 43: 300-310  
Abstract: We used principal component analysis and logistic regression to evaluate the effect of eleven pond water quality variables on the presence and absence of Great Crested Newts (Triturus cristatus) in a cluster of 29 ponds in south-central Sweden. Variables of importance for the patterns observed were comprised into four principal components. Using logistic regression analysis and Akaike´s Information Criteria (AIC) we found that the best model explaining the distribution of Great Crested Newts included three of the principal components. Temperature and nutrient levels (nitrogen and phosphorus) were important in distinguishing between ponds with and without Great Crested Newts, whereas other physical variables were less important. Ponds with newts had higher temperatures and nutrient levels than ponds where the species was absent. Our results also suggest that the Great Crested Newt selects ponds with low nutrient levels for breeding, while they may be present in ponds with higher nutrient levels. Although this study was performed in a single area with a limited sample the results raise several issues of general importance for the management and conservation of Great Crested Newts in pond landscapes.
J C Malmgren, M Enghag (2008)  Female preference for male dorsal crests in great crested newts (Triturus cristatus)   Ethology Ecology & Evolution 20: 71-80  
Abstract: Studies of mate choice in great crested newts have established a difficulty in separating the visual constituent of the maleâs dorsal crest from its importance to cutaneous respiration and the conveying of pheromones during courtship. We used image manipulation to test if size differences in the dorsal crest alone can be evaluated visually by female newts, controlling for other differences between males. Females responded well to the experimental design and did not remain in front of simulated male âmodelsâ independently of differences in dorsal crest height. Instead, they spent more than twice as much time in front of the manipulated high-crested male, than in front of the non-manipulated low-crested male, which was significant also after controlling for zone area. However, the design failed to determine if females remained true to their first choice, probably due to a combination of low sample size and male âmodelsâ remaining unnaturally indifferent to female interest.
T Karlsson, P - E Betzholtz, J C Malmgren (2007)  Estimating viability and sensitivity of the great crested newt (Triturus cristatus) at a regional scale   Web Ecology 7: 63-76  
Abstract: <br><br> Viability and sensitivity of the great crested newt Triturus cristatus were simulated under different scenarios with a demographically and spatially structured stochastic model in an area of 144 km2 in southeastern Sweden. Eighteen ponds were monitored using drift fences with pitfall traps, funnel traps, visual observation and netting during the spring and summer of 2004. Estimated adult population sizes ranged between 0 and 620 individuals and the mean (±SD) local population size was 297±233 individuals. Due to uncertainty of the data, the model was simulated with parameter ranges to estimate upper and lower bounds of viability. Estimated quasi-extinction risk (the risk of each population in the study area falling below 10 females) within a 50-year period ranged from 100% to 0%, with a âbestâ estimate of 19.2%. The parameter most sensitive for the model outcome was fecundity, followed by juvenile survival, adult survival and transition from juvenile to adult. When these parameters were set at their lower bound, the quasi-extinction risk increased to 80â100%, while simulating these parameters at their higher bound inferred no or nearly no risk of quasi-extinction. This highlights the importance of focusing conservation efforts and research on the early life cycle stages. Management measures such as restoration of ponds and increased pond density decreased the risk for the great crested newt to end up quasi-extinct in the study area after 50 years. The results may have implications on management measures of great crested newts throughout its distribution area.
J C Malmgren, P-Å Andersson, S Ekdahl (2007)  Modelling terrestrial interactions and shelter use in great crested newts (Triturus cristatus)   Amphibia-Reptilia 28: 205-215  
Abstract: <br><br> The great crested newt (Triturus cristatus) is a pond-breeding salamander with a prolonged aquatic phase and a period of activity in the terrestrial environment prior to hibernation. Individuals use ground-covering objects and burrows as shelters from predators and unfavourable conditions. We investigated how interactions and spacing patterns were formed in staged experiments where paired newts were exposed to an arena with two shelters. Shelter use was predominant in all sets of great crested newts, irrespective of sex and size. Males and females differed in their shelter-use response. Females were more prone to reside in shelters when meeting other females than when meeting males, whereas males appeared indifferent to the sex of another individual. The social interaction was uniform for all combinations, with a 2:1 relation between the numbers of pairs sharing shelters vs. positioned in different shelters, instead of a random 1:1 distribution. Thus, the differences in shelter sharing could be attributed to the predominance of shelter use for females when meeting other females. We suggest that this behaviour, when females respond to the presence of another female, is a form of resource protection. Although sex effects were clearly noted, we could not demonstrate that size-related characteristics affected the outcome of any social interactions.
