Population genetic structure of Eleginops maclovinus (róbalo) along the Patagonian coast (40⁰ 54⁰S), evidence of population expansion.

CEBALLOS, SANTIAGO GUILLERMO; LESSA, E. P.; VICTORIO, M. F.; FERNANDEZ, DANIEL ALFREDO

Buenos Aires

Conferencia; SCAR; 2010

SCAR

Nototheniods are a suborder of Perciforms that underwent an impressive adaptive radiation in Antarctic waters. Nowadays, more than hundred and twenty (120) species corresponding to eight (8) families live in Antarctic and sub-Antarctic waters. Three of them, the less derived ones, most likely never experienced Antarctic climate. One of those families, Elegiopidae, is a monoespecific family being Eleginops maclovinus, the only representative, the notothenioid with  the largest latitudinal extended distribution from the Southern tip of South-America to the northern part of Patagonia. This study was conducted along the Argentinean Patagonian Coast analyzing sequences of 835 pb of cytochrome b gene (mtDNA) from 158 individuals collected at San Antonio Oeste, Puerto Madryn, Radda Tilly, Puerto San Julián, Punta María and Beagle Channel. We found 49 variable sites, including 20 singletons and 29 parsimony informative sites, that defined 38 haplotypes. Overall haplotype and nucleotide diversity were 0.90 and 0.0040 respectively (ranging from 0.82 to 0.96 in the former, and from 0.0026 to 0.0054 in the later, at different localities). Both haplotype diversity as well as nucleotide diversity reached the highest values at the two northern localities, SAO and Pto. Madryn. Many haplotypes were shared between several populations across the geographic sampled range. There was also a high number of unique haplotypes (21) almost all of them defined by single nucleotide changes (20), particularly frequents at the southern collecting sites except at Pta. María. The analysis of the sequences revealed low population structure (Fst de Wright and AMOVA). Neutrality test values (D of Tajima and Fs of Fu) were consistently negative for all populations. The unimodal pairwise distribution analysis suggested a recent population expansion. Parsimony tree showed that most of the populations analyzed are polyphyletic, suggesting that the populations have not been isolated long enough to reach reciprocal monophyly.