The Genetic Basis of Local Adaptation to Thermal Stress in the Intertidal Copepod Tigriopus Californicus /

Populations of the intertidal copepod, Tigriopus californicus, vary in their tolerance to thermal stress. In this study, the genetic basis of these differences was examined by generating interpopulation hybrids between a northern and southern population; hybrids were then exposed them to multiple generations of heat stress. At each generation, changes in allele frequency of six candidate genes were monitored. Although allelic frequencies did not change in response to thermal stress, there was evidence of intrinsic selection due to Dobzhansky-Muller incompatibilities against the southern allele in several of these genes. This observation has important implications for understanding genetic incompatibilities between populations, and the trade-offs between thermal tolerance and overall fitnes