Color polymorphism in a Hawaiian spider species: Using genomic tools to identify the molecular basis of adaptation

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Color polymorphisms in plants and animals are of major biological significance and have been subject to considerable research. While the evolutionary importance of coloration is undisputed and well understood, little is known about its molecular basis. Here, I propose a research project to elucidate the genetic basis of an adaptive color polymorphism in a spider species, the Hawaiian happy face spider Theridion grallator. All populations of this species are distinguished by a balanced color polymorphism, which is maintained by negative frequency dependent selection. Theridion grallator is an ideal model for unraveling the molecular basis of polymorphic coloration and for research into the convergent evolution of polymorphisms. It has been well studied over the past decades, and several genomic and molecular genetic resources have been developed for the species. The color polymorphism has a simple genetic basis and morphological architecture, yet has arisen independently at least two times on different islands of the Hawaiian archipelago. Moreover, several other spider species, both closely and distantly related, have developed convergent color polymorphisms. I aim to identify the causal loci for color variation in the happy face spider and plan to approach this task in two steps. First, I will use a combination of population genomics, different genetic mapping strategies, and ecological field experiments, to identify a set of candidate loci. Second, I will use functional genetic tests to uncover direct associations of gene expression and phenotypic divergence. Besides providing insights into the molecular basis of color polymorphism, my data will contribute to a large collaborative project on adaptive radiations on the Hawaiian Archipelago.