D H Gustafson, C Journath-Pettersson, J C Malmgren (2006)  Great crested newts (Triturus cristatus) as indicators of aquatic plant diversity   Herpetological Journal 16: 347-352  
Abstract: <br><br> In a field study in south central Sweden, we analysed the diversity of macrophytes in paired samples of ponds in a total of five geographically separated sites. Each pair of ponds involved one pond with presence of great crested newts (Triturus cristatus) and one pond in which newts were absent. Ponds with presence of great crested newts had a significantly higher mean number of plant species than ponds without newts. Newts occurred in ponds that tended to have a lower amount of pond area covered by surface vegetation, although this difference was not statistically significant. Macrophyte diversity also tended to increase more steeply in ponds with T. cristatus, compared with ponds without newts. Broad-leaved pond weed (Potamogeton natans) and square-leaved liverwort (Chiloscyphus pallescens) were among the plants that were most associated with presence of great crested newts. Plant diversity had a slightly more nested structure for ponds with great crested newts than for those without, which indicates a more homogeneous plant species assemblage in the former group of ponds. Overall, the results indicate that the great crested newt may be a reliable and useful indicator species for high plant species richness in ponds and small wetlands, which may be valuable for environmental monitoring and conservation in pond landscapes.
J C Malmgren (2002)  How does a newt find its way from a pond? Migration patterns after breeding and metamorphosis in great crested newts (Triturus cristatus) and smooth newts (T. vulgaris)   Herpetological Journal 12: 29-35  
Abstract: <br><br> Migration patterns across a drift fence with pitfall traps were studied between 1997 and 1999 at a breeding pond with populations of great crested newts, Triturus cristatus, and smooth newts, T. vulgaris, at a study site in south-central Sweden. Metamorphs and older newts emigrated from the pond non-randomly and seemed to avoid exiting where open fields adjoined, but were oriented towards a patch of forest immediately to the east of the pond. Movement patterns changed slightly over the years, but metamorphs were more dispersed and less concentrated than older newts, and did not choose directions identical to those of older newts. Older great crested and smooth newts showed similar directional orientation. Great crested newt metamorphs dispersed towards both edges of the forest patch, and possible explanations for this are discussed. The results suggest that orientation in relation to cues from the surroundings of a breeding pond may be used by newts to make migratory decisions.
J C Malmgren, M Thollesson (1999)  Sexual size and shape dimorphism in two species of newts, Triturus cristatus and T. vulgaris (Caudata: Salamandridae)   Journal of Zoology (Lond.) 249: 127-136  
Abstract: <br><br> Morphometric data from Fennoscandian populations of the crested newt Triturus cristatus and the smooth newt Triturus vulgaris were analysed for the presence of sexual size and shape dimorphism. The data sets included nine body-related and nine head-related measurements and were examined with univariate, bivariate and multivariate methods. Sexual dimorphism was demonstrated in both species. The separation of specimens was highly related to sex. Although the expression of sexual dimorphism differed between the two species, some patterns were shared. These are discussed in terms of evolution of intersexual dimorphism according to models of ecology, fecundity and sexual selection. In multivariate analyses, sexual dimorphism was restricted to body-related variables such as standard length and distance of extremities (with high values for females), contrasting against cloaca and limb-related characters (with high values for males). In both species, the `distance of extremities' measure (i.e. trunk length) was one of the strongest sexually dimorphic traits. No evidence of sexual dimorphism in head morphology was found. The results are interpreted as primarily concordant with theories on fecundity selection. For example, it has been suggested that females with larger trunk volumes increase their reproductive capacity. The fact that males had longer extremities, in relation to other characters measured, could be attributed to sexual selection. Long limbs in male newts may be bene®cial for courtship performance. Since head-related characters did not show any patterns of sexual dimorphism, no evidence was found to suggest that male and female crested and smooth newts have adapted to different feeding strategies.

