Uppsala University
Dept of Ecology and Evolution
Population Biology and Conservation Biology
Norbyvägen 18 D
SE-752 36 Uppsala
Sweden
 | arichterboix@ub.edu alex.richter@ebc.uu.se |
I study ecology and evolution of amphibian communities in mediterranean freshwater aquatic systems. To date I have worked on larval anurans. I am particularly interested in how animals resolve the trade-offs they are faced with and the role of phenotypic plasticity and population structure. I consider this at both ecological and evolutionary scales, combining field studies with laboratory experiments. To address this general problem, I measure traits important to the animal's performance (and ultimately, fitness) in its habitat and consider these trait values in the context of present-day habitat type and evolutionary history.
I developed my thesis research at the University of Barcelona (Spain) with Dr. Gustavo Llorente as tutor. The thesis research concerned evolutionary ecology and community ecology of amphibians in two different areas of a Mediterranean region. The goal of the research was to test how anuran species coexist along a lentic freshwater gradient from ephemeral to permanent ponds. The community structure across the gradient has been explained by different ecological models, based on different trade-offs and inherent properties of the species. To test the different models he used four-year field surveys of communities to characterise pond-breeding habitats (with respect to temporariness, predator abundance and competitor abundance) and to evaluate the dynamics and spatial structures of the metacommunity. He also designed lab experiments to quantify species traits and phenotypic plasticity (life-history, morphological and behavioural traits) in response to different circumstances found in nature: pond drying, presence of invertebrate predators and intra- and interspecific competition. Comparative analysis of phenotypic plasticity traits was made in relation to species ecological breadths (quantified from field surveys) and phylogenetic relationships. In general, species that use a wide variety of habitats or unpredictable environments showed a greater plasticity of responses than those occurring in predictable habitats. At the two extremes of the hydroperiod (ephemeral and permanent ponds) there were specialists with limited plasticity, whereas species from intermediate temporary ponds showed higher levels of plasticity. Results therefore supported the hypothesis that interspecific differences in plasticity are adaptive and are related to ecological breadth and unpredictability of habitat. The correlations among traits of the different species reflected trade-offs suggested by the models (colonisation-competition; predator-permanence gradient; and competition ability-permanence gradient), but correlation coefficients did not favour any single trade-off model over the others. These results suggest that the community studied can be interpreted as a metacommunity in which local interactions and regional processes (colonisation-extinction rates) are related, and they emphasise the importance of habitat heterogeneity for both: local and regional diversity maintenance.
*** Research interest
for more information visit: http://web.me.com/alexrichterboix/Homepage/Welcome.html
One of the great challenges for the 21st century is to develop and implement strategies to avoid loosing a large amount of biodiversity. This becomes crucial by taking into account the high current rates of human population growth and energy use, the increasing demand for area and, consequently, the high rates of habitat loss, fragmentation and species extinctions. Contemporary populations are increasingly threatened by these human-induced environmental changes, because modify habitats and often cause strong selection at very short time-scales. In the past few decades, studies by evolutionary biologists have revealed that selection in natural populations can be strong, and can cause evolutionary shifts within a few generations. The majority of rapid evolutionary changes reported in natural populations involve response to anthropogenic pressures, but many local populations fail to adapt to such changes and suffer extinctions. The recognition of these fast evolutionary processes within a few generations has stimulated an awareness that evolutionary concepts need to be incorporated in conservation thinking, which can have important consequences for species conservation, management and restoration.
Genetic variation provides the heritable resource that serves as the basis for evolutionary change, and loss of genetic diversity may, over time, negatively impact a population’s viability and the potential for further adaptive change in response to new selective challenges. However, most conservation geneticists only use molecular marker traits, and many discussions of genetics in conservation biology have centered on the topic of heterozygosity or related measures of the within-population component of genetic variation, yet these may not reflect the adaptive potential of populations. Causal links between genetic variation in populations and fitness have proved difficult to establish, and molecular markers usually do not reflect patterns of selection. As a result, neutral molecular markers cannot be used to infer scales of adaptation or patterns of variation in traits that might be important in adapting to a changing environment. Therefore other populations traits more clearly related to fitness must be measured to estimate diversity and develop management programs to preserve ecotypes and evolutionary mechanisms. Quantitative genetic techniques have not yet received much attention in the conservation field, but are likely to reveal the variation that is most closely associated with components of fitness. Measures of quantitative genetic variation do better reflect variation in fitness traits, but the distribution of quantitative genetic variation in natural environments is poorly understood, especially in species that live in metapopulations.
