SEMINAR: MBF602 9/16/11 S/A 103 12 NOON Kevin Brix: Evaluation of Pre- and Post-Zygotic Isolation in Two Populations of the Euryhaline Fish, Cyprinodon variegatus

["Maxine Williams" <mwilliams@rsmas.miami.edu>]

MBF602 9/16/11 S/A 103, 12 NOON Student Speaker Kevin Brix

Evaluation of Pre- and Post-Zygotic Isolation in Two Populations of the Euryhaline Fish, Cyprinodon variegates

The euryhaline pupfish Cyprinodon variegatus variegatus (Cvv) occurs along the Gulf and Atlantic coastlines.  A freshwater pupfish population given subspecies status (Cyprinodon variegatus hubbsi; Cvh) is found in six lakes in central Florida.  Designation of Cvh as a separate species has significant conservation implications for this population. Within the lakes, Cvh only occurs in a narrow niche of sandy shoreline due to predation pressure and competitive exclusion  in other habitats.  Eutrophication and urban development have led to loss of much of the sandy shoreline habitat.  Cvh is currently not afforded any protection due to its status as a sub-species.  The current study evaluated whether pre- and/or post-zygotic isolation has developed between Cvv and Cvh.  In choice mating experiments, Cvv females bred almost exclusively with conspecific males.  In no-choice mating experiments hybrid embryos had significantly lower hatching success compared to embryos from con-specific matings.  Overall, results indicate relatively strong but incomplete pre- and post-zygotic isolation has developed between Cvv and Cvh.  These results along with other data on differences in osmoregulatory capacity and genetic distance will be used to determine whether Cvh should be designated as a separate species or an evolutionarily significant unit and afforded greater environmental protection.

 

Kevin Brix

University of North Florida, B.S. Biology 2008

Entered Ph.D. Program Fall 2009

Advisor: Martin Grosell