The application of baleen whale genomes in conservation and evolutionary research

• Main Author: Wolf, Magnus
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2023
• Subjects: ddc:570; Balaenoptera musculus; Balaenoptera physalus; baleen whale; baleen whales; Blue whale; Fin whale
• Online Access: http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/75018; https://nbn-resolving.org/urn:nbn:de:hebis:30:3-750186; https://doi.org/10.21248/gups.75018; http://publikationen.ub.uni-frankfurt.de/files/75018/MWolf_Dissertation_BaleenWhaleGenomics.pdf

Baleen whales (Mysticeti) are a clade of highly adapted carnivorous marine mammals that can reach extremely large body sizes and feature characteristic keratinaceous baleen plates used for obligate filter feeding. From a conservation perspective, nearly all baleen whale species were hunted extensively over a roughly 100 years lasting time period that depleted many of the respective whale stocks with so far unknown consequences for e.g. their molecular viability. From an evolutionary perspective, the lack of fossil records together with conflicting molecular patterns resulted in a still unclear and debated phylogeny of modern baleen whales, particularly in rorquals (Balaenopteridae). In this dissertation, I will demonstrate the application of baleen whale genomes to tackle these open questions by using modern approaches of conservation and evolutionary genomics. Conservation genomic aspects of baleen whales were addressed in two projects, both using whole genome data of either an Icelandic fin whale (Balaenoptera physalus) population or multiple blue whale (Balaenoptera musculus) populations to evaluate the impact of the industrial whaling era on their molecular viability. The results suggest a substantial drop in effective population size of both species but also a lack of manifestation in genotypes of the fin whale population when compared to the blue whale populations. Especially the rare and short runs of homozygosity (ROH), usually indicative for inbreeding, suggest frequent outcrossing in fin whales while all analyzed blue whale populations featured long and frequent ROH. In addition to these analyses, genome data of blue whale populations was further used to evaluate if northern hemisphere blue whales diverged into different subspecies. Population genetic and gene flow analyses showed clearly separated and well isolated populations in accordance with their assumed geographical distance. In contrast, the genome-wide divergence between all blue whale populations was low compared to other cetacean populations ...