Book chapters

P Angelstam, J Törnblom, E Degerman, L Henrikson, L Jougda, M Lazdinis, J C Malmgren, L Myhrman (2006)  From forest patches to functional habitat networks: the need for holistic understanding of ecological systems at the landscape scale   In: Farming, Forestry and the Natural Heritage: Towards a More Integrated Future 193-209 Edinburgh: Scottish Natural Heritage  
Abstract: <br><br>1. Maintaining biodiversity is a major challenge within the goal of sustainable development. <br><br> 2. In both terrestrial and aquatic environments, loss of biodiversity is usually related to long-term or intensive management reducing the number of species and natural habitat structures (e.g. dead wood). Management also affects important biotic processes such as browsing by deer through impacts on large carnivore populations, and abiotic processes such as altered fluvial dynamics within watersheds. Management of species, habitats and ecosystem functions are closely intertwined with each other, as well as with societyâs institutions. <br><br> 3. To assess the status of biodiversity, monitoring of state indicators over time should be combined with performance targets allowing assessment of the degree to which ecological sustainability has been achieved. Gap analysis and habitat models are two important tools for the strategic and tactical, respectively, assessment of the functionality of both terrestrial and aquatic habitat networks. However, unless the results of assessments can be communicated to different institutions and networks, appropriate management action may not take place. <br><br> 4. To improve the implementation of biodiversity policies on the ground, it is argued that natural and social sciences must be integrated in case studies with proactive bodies and businesses managing the social-ecological systems in which biodiversity is found. Ideally, whole landscapes or watersheds should be used as âlandscape laboratoriesâ for research, development and management.

Technical reports

J C Malmgren (2007)  Åtgärdsprogram för större vattensalamander och dess livsmiljöer (Triturus cristatus). [Species action plan for the great crested newt in Sweden.]   Stockholm: Naturvårdsverket [Swedish Environmental Protection Agency] Report No 5636.  
Abstract: <br><br>The great crested newt (Triturus cristatus) is a caudate amphibian with a complex life cycle that inhabits a large area of continental Europe, extending eastwards to the Ural mountain range. In Fennoscandia, the species occur in Denmark, Sweden, Norway and Finland, and Sweden has a responsibility for the predominant number of populations in Scandinavia. Even though the great crested newt is widespread geographically it is not particularly common, and it is still in decline with a rate that may locally be severe. Great crested newts are safeguarded by Swedish law. This provides strict protection of the species and its habitats, and a means by which sites can be protected from undesirable change. The species was listed as near threatened (category NT) in the Swedish red list, but was downgraded in the 2005 Swedish red list to category LC (least concern). However, a recent survey undertaken in 2005 revisited sites for great crested newts in four southcentral Swedish counties. The results demonstrate that the species could not be found in between 20-40 % (mean: 34 %) of the previously known sites. The study included all sites in the four counties that have the longest series of data from surveys of the species. The results (which will be published elsewhere) indicate that populations still and continuously suffer from loss of sites, mainly through habitat deterioration and natural succession due to lack of management, but also from filling and development. <br><br> Prime habitats for great crested newts in Scandinavia appear to be pond landscapes, or pondscapes (this term is adopted from conservation work on great crested newts in the UK), mainly in agricultural and cultural landscapes. This habitat is a mosaic composition of pasture and otherwise open grassland with small or large patches of predominantly deciduous forest, interpatched with wetlands and ponds. In some areas, and especially in the north, the species occur adjacent to conifer forest of pine and/or spruce, and breeds in small fish-free lakes and pools. Common to most terrestrial habitats are a wide variety of substrates for hiding and foraging, for example dead wood and rotting logs, rocks and boulders, and leaf litter. A prerequisite for successful reproduction, and for the long term stability of populations, is the presence of ponds without fish or crayfish. In natural pondscapes the mere availability of many different ponds buffer for coexistence of both fish and newts, but most modern pondscapes or relics thereof, have fewer alternative ponds left. Those that remain are often degraded in quality, and populations are therefore likely to be more sensitive to fish introduction. Although predatory fish and crayfish cause the most serious problems, even cyprinid fish have the potential to eliminate any reproductive success. Both current and historic loss of great crested newt populations in Sweden is mainly due to effects from water table reduction and infilling for farming and development. Ponds and small lakes have also been stocked with fish, or been exposed to waste disposal (including leakage of fertilizers and pesticides), resulting in deterioration of the habitats. Many ponds are also currently deteriorating through simple succession and overgrowth, due to lack of management and grazing. Furthermore, forest patches with dead wood have also been eliminated and the few patches remaining in the vicinity of ponds are therefore valuable for buffering further population