New haplotypes found in stranded long-finned pilot whales (Globicephala melas) in the eastern North Atlantic and adjacent waters

Abstract

Long-finned pilot whale (Globicephala melas) mitochondrial (mtDNA) genetic diversity is considered low, especially in the North Atlantic, where only six haplotypes have been recorded using a 345bp portion of the control region. Previous studies have been based on a small number of samples and have not included samples from Ireland or the Netherlands. We utilized mtDNA control region sequencing of individuals stranded around Ireland, Scotland, and the Netherlands between 1995-2019 (n=180) to assess regional diversity. Following alignment of 631bp, nine haplotypes were identified, of which five were newly described (haplotype diversity (h)=0.511). Pairwise tests revealed significant differentiation between the Irish and Scottish samples. Potential confounding factors are discussed but, given the dangers of failing to recognize population structure this needs to be investigated further using nuclear markers and individual-based approaches before population isolation is assumed. The analyzed samples included six mass stranding events. One of the mass strandings reported two haplotypes, confirming mixing of matrilines within a North Atlantic stranding for the first time. This study shows that stranding sample databases are a useful tool for assessment of genetic diversity and provides new insights into genetic diversity of long-finned pilot whale haplotypes in the eastern North Atlantic and adjacent waters.