Understanding the evolutionary significance of chromosomal inversions in adaptation and speciation in Littorina marine snails

RUI FARIA

SEAGEN, Associação-Biopolis, CIBIO-InBIO, Vairão, University of Porto, Portugal

ruifaria@cibio.up.pt

Link to onsite registration: TBA

Link to seminar: https://umontpellier-fr.zoom.us/webinar/register/WN_sELZIS1LR_CJrX_dW1elVQ

The existence of chromosomal inversions has been known since the beginning of genetics. Because inversions can have both direct (e.g., altering genes at breakpoints) and indirect effects (as recombination modifiers) on fitness, they have the potential to play a major role in evolutionary processes such as adaptation and speciation. For example, it is widely recognized that inversions can facilitate adaptation by suppressing recombination in heterokaryotypes, keeping beneficial alleles at multiple loci together within arrangements. However, inversions are influenced by many interacting processes (for example, reduced recombination also increases the effects of genetic drift). Thus, understanding the underlying mechanisms as well as the sequence of evolutionary events by which inversions play a role in adaptation or speciation is challenging. As result, despite the increasing genomic evidence for the presence of polymorphic inversions across many systems, their evolutionary significance is not yet fully understood.

In order to contribute to fill this gap, I will present the collective efforts of the Littorina Research Community to understand the role of inversions in adaptation and speciation in Littorina marine snails. By combining genomic and phenotypic data from multiple natural hybrid zones across the Littorina saxatilis distribution range with QTL analyses, I will argue that: i) some inversions are enriched for SNPs showing strong differentiation between ecotypes; ii) traits that evolved in parallel in multiple populations facing similar divergent pressures map to inversions; iii) inversions contribute to (rapid) ecotype divergence, but their role in completing speciation in this system is less clear; and iv) some inversions overlap with inverted regions recently identified in L. fabalis, suggesting that they could be relatively old. Finally, I will describe our current efforts trying to infer the evolutionary history of these inversions and put our results into a wider taxonomic context aiming to understand the evolutionary significance of inversions across the tree of life.

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