Meeting Abstract
Sequence variation in the mitochondrial genome of animals has recently been discovered to have functional consequences on life-history traits like lifespan and fecundity. Moreover, evidence for “Mother’s Curse” mutations have been found in some systems: mutations in the mitochondrial DNA (mtDNA) that have harmful effects on males, but not on females, due to the maternal inheritance of mitochondria. However, functional mtDNA variation and Mother’s Curse mutations have been explored only in a limited number of traits, even in the model system of the fruit fly (Drosophila melanogaster). Mitochondrial function itself is known to affect a broad range of physiological traits, including neural function and motor performance, and it remains uncertain whether these traits may be affected by variation in mtDNA. In this study, we test a composite measure of behavior, neural function, and motor performance in fruit fly strains that each possess a unique and naturally occurring mtDNA haplotype in an otherwise strictly standardized nuclear genetic background. Using a novel apparatus, we tested each strain for negative geotaxis response (climbing height, a product of time spent orienting and walking) after a controlled drop on to a firm surface. We tested all flies from 5 to 20 days of age, as negative geotaxis in fruit flies is known to show age-related declines that are sensitive to oxidative stress—a key physiological variable in mitochondrial biology. We found differences in negative geotaxis response across age groups, between the sexes, and among strains, and the decline in response with age also varied across strains. Our results demonstrate that variation in mitochondrial DNA alone can have functional effects on a behavioral trait with neural and motor underpinnings.
