Resumen:
One of the most relevant characteristics of the extant Southern Ocean fauna is its resiliency
to survive glacial processes of the Quaternary. These climatic events produced catastrophic
habitat reductions and forced some marine benthic species to move, adapt or go extinct.
The marine benthic species inhabiting the Antarctic upper continental shelf faced the Quaternary
glaciations with different strategies that drastically modified population sizes and
thus affected the amount and distribution of intraspecific genetic variation. Here we present
new genetic information for the most conspicuous regular sea urchin of the Antarctic continental
shelf, Sterechinus neumayeri. We studied the patterns of genetic diversity and structure
in this broadcast-spawner across three Antarctic regions: Antarctic Peninsula, the
Weddell Sea and Ade lie Land in East Antarctica. Genetic analyses based on mitochondrial
and nuclear markers suggested that S. neumayeri is a single genetic unit around the Antarctic
continent. The species is characterized by low levels of genetic diversity and exhibits a
typical star-like haplotype genealogy that supports the hypothesis of a single in situ refugium.
Based on two mutation rates standardized for this genus, the Bayesian Skyline plot
analyses detected a rapid demographic expansion after the Last Glacial Maximum. We propose
a scenario of rapid postglacial expansion and recolonization of Antarctic shallow areas
from a less ice-impacted refugium where the species survived the LGM. Considering the
patterns of genetic diversity and structure recorded in the species, this refugium was probably
located in East Antarctica.