Jurgen Otto CC-BY-SA 2.0, and Eva van der Heijden, Wellcome Sanger Institute

Meier Group

Genomics of evolution and rapid speciation

Biodiversity is very unevenly distributed across the tree of life. While the evolution of new species typically takes millions of years, some groups of organisms adapt and diversify much faster, with new species evolving in just thousands of years. Using whole genome sequencing of hundreds of butterflies, spiders, and other animals and plants, we compare lineages with slow and fast diversification rates to assess genomic and other factors that facilitate rapid evolution.

Our work

We are evolutionary biologists using genomics to study the rapid emergence of new species, i.e. speciation, and adaptation. We work on different groups of animals and plants that show large variation in the speed of speciation. We compare fast and slowly speciating lineages within those groups to assess the factors that contribute to rapid speciation. We are particularly interested in the roles of chromosomal rearrangements, the genetic basis of relevant traits and the effects of interbreeding.

Genomic data has revealed that interbreeding is much more widespread in nature than anticipated. Interbreeding can lead to the fusion of species and thus biodiversity loss. However, recent work, including ours, shows that sometimes interbreeding can lead to exchange of genetic variants between species that can speed up adaptation and speciation. Interbreeding can generate populations of mixed ancestry with novel combinations of gene variants that can evolve into new species. Usually adaptation is very slow, as the waiting time for beneficial mutations is long. However, interbreeding can speed up the process as adaptive gene variants can be exchanged between species. Sequencing genomes allows us to identify instances of interbreeding at different points throughout the evolutionary history of species. We can trace back the origin of genetic variants and thus understand the impact of interbreeding on biodiversity.

Genomic data analysis also allows us to identify genes that contribute to speciation and adaptation. We can then study how these genes are arranged on the chromosomes. Some of the species we study show vast variation in chromosomal numbers and we investigate how chromosomal fusions, fissions and rearrangements contributed to their rapid diversification. Such chromosomal rearrangements can contribute to speciation because populations with different chromosomes may not be able to interbreed successfully, or because rearrangements may link together co-adapted genes.

We work collaboratively with research partners around the globe, studying a diverse range of animals and plants across the tree of life. Our aim is to find the universal underlying genomic mechanisms of rapid evolution; so we are open to collaborations that will enable us to apply large-scale sequencing and analysis to any groups that best represent different forms of fast evolution in action.

Two of the key taxonomic groups that we study represent quite different forms of evolution. Ithomiini butterflies form adaptive radiations, whereby different species utilise different host plants for their caterpillars. In contrast, the driving force behind speciation in Australian peacock spiders appears to be sexual selection. Females choose their mates based on species-specific colours, dances and vibrational “songs”. In addition, we also study the role of hybridisation in the rapid range expansion of wall lizards in Switzerland.

Ithomiini butterflies – genomics of adaptive radiations

Eva van der Heijden, Wellcome Sanger Institute

We study ithomiini butterflies in partnership with collaborators in Ecuador, Colombia, Brazil, France and the UK. The species richness is highly unevenly distributed in this tribe of South American butterflies. Some ithomiini genera have speciated rapidly in the past million years, whereas their close relatives have speciated at a much slower, more normal pace in the order of millions of years. We use whole-genome sequencing to compare slowly and fast speciating genera to identify drivers of rapid speciation. For example, we study the role of chromosomal evolution. Closely related ithomiini species differ strongly in the number of chromosomes, ranging from 5 to 120 chromosomes. We seek to identify the genomic mechanisms at play that drive chromosomal change and its role in the rapid diversification in some genera.

Ithomiini butterflies form “mimicry rings” with lots of species converging on the same warning colour patterns that birds learn to associate with “do not eat”. We study the genetic basis of the colour pattern differences and the role of interbreeding in facilitating mimicry ring switches.

Peacock spiders - genomics of radiations driven by sexual selection

Jürgen Otto CC-BY-SA 2.0

Peacock spiders have also speciated rapidly but, in contrast to ithomiine butterflies, their differentiation is likely driven by sexual selection. Peacock spider species differ in elaborate male mating displays (https://www.peacockspider.org/). This form of selection has led to almost 100 different species in two sets of evolutionary radiations.

We study the roles of interbreeding and chromosomal evolution in the diversification of the peacock spiders. In addition, we assess the genetic architecture of male mating traits and test if these genes show signatures of rapid evolution, strong selection or gene exchange through interbreeding.

To explore the underlying genomic basis of the species’ reproductive isolation, we work closely with partners at the University of Berkley and the University of Sydney. Using whole-genome sequencing, we study the role of interbreeding in the rapid diversification of peacock spiders, the speed of evolution of different traits.

Opportunities

We are always keen to work with curious and creative evolutionary biologists. If you would like to partner with the team on a new project or become a member of group, please contact Joana Meier by email.

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