loss. <br><br> Great crested newt conservation become more successful if a landscape approach to restoration and management of pond landscapes is adopted. The great crested newt may act as a flagship or symbol, species for biodiversity in pondscapes. Conservation efforts will also benefit other amphibians, many invertebrates â especially those with extended aquatic larval phases (e.g. dragon flies, water beetles), a broad variety of aquatic algae and plants (including stoneworts), as well as lichens, mosses and fungi. The habitat mosaic in pondscapes is also very beneficial for reptiles, birds and mammals. Great crested newts have many traits that make them vulnerable to alterations in their habitats. Among those is a genetic deficiency causing 50 % of all laid eggs to die before hatching (the Developmental Arrest Syndrome), which has severe effects on reproductive success. Anthropogenic disturbances may thus increase larval mortality beyond the threshold where all individuals fail to reproduce, and population stability is affected. However, individuals have a long life expectancy and high adult annual survival rate in stable terrestrial habitats (due to secretive habits and poisonous skin excretions), which may buffer for rapid local extinctions (discussed in Malmgren 2001). The most reliable information on the current distribution and status of the species in Sweden comes from the many surveys that have been conducted since around the mid-1980s. Over 4 000 ponds, poolsand small lakes have been surveyed and reported since 1990, and approximately 900 sites with great crested newts have been identified. Recent data indicate that only a minor percentage of these (around 1/3 any given year) may actually be functional for reproduction, and many may already have been lost, as mentioned above. <br><br> Conservation work for great crested newts and pond landscapes in Sweden is still in a rudimentary state. However, well established standardised methodologies adapted to Swedish conditions are available for both surveying and monitoring. Although the species has been the subject to several, but not all-inclusive surveys, landowners have generally not been informed about the results from surveys on their property. This may very well explain a significant amount of the habitat loss observed in the recent revisit survey. Nor have any directed conservation measures been taken to safeguard populations and sites at any larger scale. The exception is the southernmost county of Sweden, SkÃ¥ne, where massive efforts have been made to restore ponds for other amphibian species, which is likely to also have had a positive effect on the great crested newt. There have been several campaigns to support landowners, and especially farmers, to create ponds and wetlands, but not with the specific purpose to provide habitats for newts. Further, many landowners have introduced fish or crayfish in newly created ponds, and any effects for newts are therefore mainly negligible. <br><br> The Swedish action plan for the great crested newt is a guidance and is not legally binding. It aims at stabilizing the population decline and preventing habitat loss and habitat degradation in order to obtain favourable conservation status for the species in Sweden. The action plan includes information measures such as advice to landowners, inventories and monitoring, as well as efforts to manage, restore and create habitats in functional pond landscapes. The aim is also to identify and safeguard a number of larger areas of special concern for the species, where it has especially good survival prospects, and to initiate safeguarding of several smaller areas where pondscapes are still present. Prospects of stabilizing the decline of great crested newt populations are good, but coordination is essential in order for this action plan is to become successful. This requires a broad collaboration and exchange of information between governmental agencies, county administration boards, local communities, environmental and conservation organisations and volunteers. <br><br> The Swedish action plan for the great crested newt is valid during 2006-2010. Measures financed within the action plan are estimated to cost about 274 000 Euro. Further measures are financed through other governmental sources.
Notes: The report is written in Swedish, with English summary.
J C Malmgren, D H Gustafson, C Journath-Pettersson, U Grandin, H Rygne (2005)  Inventering och övervakning av större vattensalamander (Triturus cristatus). [Methods for surveying and monitoring the great crested newt.]   Stockholm: Naturvårdsverket [Swedish Environmental Protection Agency] Handbok i miljöövervakning [Handbook in Environmental Monitoring]  
Abstract: <br><br> This report is part of a series of methods for surveying and monitoring biodiversity in Sweden. It deals specifically with how to plan and proceed with surveys of the great crested newt in Scandinavian conditions. Further, it presents a plan for monitoring population status for the species using a landscape approach. It also deals with the statistics of evaluating monitoring data for the purpose of estimating status.
Notes: The report is written in Swedish, with no English summary.
J C Malmgren (2002)  Triturus cristatus Större vattensalamander [The great crested newt]   Uppsala: ArtDatabanken [Swedish Species Information Centre] Artfakta [Species fact sheet]  
Abstract: <br><br> The species fact sheet presents a review of the current status (at the time of publication) for the great crested newt in Sweden. It deals with basic biology and ecology, and with threats and problems. Furthermore, the report presents basic measures to protect the species in Sweden.
Notes: The report is written in Swedish, with no English summary.

