Investigating the genomic and phenotypic consequences of recurrent whole genome duplication in spiders

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The duplication of genes provides new genetic material that can be used for novel functions, allowing plants and animals to evolve biological innovations and adapt to environmental conditions. Whole genome duplication (WGD) is arguably the most dramatic mechanism for duplication, resulting in the production of a new copy of every gene in the nuclear genome. Around 430 million years ago, spiders and scorpions diverged from a common ancestor that had experienced a WGD. The retained duplicated genes from this WGD event (genes called ohnologs) can still be found in the genomes of the approximately 45,000 species of these animals alive today and may have contributed to their adaptation and diversification. Since then, some families of Synspermiata spiders have undergone at least two additional WGDs within a single lineage, reflecting a similar series of WGDs in vertebrates. This presents an opportunity to compare these events to determine whether there are general principals shaping the outcomes of WGDs and their contribution to animal diversification. In addition, Synspermiata represent a wide diversity of spiders that are understudied and poorly understood Therefore, the aims of this project are to identify spider ohnologs after multiple WGDs, explore whether and how they have contributed to the evolutionary success of these animals, and compare the outcomes of these events to repeated WGDs in vertebrates. We will first collect and carry out the first large scale detailed study of the morphology of Synspermiata spiders to better understand their evolution and phenotypic diversity. In parallel, we will identify the ohnologs that have been retained in spider groups after WGDs by comparing the repertoire and arrangement of the duplicated genes in these animals with relatives where there is no evidence of additional WGDs. As part of this aim, we will sequence the genomes of Synspermiata spiders that have undergone one (Pholcus phalangioides, Scytodes thoracica and Loxosceles reclusa), and two (Oonops pulcher, Segestria senoculata and Dysdera crocata) WGD, as well as the transcriptomes of Caponiidae species with two (Orthonops zebra) or three (Calponia harrisonfordi) WGDs. Since relatively little is known about these spiders this will provide new insights into the biology of these animals as well as their genome evolution. We will then compare the repertoires of genes retained after WGD between spiders and vertebrates to determine whether there are any similarities in the aftermath of these events. This information will help us to better understand the general consequences of WGD and the principles underlying their outcomes in terms of genes being preferentially retained or lost again. Identification of ohnologs will also allow us to ask if these genes have been subject to sub-, neofunctionalisation or specialisation during spider development and if their expression is associated with morphological diversification. Overall our project will provide new insights into the genomes of spiders and how WGDs in these animals have contributed to their morphological evolution. Our data will also allow comparisons to WGD events in other animals, including vertebrates, to better understand the general consequences of these events and their contribution to animal adaptation and diversification.