LE3 .A278 2013

2013

Stewart, Don

Acadia University

Bachelor of Science

Honours

Biology

Biology

Mytilus edulis, the Atlantic blue mussel, has an unusual system of mitochondrial DNA (mtDNA) inheritance. In most animals, mtDNA inheritance is exclusively maternal, but in M. edulis, males also inherit paternal mtDNA. Sometimes, pieces of the maternal and paternal mtDNA will recombine and create a “recently-masculinized” or RM mitotype. Studies show that sperm with RM mtDNA swim faster than sperm with standard mitotype (SM) mtDNA. It is hypothesized that faster sperm are at an advantage in dense mussel beds whereas slower but longer-lived sperm are advantageous in sparse mussel beds. Because of this advantage we would expect to see higher RM to SM ratios in dense beds compared to sparse beds. Using primers specific for standard males, polymerase chain reaction and DNA sequencing, the ratio of RM to SM mitotypes in dense versus sparsely distributed beds was examined. Two densely distributed sites in Digby County (N.S.) showed the presence of only SM males. Ocean currents and larvae distribution may explain the absence of RM individuals in Digby County. Therefore, additional sampling was done on the southern and eastern shore of Nova Scotia where two densely populated sites were studied. At Site 3 in Ship Harbour, the frequency of RM males was 24.1% and 75.9% for standard males. At Site 4 in the Halifax area, the frequency of RM males was 13.0% and 87.0% for standard males. This confirms the presence of RM males in these regions of Nova Scotia. To compare this ratio versus sparsely distributed beds, additional sampling is needed. Furthermore, sampling from sites on the southwest coast of Nova Scotia will help determine the geographic distribution of RM mitotype individuals around Nova Scotia

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https://scholar.acadiau.ca/islandora/object/theses:1042