LE3 .A278 2015

2015

Stewart, Don

Acadia University

Bachelor of Science

Honours

Biology

Biology

The common Blue Mussel, Mytilus edulis, has two distinct gender-associated mitochondrial DNA lineages transmitted through egg or sperm, respectively; a system referred to as Doubly Uniparental Inheritance or DUI. DUI has been proposed to allow for M-type genome-specific adaptations for increased sperm performance. Under this scenario, males are not an evolutionary dead-end for mitochondrial DNA transmission and can be consequently affected by selection pressures. Given the presence of two distinct mitotypes found within the male lineage, a standard male genome (SM-type) and a recently masculinized genome (RM-type), the objective of the study was to determine whether or not the prevalence of one particular mitotype over the other is influenced by the density of a mussel bed. Because RM-type mussels have demonstrated faster sperm swimming speed, we asked whether RM-types would be more prevalent in higher density mussel beds vs. the SM-type. A random quadrat sampling method with a 5x6 grid was used to measure mussel bed density at two sites in Scots Bay – Minas Channel, Kings Co., Nova Scotia. After collection, mussels were sexed via gonadal tissue extraction and females were subsequently discarded. Male gonadal DNA was isolated and used in PCRs and restriction digests of PCR products of the nuclear encoded internal transcribed spacer (ITS) region for species determination. Preliminary identification of male-transmitted mitotypes was obtained through amplification of a portion of the mitochondrial cytochrome oxidase subunit III gene using SM-specific primers. Confirmation of the presence of RM mitotypes was determined by amplification and sequencing of the mitochondrial cytochrome c oxidase subunit I gene for these samples. Despite successfully sampling two populations with different densities, no association between density and ratio of RM to SM mitotypes was found; this may reflect the close geographic proximity of the mussel beds, which are likely connected by a high level of gene flow.

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https://scholar.acadiau.ca/islandora/object/theses:1281