Final Report Summary - CLIMADAPT (Testing the limits and potential of evolution in response to climate change)
Predicting how quickly ongoing environmental change will cause population extinction is a critical scientific issue at a time when human activity is changing habitats in time and space at unprecedented rates. Crucially, we lack an understanding of how quickly the ecological tolerance of a population can change as a result of evolutionary change. In order to understand such limits to adaptation, it is essential to uncover the genetic basis of key phenotypes and to consider how ecological factors, in particular species interactions, determine variation in fitness and drive evolutionary change in natural populations.
By linking genome-wide genetic variation with ecological assays we investigated evolutionary responses to climate change in the Brown Argus butterfly, a species that has recently undergone rapid range expansion in the UK. This species is one of few specialists that has adapted to climate change by shifting its use of host plant species. This makes it an important study system to investigate the nature of genetic variation underpinning ecologically important traits in the field (in particular host preference and fecundity), the role such variation plays in shaping adaptive population divergence across species’ ranges, and the demographic history of rapid range expansions that occur in response to recent climate change.
During the summers of 2013 and 2014 Dr de Jong, with the help of several student field assistants, assayed the host plant preference and fecundity of individual females in large outdoor common garden experiments. This allowed measurement of genetic variation in these crucial biotic interactions within and among nine populations from the established and new parts of the Brown Argus range. These results show a significant shift in host plant preference between the established and new populations. They also indicate for the first time that individual females differ in their host preferences, in that females collected from a single population may be either be restricted to a single host plant, or be able to use both host plants. Furthermore, our data reveal significantly reduced levels of such within-population variation for preference in newly established populations. This evolutionary shift, and the associated reduction of variation in preference is in turn likely to limit future evolution in the range margin populations. The phenotypic data on female host plant preference under common garden conditions also provides a unique dataset with which to test for phenotype-genotype associations using genome-wide sequence variation.
We obtained additional funding and bioinformatics support from the Biomolecular Analysis Facility (NBAF) of the UK’s Natural Environment Research Council (NERC) to increase the power of the next-generation sequencing component of this project. This enabled us to individually sequence a large number of butterflies for each of nine populations, for high-density genome-wide genetic loci (RADseq). We used this data in three main ways: 1) to investigate the genetic basis of host plant preference and fecundity; 2) to test for adaptive differentiation in these traits in association with the range expansion, and 3) to reconstruct the colonisation history and on-going migration during range expansion. Preliminary analysis of these data indicate that the range expansion occurred via a spread from isolated populations from the eastern part of the UK range, rather than colonisation from the more dense southern populations.
This project was very successful in generating a very large amount of unique data on genetic variation in ecologically relevant traits under controlled field conditions, as well as the first to generate high-density genomic data for the Brown Argus butterfly, an organism which has already been the focus of detailed ecological research. The integration of the large phenotypic and genetic datasets generated by this project is essential to test theoretical models of adaptation, and to make useful predictions of how species and ecological communities are likely to respond to anthropogenic environmental change through evolutionary responses in their biotic interactions. Analysis of these data is continuing in collaboration with Prof Mark Beaumont (University of Bristol), and Prof Chris Jiggins (University of Cambridge). The results of these analyses will allow us to provide important scientific guidance regarding the chance of extinction due to climate change of specialist organisms, the likelihood that such adaptive changes can persist in the longer term, and whether translocation of individuals between southern and northern populations (as is often advocated by conservation groups) would increase the adaptive potential of organisms that depend on specific species interactions for their persistence.
By linking genome-wide genetic variation with ecological assays we investigated evolutionary responses to climate change in the Brown Argus butterfly, a species that has recently undergone rapid range expansion in the UK. This species is one of few specialists that has adapted to climate change by shifting its use of host plant species. This makes it an important study system to investigate the nature of genetic variation underpinning ecologically important traits in the field (in particular host preference and fecundity), the role such variation plays in shaping adaptive population divergence across species’ ranges, and the demographic history of rapid range expansions that occur in response to recent climate change.
During the summers of 2013 and 2014 Dr de Jong, with the help of several student field assistants, assayed the host plant preference and fecundity of individual females in large outdoor common garden experiments. This allowed measurement of genetic variation in these crucial biotic interactions within and among nine populations from the established and new parts of the Brown Argus range. These results show a significant shift in host plant preference between the established and new populations. They also indicate for the first time that individual females differ in their host preferences, in that females collected from a single population may be either be restricted to a single host plant, or be able to use both host plants. Furthermore, our data reveal significantly reduced levels of such within-population variation for preference in newly established populations. This evolutionary shift, and the associated reduction of variation in preference is in turn likely to limit future evolution in the range margin populations. The phenotypic data on female host plant preference under common garden conditions also provides a unique dataset with which to test for phenotype-genotype associations using genome-wide sequence variation.
We obtained additional funding and bioinformatics support from the Biomolecular Analysis Facility (NBAF) of the UK’s Natural Environment Research Council (NERC) to increase the power of the next-generation sequencing component of this project. This enabled us to individually sequence a large number of butterflies for each of nine populations, for high-density genome-wide genetic loci (RADseq). We used this data in three main ways: 1) to investigate the genetic basis of host plant preference and fecundity; 2) to test for adaptive differentiation in these traits in association with the range expansion, and 3) to reconstruct the colonisation history and on-going migration during range expansion. Preliminary analysis of these data indicate that the range expansion occurred via a spread from isolated populations from the eastern part of the UK range, rather than colonisation from the more dense southern populations.
This project was very successful in generating a very large amount of unique data on genetic variation in ecologically relevant traits under controlled field conditions, as well as the first to generate high-density genomic data for the Brown Argus butterfly, an organism which has already been the focus of detailed ecological research. The integration of the large phenotypic and genetic datasets generated by this project is essential to test theoretical models of adaptation, and to make useful predictions of how species and ecological communities are likely to respond to anthropogenic environmental change through evolutionary responses in their biotic interactions. Analysis of these data is continuing in collaboration with Prof Mark Beaumont (University of Bristol), and Prof Chris Jiggins (University of Cambridge). The results of these analyses will allow us to provide important scientific guidance regarding the chance of extinction due to climate change of specialist organisms, the likelihood that such adaptive changes can persist in the longer term, and whether translocation of individuals between southern and northern populations (as is often advocated by conservation groups) would increase the adaptive potential of organisms that depend on specific species interactions for their persistence.