PhD theses

J C Malmgren (2001)  Evolutionary Ecology of Newts   (PhD Thesis, Örebro Studies in Biology I) Örebro: Örebro University Press  
Abstract: <br><br> Sexual dimorphism, predator avoidance and migratory behaviour are adaptive traits that show variation at the population and species level. Such features respond to the environment in the broad sense, that is, when both abiotic and biotic components are included. Newts of the genus Triturus have several unique features and therefore make interesting model organisms. <br><br> I use multivariate methods to test predictions about the evolution of sex differences in morphological traits. There was no evidence for dimorphism due to diverging feeding niche specialisation between the sexes in great crested and smooth newts (Triturus cristatus and T. vulgaris, respectively). The sexes, on the other hand, diverged in traits related to female fecundity and male reproductive success. Within the genus Triturus, there was no overall allometry for sexual size dimorphism (SSD), but subgenus Triturus, a lineage comprised by medium- to large-bodied species, were significantly allometric, and SSD decreased with increasing body size for male-biased taxa and increased with size for female-biased taxa. Species in the marmoratus-cristatus species group were almost perfectly isometric, but female-biased. With respect to an ancestral state, I suggest that differences in mating system have caused medium- and small-bodied species (subgenus Palaeotriton) to decrease SSD with smaller body size, whereas subgenus Triturus have evolved larger body size with a reversal from male- to female-biased SSD. Several peculiar traits are common to the latter group. I argue, and present a conceptual model, that the reversal is an adaptation to genetic constraints posed by a balanced lethal system (the developmental arrest syndrome). Several life history traits, as well as morphological and reproductive traits, may be interpreted as evidence for the scenario. Predictions from the model are presented and future research to test the validity of the model is encouraged. <br><br> Newts are threatened by the introduction of fish and predictions from a predator-prey model on the evolution of predator avoidance behaviour, are tested. The results suggest that the great crested newt may be able to detect chemical cues from the ninespined stickleback, Pungitius pungitius, and adjust its behaviour accordingly. The response could be a predator avoidance response that enables adults to increase reproductive success by eliminating predation risk. I also studied migration behaviour in response to surrounding landscape elements after breeding and metamorphosis in great crested and smooth newts. Fragmentation effects reduce the chance for newts to disperse to suitable habitat patches in the landscape. I demonstrate that newts appear to orientate towards forest non-randomly, regardless of age-class or species, and their responses may be used to predict where critical elements for population persistence are located, in relation to a breeding pond. Overall, the results from my studies suggest that the great crested newt may be more prone to local extinction than previously believed, much due to genetic constraints and possible habitat specialisation. I use the results to present avenues for future research and discuss implications from my studies for management and conservation of newts and newt-friendly landscapes. <br><br> Dissertation thesis for PhD degree in Biology, authored by Dr Jan C Malmgren. The thesis was defended and approved at the Department of Natural Sciences, Ãrebro University, Sweden, November 30 2001. Opponent on the thesis was Dr Hanna Kokko. The thesis is written in English, includes a summarized section and five papers, of which two has been published elsewhere. <br><br> Please note that the pdf is 16 MB.
Notes: <br><br> Errata list <br><br> Corrections to appended papers I-V; <br><br> Paper II, p. 6. Supplement to caption of Figure 3; <br> Solid lines represent major axis regression models for (a) the entire genus Triturus, (b) the subgenus Palaeotriton, and (c) subgenus Triturus. <br><br> Paper III, p. 2. Supplement to Figure 1 (reference letters in figure have been lost); <br> Close to the root of subgenus Palaeotriton, write a. Close to the root of subgenus Triturus, write b. Between the branching roots of vittatus and marmoratus, write c. At the branching roots of the four species in the âcrested newt superspeciesâ, write d. <br><br> Paper III, p. 12. Error on line 1; <br> â⦠and change from 13â14 ( â¦â, replace with â⦠and change from 13 to 14 ( â¦â <br><br> Paper III, p. 13. Supplement to caption of Figure 4; <br> Filled circles represent species within subgenus Palaeotriton, whereas empty circles represent species within subgenus Triturus.

Popular science

J C Malmgren (2008)  Tyst myller i Smoky Mountains [Silent diversity in Smoky Mountains]   Fauna och flora 103(3): 2-7 [Popular science]  
Abstract: The Smoky Mountains National Park is a biodiversity hotspot in general, but for salamandrids in particular. This popular science article is a short note, richly illustrated with colour photos, presenting some of its key inhabitants - the lungless salamanders.
Notes: In Swedish, with 6 figs.
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