Genome-wide assessment elucidates connectivity and the evolutionary history of the highly dispersive marine invertebrate Littoraria flava (Littorinidae: Gastropoda)

Abstract

An important goal of marine population genetics is to understand how spatial connectivity patterns are influenced by historical and evolutionary factors. In this study, we evaluate the demographic history and population structure of Littoraria flava, a highly dispersive marine gastropod in the Brazilian intertidal zone. To test the hypotheses that the species has (1) historically high levels of gene flow on a macrogeographical spatial scale and (2) a distribution in rocky shores that consists of subpopulations, we collected specimens along the Brazilian coastline and combined different sets of genetic markers (mitochondrial DNA, ITS-2 and single nucleotide polymorphisms) with niche-based modelling to predict its palaeodistribution. Low genetic structure was observed, as well as high gene flow over long distances. The demographic analyses suggest that L. flava has had periods of population bottlenecks followed by expansion. According to both palaeodistribution and coalescent simulations, these expansion events occurred during the Pleistocene interglacial cycles (21 kya) and the associated climatic changes were the probable drivers of the distribution of the species. This is the first phylogeographical study of a marine gastropod on the South American coast based on genomic markers associated with niche modelling.

Seascape genetics in a polychaete worm: Disentangling the roles of a biogeographic barrier and environmental factors

“…However, palaeodistribution simulations suggest that P. ponteni distribution was restricted to the southern coast of Brazil during the LGM, expanding northward and southward during the mid‐Holocene. The same pattern was found for other coastal species in Brazil (Ayres‐Ostrock et al, 2019; Cortez et al, 2021), and given the significant change in oceanic temperature and sea level from the LGM to the present (Tierney et al, 2020), such restriction in the distribution is expected. The climatic conditions in the mid‐Holocene along the range of P. ponteni distribution are akin to the present conditions (Steig, 1999).…”

Phylogeographic characterization of the ribbon worm Lineus sanguineus populations from the Southwestern Atlantic (Heteronemertea: Lineidae): a true case of cosmopolitanism

“…LGM onwards. The same pattern was observed in another benthic species, the gastropod Littoraria flava and the polychaete P. ponteni, that experienced a geographical and population expansion from Southeastern South America during the LGM (Cortez et al 2021;Mendes et al 2022).…”