Mitochondrial Haplotype Influences the Impact of Simulated Climate Warming on a Tropical Ectotherm
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While the plight of polar bears in a rapidly warming world is much publicized, recent theory suggests that the organisms likely to be most at risk from rising temperatures are terrestrial arthropods and reptiles inhabiting the tropics. In such ectothermic species, metabolic rate increases exponentially with ambient temperature, and a small temperature increase in a warm environment therefore has a much larger physiological impact than does a comparable temperature increase in a cool environment. In studies recently conducted by my faculty mentors and their students on the Neotropical pseudoscorpion, Cordylochernes scorpioides (Zeh et al. 2012, 2014), it was found that simulated climate warming significantly decreased survival, average values for morphological traits, and level of sexual dimorphism. However, these effects were minor compared to catastrophic consequences for male fertility and female fecundity, pointing to reproduction as the life history stage that is most vulnerable to climate warming. Still to be investigated was the potential for a genetically-based response to elevated temperature. In the study reported here, I took advantage of the coexistence of two sympatric but highly divergent mitochondrial haplogroups in this pseudoscorpion to evaluate the potential impact of mitochondrial sequence variation on fitness traits and response to climate change. For survivorship and sperm production, my results reveal a significant interaction between mitochondrial haplotype and temperature treatment, thus demonstrating genotypedependent effects and the potential for an adaptive evolutionary response to climate warming.