Meeting Abstract
Mitochondria act as a major hub coordinating responses to environmental stressors. Atlantic killifish, Fundulus heteroclitus, provide a useful model in which to examine the role of mitochondria in these responses in an evolutionary context. This species is found in marshes along the Atlantic coast of North America, through a steep latitudinal thermal gradient. The northern and southern subspecies of killifish differ in mitochondrial genotype, mitochondrial physiology, and in many whole-organism traits that may be involved in adaptation to their respective environments, including metabolic rate, thermal tolerance, and hypoxia tolerance. Fish with northern and southern mitochondrial genotypes meet and interbreed along the coast of New Jersey and within the rivers of the Chesapeake Bay, resulting in replicate hybrid zones across which there is a steep transition from one mitochondrial type to another. This provides an opportunity to assess the role of mitonuclear interactions in the response to environmental stressors. Genome wide association studies of traits such as thermal tolerance, hypoxia tolerance, and metabolic rate in these hybrid populations point to an important role for genes regulating mito-nuclear communication and cellular metabolic processes. However, there is no association of these traits with variation in the mitochondrial genome, and little evidence of genetic incompatibility between the mitochondrial genome and nuclear-encoded mitochondrial genes. Interestingly, there is some evidence of developmental failure in crosses between southern females and northern males, suggesting a potential role for intrinsic genetic incompatibilities in the maintenance of these hybrid zones.
