The functional impacts of structural genomic variation on life-history evolution

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Identifying the genetic basis of adaptive phenotypic traits is a major focus of modern evolutionary biology. To date, this work has concentrated on changes in individual base pairs, called single nucleotide polymorphisms. Yet, genomes are a more complex, and many differences between individuals, populations and species are in the form of structural changes. For example, these can be duplications of genes, deletions of parts of the genome or changes in the direction of certain regions. While such structural genetic variants are numerous and thought to be a crucial aspect of genetic diversity, very little is known about how they contribute to adaptive evolution. The main reason for this fundamental knowledge gap is that technologies to study such structural changes have not been widely accessible until recently. In my Fellowship, I will use novel technologies and analytical approaches to dissect the functional role of structural genetic variants in adaptive evolution. I will apply these to an exciting and ideal system, the divergence in life-history strategies in European lampreys. European lampreys belong to a primitive lineage of jawless vertebrates that show up to three distinct adult life histories: they either 1) migrate into the ocean to feed parasitically on other fish, before returning to rivers to spawn and die; 2) migrate into freshwater lakes to feed parasitically before returning rivers to spawn and die; or 3) they remain their entire adult life in their home river, and rapidly mature, spawn and die, without ever feeding as adults. These alternative life histories are widespread across Europe and can often be found to co-exist in the same river and even interbreed, thus providing a powerful system to identify the genetic differences underlying their evolution. I will identify structural variants that distinguish these life-history forms and determine how their evolutionary impact differs from single nucleotide changes. Furthermore, to understand how structural variants lead to changes in adaptive phenotypes, I will investigate their impact on gene regulatory variant in different tissues. Thereby, the proposed research will strongly contribute to answering a fundamental knowledge gap in our mechanistic understanding of evolution: how important are structural genetic variants for adaptive evolution?