Understanding genetic limitations to population recovery in endangered marine mammals

Abstract

In small populations, genetic factors can both inhibit their recovery and provide insight into their past. Genomic tools can therefore provide a way to better understand limitations to population recovery in endangered species. In my dissertation I present four clear examples of how genomic tools can directly address questions outlined in recovery planning documents for endangered marine mammals in Canada. I used methylation patterns at genomic positions that have been previously found to respond differently to stressors to demonstrate that methylation patterns may be a tangible means to quantify cumulative effects of stress in wildlife populations using resident killer whales (Orcinus orca) as a case study. I used whole genome sequencing to demonstrate that North Atlantic right whales (Eubalaena glacialis) have lived for thousands of years with smaller effective population sizes than southern right whales (E. australis) from the Southwest Atlantic. These results suggest that basing recovery goals in the North Atlantic on the successful recovery seen in the Southern Oceans may not be appropriate. I used ddRAD sequencing to show that in North Atlantic right whales, a female’s inbreeding coefficient did not correlate with her reproductive fecundity, however all individuals had higher heterozygosity than expected suggesting inbreeding may be leading to increased fetal loss in the population – potentially limiting the growth of the population as a whole. Finally, I designed a GTSeq panel to improve ongoing genetic monitoring of North Atlantic right whales and demonstrated its increased power to resolve familial relationships in the species. Genomic tools can provide invaluable insight to directly address knowledge gaps outlined in recovery planning documents in Canada. While these provide just a few examples for a pair of endangered species, the utility of genomics to inform conservation should be better acknowledged and incorporated in recovery planning for Canada’s Species at Risk.