Meeting Abstract
The marine teleost Fundulus heteroclitus is distributed along a steep thermal gradient (1°C/degree latitude) in the eastern coast of the United States. The mitochondrial DNA (mtDNA) of this teleost displays two characteristic haplotypes along this gradient. This haplotypes correspond to north, south and a phylogenetic break found at the Hudson River where there is an introgression of northern haplotype into the southern one. We examined mitochondrial activity and mtDNA variation in populations of F. heteroclitus with the aim of gaining insight into evolutionary adaptations to thermal stress. Activity assays were performed in 3 populations 1 from the north (ME), one from the south (GA) and one from the introgression zone (NJ); all populations were acclimated to 12 and 24 degrees. Activity was measured for state 3, complexes 1 and 2, and LEAK at maximum state. No differences where found between populations for any of the assays. However, significant high activity was found across all populations at different acclimated to 12°C temperatures for the assays of state 3 (p=0.0176) and LEAK (p=0.0108). mtDNA sequencing will be performed for the aforementioned populations plus 2 more southern populations (NC and VA) and the sister taxa Fundulus grandis (used as out-group). Data from sequencing will be analyzed to gain information on divergence due to the thermal gradient and possible signatures of natural selection.
