INVESTIGADORES
BROGGER Martin Ignacio
congresos y reuniones científicas
Título:
Last glacial maximum and its effects on the marine fauna of Southern South America: the case of Arbacia dufresnii
Autor/es:
DE LA PUENTE, B.; POULIN, E.; GERARD, K.; BROGGER, M.I.; MARTÍNEZ, A.; DÍAZ, A.
Lugar:
Moscú
Reunión:
Conferencia; 10th European Conference on Echinoderms; 2019
Resumen:
The Magellan biogeographic Province is an extensive zone of South America that comprise from ~ 42°S in the Pacific to ~ 41°S in the Atlantic. Both sectors are united by the Cape Horn Current, originated in the Southeast Pacific coast around 42°S, flows southward and then eastward to join with the Falkland/Malvinas Current at the Atlantic. Nevertheless, both coast present differences in their geomorphology, such as a segregated coastline with a complex landscape of gulfs, fjords, and channels in the Pacific, while the Atlantic sector has a coastline formed by huge plains in almost all its extension. Moreover, the continental shelf of the Southeast Pacific is narrower (~ 6.24 km), than the continental shelf of the Atlantic, which is the widest in the world (~ 440 km). The marine benthic fauna of this extensive province has been described as adapted to cold temperate and subantarctic zones due to the effects of the tectonic and climatic processes, such as the Quaternary glacial cycles and principally the Last Glacial Maximum (LGM). Which promote a global decrease in sea level (~ 130 m) and the formation of an ice layer in the southern tip of South America that advanced up to 43ºS by the Pacific coast. This background allows proposing that the effect of the LGM should be greater for the Pacific marine benthic fauna than the Atlantic. Under the Quaternary biogeographic model of contraction and expansion, using molecular tools (mtDNA COI), we investigate the effect of the LGM on the genetic diversity of the benthic marine fauna on both sides of the Magellan Province. We study the echinoid Arbacia dufresnii, a shallow subtidal species of this great Province that also has a population further north in the southeast Pacific coast, at ~ 39ºS (Los Molinos), we assessed the diversity/structure genetic and gene flow pattern. Our analyses indicate that A. dufresnii presents a population expansion signal and low levels of genetic diversity on both sides of the Magellan Province. However, Los Molinos locality has a greater genetic diversity and environmental stability inferred that allow us to propose that could act as a source of diversity for A. dufresnii during the LGM. Moreover, we detect an incipient structure between Los Molinos and the Pacific Magellan Province, probably due to the biogeographic break described at the 42°S and an asymmetric pattern of gene flow. We propose that the synergy of the effects of the LGM in the Pacific was similar to the Atlantic sector, due to its extensive exposed continental shelf and, that the presence of a larval stage allows connectivity and generates genetic homogeneity among the different localities.