In this context, it is now recognized that knowledge of population genetic structure and genetic diversity distribution are important to evaluate population viability and establish significant units for conservation. Perhaps more importantly, patterns of genetic structure within and among populations should be integrated into a more complex evaluation of human occupation patterns, so that genetic parameters can be explicitly analyzed on a human occupied landscape. This also leads to an evaluation of how human modifications at landscape level affect genetic diversity. Both possibilities can be integrated into a single framework, which has been recently called “landscape genetics”, analogous to the well-established field of landscape ecology, but for the moment this integration only incorporates molecular genetic data with landscape information without including quantitative genetic data of phenotypic fitness related traits. Population, quantitative and landscape genetics have developed rapidly in recent years but there is a need now to integrate these fields for practical applications in ecology and conservation biology.
Amphibians have been widely used as indicators of habitat change, because they are quite sensitive to human induced habitat changes. At the same time, there is a general need to understand these effects, because amphibian population declines have been reported worldwide. Studies in amphibian population genetics revealing a high level of population structure, which can be associated with their ecological and behavioral characteristics, especially the relatively low dispersion rates, high habitat fidelity and specificity. The effects of habitat loss and fragmentation cannot be understood at local spatial scales, and analyses at broader geographical extents (at least regional or landscape levels) are necessary to evaluate how complex processes related to human occupation interact at these scales and affect biodiversity.
Many studies in conservation genetics have been focused on endangered species, hoping that a better understanding of genetic parameters furnishes effective information to increase their persistence. On the other hand, species locally abundant or widely distributed can be informative on how broad scale processes of habitat loss and fragmentation affected population genetic structure. These approaches are of course not mutually exclusive, but this partition may be useful to ensure how non-endangered, highly abundant and widely distributed species are also important targets for applied genetic analyses. We will investigate how landscape structure affects the distribution of quantitative and molecular genetic variation of the widely distributed frog Rana arvalis in Uppland (Sweden). To do that we will combine molecular genetics analyses with quantitative genetic experiments and landscape studies to increase our understanding of genetic diversity distribution.
I developed my thesis research at the University of Barcelona (Spain) with Dr. Gustavo Llorente as tutor. The thesis research concerned evolutionary ecology and community ecology of amphibians in two different areas of a Mediterranean region. The goal of the research was to test how anuran species coexist along a lentic freshwater gradient from ephemeral to permanent ponds. The community structure across the gradient has been explained by different ecological models, based on different trade-offs and inherent properties of the species. To test the different models he used four-year field surveys of communities to characterise pond-breeding habitats (with respect to temporariness, predator abundance and competitor abundance) and to evaluate the dynamics and spatial structures of the metacommunity. He also designed lab experiments to quantify species traits and phenotypic plasticity (life-history, morphological and behavioural traits) in response to different circumstances found in nature: pond drying, presence of invertebrate predators and intra- and interspecific competition. Comparative analysis of phenotypic plasticity traits was made in relation to species ecological breadths (quantified from field surveys) and phylogenetic relationships. In general, species that use a wide variety of habitats or unpredictable environments showed a greater plasticity of responses than those occurring in predictable habitats. At the two extremes of the hydroperiod (ephemeral and permanent ponds) there were specialists with limited plasticity, whereas species from intermediate temporary ponds showed higher levels of plasticity. Results therefore supported the hypothesis that interspecific differences in plasticity are adaptive and are related to ecological breadth and unpredictability of habitat. The correlations among traits of the different species reflected trade-offs suggested by the models (colonisation-competition; predator-permanence gradient; and competition ability-permanence gradient), but correlation coefficients did not favour any single trade-off model over the others. These results suggest that the community studied can be interpreted as a metacommunity in which local interactions and regional processes (colonisation-extinction rates) are related, and they emphasise the importance of habitat heterogeneity for both: local and regional diversity maintenance.
