V.E. Rivera Leon

PhD thesis: Molecular ecology of baleen whales - Past to present (2025)

This thesis advanced our knowledge of the processes that lead to changes in genetic diversity over long and short time scales. Genetic methods were used in two baleen whale species. Chapter One provides a general overview of the knowledge gained employing genetic approaches at the population and individual levels. Chapter Two presents the results of a study focusing on fin whales (Balaenoptera physalus) in the Gulf of California. The work revealed that this population was founded at least two thousand years ago and has remained small since. This population has experienced limited gene flow from conspecific North Pacific populations, resulting in remarkably low levels of genetic diversity. Chapter Four employs mitochondrial DNA sequences from humpback whales (Megaptera novaeangliae) in the Gulf of Maine to assess earlier claims that reproductive output was, in part, correlated to individual maternal ancestry. However, the re-analysis of an extended data set failed to support such correlation.

The work in this thesis also includes evaluations and the development of genetic methods to study baleen whales and other species. Chapter Five evaluates the performance of an algorithm for estimating pedigrees with different levels of additional non-genetic data, such as, relationships inferred from sighting records and age. Even though pedigree estimation is notoriously difficult in natural populations, this study revealed that pedigree inferences greatly benefit from the inclusion of age data. A bioinformatic pipeline was developed in Chapter Three to automate the detection of point heteroplasmy (presence of more than one mitochondrial genome) in large Sanger sequencing datasets.