Presentation and Research Interests
My name is Mathieu Chouteau, I'm a Canadian researcher, currently part of the Ecology and Evolution of the Amazonian Biodiversity research team in Cayenne.
My research aims to better understand and predict the evolutionary trajectory of population differentiation and adaptation so as to implement better management practices. To do so, I use a comparative approach over various study systems and combine the identification of genes and mutations underlying individual variability with the ecological, evolutionary and demographic mechanisms that determine their respective benefits within natural systems. My approach enables to fill the gap between the identification of relevant genetic variants and the ecological mechanisms explaining their success in natural populations.
My name is Mathieu Chouteau, I'm a Canadian researcher, currently part of the Ecology and Evolution of the Amazonian Biodiversity research team in Cayenne.
My research aims to better understand and predict the evolutionary trajectory of population differentiation and adaptation so as to implement better management practices. To do so, I use a comparative approach over various study systems and combine the identification of genes and mutations underlying individual variability with the ecological, evolutionary and demographic mechanisms that determine their respective benefits within natural systems. My approach enables to fill the gap between the identification of relevant genetic variants and the ecological mechanisms explaining their success in natural populations.
Ongoing Projects
.Understanding the adaptive consequences associated with genome reorganisation
The identification of supergenes and chromosome inversions has become a hot topic in evolutionary biology. These genome rearrangements are hypothesized to capture gene combinations favoured under certain environmental conditions, and by suppressing recombination, are thought to facilitate the segregation of co-adapted allelic variations. Although those major loci are commonly assumed to be shaped by natural selection, little is known about the fitness components, and their interaction, involved with these types of structural reorganisation. In this context, my work on mimetic butterflies strongly suggests that these genome reorganisations, by disturbing recombination (i.e. difficulty to purge captured deleterious mutations), can have strong, long term fitness costs. The existence of such consequences, whereas locally favourable co-adapted alleles become linked to recessive lethals, has drawn little attention so far, even though this phenomenon appears to be widespread and could potentially explain numerous “puzzling” cases of sympatric adaptive polymorphism. I am currently pursuing this research avenue, using the relevance of the mimicry supergene of the Neotropical butterfly Heliconius numata, so as to determine how these genomic rearrangements can sometime generate antagonistic selection pressures that shape adaptive diversity.
The identification of supergenes and chromosome inversions has become a hot topic in evolutionary biology. These genome rearrangements are hypothesized to capture gene combinations favoured under certain environmental conditions, and by suppressing recombination, are thought to facilitate the segregation of co-adapted allelic variations. Although those major loci are commonly assumed to be shaped by natural selection, little is known about the fitness components, and their interaction, involved with these types of structural reorganisation. In this context, my work on mimetic butterflies strongly suggests that these genome reorganisations, by disturbing recombination (i.e. difficulty to purge captured deleterious mutations), can have strong, long term fitness costs. The existence of such consequences, whereas locally favourable co-adapted alleles become linked to recessive lethals, has drawn little attention so far, even though this phenomenon appears to be widespread and could potentially explain numerous “puzzling” cases of sympatric adaptive polymorphism. I am currently pursuing this research avenue, using the relevance of the mimicry supergene of the Neotropical butterfly Heliconius numata, so as to determine how these genomic rearrangements can sometime generate antagonistic selection pressures that shape adaptive diversity.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655857
Linking the ecology and genetics of Amazonian diversification: the Peruvian poison dart frogs of the genus Ranitomeya.
The poison dart frogs of the genus Ranitomeya display a rich polymorphism of warning color patterns which can easily rival the diversity of ecomorphs sometimes found between isolated islands (e.g. finches, anoles, strawberry dart frogs). However, in the case of these frogs, there are no strict geographic barriers to migration explaining the maintenance of this adaptive diversity within species. In these situations, the persistence of strikingly different complex adaptive phenotypes relies strongly on the establishment of barriers to genetic recombination so that co-adapted alleles can remain together. The uniqueness of the Ranitomeya system is that because each species displays a different level of geographic polymorphism, this system provides a rare opportunity for the comparative investigation of the impact of these barriers on the processes of local adaptation. Three main themes are under investigation
The poison dart frogs of the genus Ranitomeya display a rich polymorphism of warning color patterns which can easily rival the diversity of ecomorphs sometimes found between isolated islands (e.g. finches, anoles, strawberry dart frogs). However, in the case of these frogs, there are no strict geographic barriers to migration explaining the maintenance of this adaptive diversity within species. In these situations, the persistence of strikingly different complex adaptive phenotypes relies strongly on the establishment of barriers to genetic recombination so that co-adapted alleles can remain together. The uniqueness of the Ranitomeya system is that because each species displays a different level of geographic polymorphism, this system provides a rare opportunity for the comparative investigation of the impact of these barriers on the processes of local adaptation. Three main themes are under investigation
- Genomic - Identifying the loci underlying the diversity of warning coloration
- Evolutionary Ecology – Assessing how geographic polymorphism in maintained
- Conservation – applying genomics to biodiversity preservation
Visual summary of the association mapping crosses for R. fantastica (blue boxes), R. imitator (green boxes) and R. variabilis (orange box). Pictured are a selection of the actual individuals for each generations. These crosses are essential to dissect the genetic architecture behind color-pattern variations.
