Graduation Year

2026

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Deby Cassill, Ph.D.

Co-Major Professor

Michelle Green, Ph.D.

Committee Member

Heather Judkins, Ph.D.

Committee Member

Denise Herzing, Ph.D.

Keywords

Conservation biology Reproductive success, Marine mammals, Paternity analysis, Population genetics Conservation Genetics, Climate Change

Abstract

Marine mammals are impacted by hurricanes that may influence reproductive success and genetic diversity. Understanding how populations respond to demographic change is increasingly important as extreme weather events become more frequent. A population of Atlantic spotted dolphins (Stenella frontalis) on Little Bahama Bank in the Bahamas has been observed continuously since 1985. In 2004, two hurricanes struck the region within one month, resulting in the loss of approximately 36% of the population. Population declines can alter the operational sex ratio (OSR), social structure, and encounter rates among potential mates, potentially influencing patterns of reproductive success. Previous molecular studies showed that reproductive success was skewed toward older fused males. Because changes in OSR may alter male access to females, this study evaluated whether patterns of male reproductive success changed following the hurricane-related population decline. DNA isolated from noninvasively collected fecal samples from 12 mom/calf pairs and 32 candidate males were used to conduct paternity analyses. Paternity was confidently assigned (95%) to one fused male, consistent with previous findings that older males have greater reproductive success in this population. Additionally, three males, two fused and one mottled, were identified as the most likely candidate fathers for other calves. Candidate fathers on average were 4-7 years older than the mothers. The identification of a mottled male as a most likely candidate father post-hurricanes is notable because successful males in this population have previously been restricted to the fused age class. These results suggest that demographic disturbances may influence reproductive dynamics and highlight potential genetic consequences of climate-related environmental change in otherwise stable marine mammal populations.

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