The Atlantic blue mussel, Mytilus edulis Linnaeus, 1758, exhibits doubly uniparental inheritance of mitochondrial (mt) DNA. Females are usually homoplasmic for a female-transmitted mt genome (the F-type), and males are heteroplasmic for an F-type and a male-transmitted mt genome (the M-type). F-types can undergo “role-reversal” events, resulting in new male-transmitted mtDNA genomes known as recently-masculinized (RM) types that co-occur in populations with evolutionarily older standard-male (SM) types. Phylogenetic analyses have shown that RM-types periodically replace SM types. It has also been shown that sperm with RM mtDNA have greater swimming velocity and more efficient components of the electron transport chain compared to sperm with SM mtDNA, thus leading to the hypothesis that RM sperm may have a selective advantage over SM sperm. The present study examines the distribution of RM and SM mitotypes in male M. edulis (n = 225) from thirteen localities in southwestern Nova Scotia (Canada). The SM-type was more common in all populations, with the proportion of RM-types ranging from 0–24.1%. The highest proportion of RM-types was observed in an aquaculture operation. Analyses of additional populations are required to evaluate the selective pressures affecting the geographic distribution of RM and SM mitotypes in M. edulis.
- 1181 Ekologi, evolutionsbiologi