Aceptado 28/12/19: "Quaternary ice sheets and sea level regression drove divergence in a marine gastropod along Eastern and Western coasts of South America"

FERNÁNDEZ IRIARTE P.; GONZALEZ-WEVAR C.

Scientific Reports

Nature Publishing Group

Año: 2020 vol. 10

2045-2322

The southern South American coastline represents a remarkable area to evaluate how Quaternary glacial processes impacted the demography of the near-shore marine biota. Here we present new phylogeographic analyses in the pulmonate Siphonaria lessonii across its distribution, from northern Chile in the Pacific to Uruguay in the Atlantic. Contrary to our expectations, populations from the southwestern Atlantic, an area that was poorly impacted by ice during glacial periods, exhibited low genetic diversity and evidence of recent expansion, as recorded in heavily ice-impacted areas along the Pacific Magellanic margin. We propose that Atlantic and Pacific shallow marine hard substrate benthic species were differentially affected during the Quaternary in South America. At higher latitude of the southeastern Pacific, ice-scouring drastically affected S. lessonii populations compared to non-glaciated areas along the Chile-Peru province were the species was resilient. In the southwestern Atlantic, S. lessonii populations would have been dramatically impacted by the reduction of near-shore rocky habitat availability as a consequence of glacioeustatic movements. The increase of gravelly and rocky shore substrates in the southwestern Atlantic supports a hypothesis of glacial refugia from where the species recolonized lower latitudes across the Atlantic and Pacific margins.