Unpalatability and the organization of mimetic community assemblage
|
Dissection of a mimicry supergene
In collaboration with Dr Suzanne Saenko & Dr Violaine Llaurens
In the butterfly Heliconius numata, the wing color patterns resemble that of other local unpalatable species, and thus acts as a warning signal of toxicity for predators. These complex wing color patterns are mainly controlled by a single locus, the P supergene, which contains about 18 genes. The hierarchical relationship of dominance among the haplotypes at the supergene P is predicted to be under high selective constraints due to the increased predation risk of non-mimetic heterozygotes. Using varied approaches, we aim to 1) quantify the variation in dominance among wing color haplotypes in natural populations and investigate the role of the genetic background, 2) characterize the molecular basis of dominance, and finally, 3) assess the selective advantage of dominance.
In collaboration with Dr Suzanne Saenko & Dr Violaine Llaurens
In the butterfly Heliconius numata, the wing color patterns resemble that of other local unpalatable species, and thus acts as a warning signal of toxicity for predators. These complex wing color patterns are mainly controlled by a single locus, the P supergene, which contains about 18 genes. The hierarchical relationship of dominance among the haplotypes at the supergene P is predicted to be under high selective constraints due to the increased predation risk of non-mimetic heterozygotes. Using varied approaches, we aim to 1) quantify the variation in dominance among wing color haplotypes in natural populations and investigate the role of the genetic background, 2) characterize the molecular basis of dominance, and finally, 3) assess the selective advantage of dominance.
Completed projects
Understanding the processes driving and maintaining adaptive divergence
Aposematic signals are some of the most well understood examples of how natural selection can maintain stable phenotypes. Individuals that deviate from the predators’ recognized signal will suffer increased predation, thus preventing any possibility of warning signal diversification. Yet impressive variations in warning signals are observed among populations of many different species, often times at relatively small spatial scales. During my PhD, I investigated this puzzling challenge using the poison-dart frog Ranitomeya imitator as a study model. This involved a combination of molecular tools (e.g. microsatellites, Mitochondrial D-loop), population genetic analyses (e.g. genetic admixture, assignment test, gene flow, genetic differentiation), population phenotypic data (e.g. developing color-pattern quantification analysis), and the use of artificial mock-up models to quantify predation rates in the natural habitats.
This research resulted in several contributions to the field of evolutionary biology such as: 1) providing the first case of empirical evidence for Wright’s Shifting Balance theory in a natural system, in addition to demonstrating how it may promote adaptive diversification. This textbook evolutionary theory has long been criticized for its lack of evidence in natural systems. 2) Demonstrating how the interactions between an organism’s warning signals and the predator community can lead to the maintenance of a stable geographic mosaic of aposematic adaptation. The existence of such geographic mosaics, which contradicts current theoretical work, has long puzzled the research community. And finally, 3) rekindling the debate between the hypotheses of phenotypic advergence vs. convergence in Müllerian mimetic relationships (i.e., one species evolving towards the phenotype of another species vs. two species both evolving towards a middle ground phenotype).
Aposematic signals are some of the most well understood examples of how natural selection can maintain stable phenotypes. Individuals that deviate from the predators’ recognized signal will suffer increased predation, thus preventing any possibility of warning signal diversification. Yet impressive variations in warning signals are observed among populations of many different species, often times at relatively small spatial scales. During my PhD, I investigated this puzzling challenge using the poison-dart frog Ranitomeya imitator as a study model. This involved a combination of molecular tools (e.g. microsatellites, Mitochondrial D-loop), population genetic analyses (e.g. genetic admixture, assignment test, gene flow, genetic differentiation), population phenotypic data (e.g. developing color-pattern quantification analysis), and the use of artificial mock-up models to quantify predation rates in the natural habitats.
This research resulted in several contributions to the field of evolutionary biology such as: 1) providing the first case of empirical evidence for Wright’s Shifting Balance theory in a natural system, in addition to demonstrating how it may promote adaptive diversification. This textbook evolutionary theory has long been criticized for its lack of evidence in natural systems. 2) Demonstrating how the interactions between an organism’s warning signals and the predator community can lead to the maintenance of a stable geographic mosaic of aposematic adaptation. The existence of such geographic mosaics, which contradicts current theoretical work, has long puzzled the research community. And finally, 3) rekindling the debate between the hypotheses of phenotypic advergence vs. convergence in Müllerian mimetic relationships (i.e., one species evolving towards the phenotype of another species vs. two species both evolving towards a middle ground phenotype).
This project has received funding from the Natural Sciences and Engineering Research Council of Canada.
Aposematic polymorphism under antagonistic selection
|
Adaptive resource allocation in plants
During my graduate work, I also investigated adaptive strategies of gamete allocation (i.e. Pollen/Ovule) in plants. This research has highlighted, for the Aroids family, that resource allocation of gametes is highly influenced by the efficiency of pollinators, the duration and harshness of the growing season, and, quite unexpectedly, was not related to the mating system. This new insight into specialized floral structure in relation to the pollinator type furthers our understanding and our ability to identify pollination syndromes.
This project has received funding from the Natural Sciences and Engineering Research Council of Canada.
During my graduate work, I also investigated adaptive strategies of gamete allocation (i.e. Pollen/Ovule) in plants. This research has highlighted, for the Aroids family, that resource allocation of gametes is highly influenced by the efficiency of pollinators, the duration and harshness of the growing season, and, quite unexpectedly, was not related to the mating system. This new insight into specialized floral structure in relation to the pollinator type furthers our understanding and our ability to identify pollination syndromes.
This project has received funding from the Natural Sciences and Engineering Research Council of Canada.