Climate-change driven shift of Tegula atra: Late Pleistocene Patagonian biostratigraphical-paleoceanographical marker

AGUIRRE M.; RICHIANO S.; DONATO M.; FARINATI E.

Viena

Congreso; BioSyst.EU 2013; 2013

Universidad de Viena

Results on the systematic review, morphometric analysis, ancestral areas and multivariate and cladistic methods show that Tegula atra recorded in the marine Pleistocene of Patagonia can be considered an excellent biostratigraphical, paleoclimatic and palaeocenographical tool. In Argentina itwas absent in warmer than present marine settings during the Miocene and Pleistocene (MIS11) but exhibits an excellent and very abundant fossil record exclusive for the Late Pleistocene MIS9, 7 and 5 between Río Negro and southern Santa Cruz provinces during a dominantly cool climatic scenario. It first appeared in the SEP during the late Pliocene (cooling trend), dispersed into the SWA by raf on macroalgae (D. antarctica) during the Late Pleistocene (cooling trend) and became extinct in the Mar Argentino during the Holocene (amelioration trend). Our review and data show that its absence in the SWA is a climate change-driven range shift as a consequence after the LGM and at the Pleistocene/Holocene transition of changes in SST (higher), light (less), nutrient availability (less), extension of cold currents (less) and intensities of winds (less) altogether disadvantageous for the occurrence of D. antarctica,  a successful dispersal by rafting of T. atra and causing direct effects on the physiology and survival of T. atra. We reinforce the strong linkage between earth history-biologclimate change- global circulation-productivity, adds for a better understanding of molluscan taxonomic differences along both sides of the Magellanan province at present, bringing light into the possible origins of some clue individual taxa as a response to the last climatic change cycles, and a need for a return to dispersalist models to explain molluscan assemblages from the Atlantic and Pacific margins of South America.