*** Research interest
for more information visit: http://web.me.com/alexrichterboix/Homepage/Welcome.html
One of the great challenges for the 21st century is to develop and implement strategies to avoid loosing a large amount of biodiversity. This becomes crucial by taking into account the high current rates of human population growth and energy use, the increasing demand for area and, consequently, the high rates of habitat loss, fragmentation and species extinctions. Contemporary populations are increasingly threatened by these human-induced environmental changes, because modify habitats and often cause strong selection at very short time-scales. In the past few decades, studies by evolutionary biologists have revealed that selection in natural populations can be strong, and can cause evolutionary shifts within a few generations. The majority of rapid evolutionary changes reported in natural populations involve response to anthropogenic pressures, but many local populations fail to adapt to such changes and suffer extinctions. The recognition of these fast evolutionary processes within a few generations has stimulated an awareness that evolutionary concepts need to be incorporated in conservation thinking, which can have important consequences for species conservation, management and restoration.
Genetic variation provides the heritable resource that serves as the basis for evolutionary change, and loss of genetic diversity may, over time, negatively impact a population’s viability and the potential for further adaptive change in response to new selective challenges. However, most conservation geneticists only use molecular marker traits, and many discussions of genetics in conservation biology have centered on the topic of heterozygosity or related measures of the within-population component of genetic variation, yet these may not reflect the adaptive potential of populations. Causal links between genetic variation in populations and fitness have proved difficult to establish, and molecular markers usually do not reflect patterns of selection. As a result, neutral molecular markers cannot be used to infer scales of adaptation or patterns of variation in traits that might be important in adapting to a changing environment. Therefore other populations traits more clearly related to fitness must be measured to estimate diversity and develop management programs to preserve ecotypes and evolutionary mechanisms. Quantitative genetic techniques have not yet received much attention in the conservation field, but are likely to reveal the variation that is most closely associated with components of fitness. Measures of quantitative genetic variation do better reflect variation in fitness traits, but the distribution of quantitative genetic variation in natural environments is poorly understood, especially in species that live in metapopulations.
In this context, it is now recognized that knowledge of population genetic structure and genetic diversity distribution are important to evaluate population viability and establish significant units for conservation. Perhaps more importantly, patterns of genetic structure within and among populations should be integrated into a more complex evaluation of human occupation patterns, so that genetic parameters can be explicitly analyzed on a human occupied landscape. This also leads to an evaluation of how human modifications at landscape level affect genetic diversity. Both possibilities can be integrated into a single framework, which has been recently called “landscape genetics”, analogous to the well-established field of landscape ecology, but for the moment this integration only incorporates molecular genetic data with landscape information without including quantitative genetic data of phenotypic fitness related traits. Population, quantitative and landscape genetics have developed rapidly in recent years but there is a need now to integrate these fields for practical applications in ecology and conservation biology.
Amphibians have been widely used as indicators of habitat change, because they are quite sensitive to human induced habitat changes. At the same time, there is a general need to understand these effects, because amphibian population declines have been reported worldwide. Studies in amphibian population genetics revealing a high level of population structure, which can be associated with their ecological and behavioral characteristics, especially the relatively low dispersion rates, high habitat fidelity and specificity. The effects of habitat loss and fragmentation cannot be understood at local spatial scales, and analyses at broader geographical extents (at least regional or landscape levels) are necessary to evaluate how complex processes related to human occupation interact at these scales and affect biodiversity.
Many studies in conservation genetics have been focused on endangered species, hoping that a better understanding of genetic parameters furnishes effective information to increase their persistence. On the other hand, species locally abundant or widely distributed can be informative on how broad scale processes of habitat loss and fragmentation affected population genetic structure. These approaches are of course not mutually exclusive, but this partition may be useful to ensure how non-endangered, highly abundant and widely distributed species are also important targets for applied genetic analyses. We will investigate how landscape structure affects the distribution of quantitative and molecular genetic variation of the widely distributed frog Rana arvalis in Uppland (Sweden). To do that we will combine molecular genetics analyses with quantitative genetic experiments and landscape studies to increase our understanding of genetic diversity distribution.
