Genomics of rapid speciation and adaptation
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
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, by assembling many reference genomes, 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.
Another focus is on the role of hybridisation (interbreeding). While interbreeding between species mostly leads to hybrids with low fitness, it can sometimes be beneficial by enriching the genetic diversity and thus providing the fuel for rapid adaptation or speciation.
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.
Different parts of this project are led by Patricio Salazar (fieldwork), Eva van der Heijden (genetics of colour pattern differences), Karin Näsvall (chromosomal evolution), Jonah Walker (hybridisation) and Joana Meier.
Peacock spiders - genomics of radiations driven by sexual selection
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 speed of evolution and the genetic architecture of male mating traits. This integrative project combines comparative genomics and population genomics with sensory ecology.
Rapid range expansion of wall lizards in Switzerland
Invasive species are on the rise, as human activity has increasingly facilitated their spread across the globe. However, most introduced species do not become invasive. Understanding why and how species spread rapidly is thus of high importance.
In the past two decades, wall lizards (Podarcis muralis) have rapidly expanded their distribution range in Switzerland. Wall lizards are native in Switzerland, but many of the lizards in the rapidly spreading populations look different to the native ones, indicating that they might be of a different subspecies. We study if the rapidly spreading wall lizards represent native, introduced or hybrid subspecies. Hybridisation can facilitate rapid adaptation and rapid range expansion by enriching the genetic diversity. In a preliminary study around Lake Thun, we found that the rapidly spreading populations are all admixed between 3-4 subspecies of wall lizards, including the native lineage, Italian wall lizards and other lineages from South of the Alps. These lineages are multiple million years divergent but are still able to hybridise. We are currently investigating if this finding is a general pattern, and if and how admixture contributed to the rapid range expansion of wall lizards across Switzerland.
This project is led by Anna Orteu, Arif Maulana and Joana Meier and carried out in collaboration with researchers from the KARCH (Swiss Reptile and Conservation Centre) and the Lund University in Sweden.
Public courses and seminar series
Speciation Genomics Course
Together with Mark Ravinet (University of Nottingham), Joana Meier has been teaching a course on speciation genomics with Physalia. The course takes the attendees all the way from raw Illumina reads to finding population structure, demographic modeling and identifying genomic regions with signatures of selection or introgression. As part of this course with we have generated a public how-to-guide.
Lepidoptera Seminar Series
Together with Gabriela Montejo-Kovacevich (University of Cambridge) and Luca Livraghi (George Washington University), we run a seminar series on Lepidoptera research, short Lepinar. We host a Lepinar every other week on Mondays at 4 pm UK time. More information here. If you would like to join the mailing list, subscribe here.
Speciation Seminar Series
As part of the network for Integration of Speciation Research (IOS), we are running a monthly seminar series on speciation research. In order to facilitate participation across time zones, we alternate the time of the day these seminars take place. The IOS network will also host a database on speciation case studies and provide networking opportunities in the form of workshops. It is financed by the European Society of Evolutionary Biology and the committee includes eleven researchers from 10 Universities from different countries. Everyone interested in speciation should sign up to the mailing list.
Join our team
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.
Dr Joana Isabel Meier
Royal Society University Research Fellow and Group Leader
My main research focus is on speciation and evolutionary genomics. Why do some taxa rapidly generate new species, whereas others remain species-poor? I am particularly interested in the role of interbreeding and chromosomal rearrangements in rapid speciation and adaptation.
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