In closely related species, understanding the role of genetic incompatibilities in driving speciation is critical. Often, environmental gradients (i.e. elevation, temperature) are often involved in helping drive these incompatibilities, but is difficult to quantify.

Using data from an ongoing long-term experiment, we are investigating the growth and survival of hybrid swordtails grown in experimental tanks along an elevational gradient to understand how environment shapes the phenotype of otherwise genetically identical individuals. If environmental gradients play a major role in driving genetic incompatibilities (through selection for phenotypes best adapted to a particular environment), we predict that hybrids will adopt the dominant phenotype of parental strains at that elevation.  Malakai Olivares conducted her Biology undergrad thesis using a small subset of these data to begin testing this hypothesis, and we are continuing our tagging work with the Rosenthal lab at the University of Padua, Italy in pursuit of answering these questions. This work is conducted at the CICHAZ field station in Calnali, Hidalgo, Mexico.