The Sex Specific Genetic Variation of Energetics in Bank Voles, Consequences of Introgression?

Interaction between mitochondrial and nuclear genomes is expected to affect energetic phenotypes of traits linked to mitochondrial physiology, further influencing the fitness. A rodent, the bank vole (Myodes glareolus), has a population structure completely or partially introgressed with mitochondria from its relative, the red vole (M. r utilus). Females that carried either bank vole mitochondria or mitochondria from the introgressed species were repeatedly mated with males of both mtDNA types. We found that in males, but not in females, morpho-physiological phenotypes are affected by sire type, causing decreases in body mass (BM) and basal metabolic rate (BMR; including BM corrected, rBMR) in individuals sired by fathers carrying introgressed mitochondria. Higher effect sizes for the proportion of additive genetic variation (and 5.6, 1.9 and 3.6 times higher narrow sense heritability for BM, BMR and rBMR, respectively), and lower for proportion of environmental variation were detected in progeny of non-introgressed males. Our data indicate that co-adapted and possibly co-introgressed nuclear genes related to energetic physiology have an important role in adaptation to the northern conditions in bank voles, and that sex linked nuclear genes are a potential source for variation in basal metabolic rate.