Selection on many loci drove the origin and spread of a key innovation

Abstract

Key innovations have played a central role in the origins of biodiversity, but their evolutionary origin and genetic architecture are usually unknown. A recent transition from egg-laying to live-birth in Littorina snails provides a rare opportunity to study the origin and genetic architecture of a young innovation. While recognized as one species, live-bearing individuals do not form a single clade in a genome-wide phylogenetic analysis, hinting at two independent origins. However, local genealogical analysis identified numerous genomic regions where samples group according to their reproductive mode. These regions are widespread across the genome, show clear evidence for live-bearer-specific positive selection, and are enriched for genes that are differentially expressed between egg-laying and live-bearing reproductive tissues. Our results show that key innovations can have a polygenic basis, and that their historical origins can be obscured by a complex demographic history.

Rapid growth and the evolution of complete metamorphosis in insects

“…Bringing together the developmental and the adaptive evolution perspective on complete metamorphosis will be an important future challenge. This should allow for understanding genetic changes and their order that were required to result in this key innovation of the pupa (39). It is worth noting that complete metamorphosis in the holometabolous insects happens when growth has ceased.…”

Genomics of Neotropical biodiversity indicators: two butterfly radiations with rampant chromosomal rearrangements and hybridisation

“…IQtree2 was used to produce phylogenetic trees in windows across the genome (one 20kb window every 200kb) and to calculate gene concordance factor between these window-trees and the whole-genome phylogenetic tree (103). TWISST (104) and TWISST'nTERN (105) were used to analyse tree discordance across the genome.…”

Chromosomal inversion polymorphisms are widespread across the species ranges of rough periwinkles (Littorina saxatilis and L. arcana) Running title: Widespread inversions in Littorina

“…The dataset used for this study was gathered for a phylogenetic study of the L. saxatilis species complex (Stankowski, Zagrodzka, Galindo, et al, 2023;Stankowski, Zagrodzka, Garlovsky, et al, 2023). Snails were collected between 2014 and 2020, by several different collectors, from 18 locations across the North Atlantic (Figure 1a; Table S1).…”