Genomics of post-bottleneck recovery in the northern elephant seal
A. Rus Hoelzel, Georgios A. Gkafas, Hui Kang, Fatih Sarigol, Burney J. Le Bœuf, Daniel P. Costa, Roxanne S. Beltran, Joanne Reiter, Patrick W. Robinson, Nancy Rotzel McInerney, Inge Seim, Shuai Sun, Guangyi Fan, Songhai Li
Abstract
Populations and species are threatened by human pressure, but their fate is variable. Some depleted populations, such as that of the northern elephant seal (Mirounga angustirostris), recover rapidly even when the surviving population was small. The northern elephant seal was hunted extensively and taken by collectors between the early 1800s and 1892, suffering an extreme population bottleneck as a consequence. Recovery was rapid and now there are over 200,000 individuals. We sequenced 260 modern and 8 historical northern elephant seal nuclear genomes to assess the impact of the population bottleneck on individual northern elephant seals and to better understand their recovery. Here we show that inbreeding, an increase in the frequency of alleles compromised by lost function, and allele frequency distortion, reduced the fitness of breeding males and females, as well as the performance of adult females on foraging migrations. We provide a detailed investigation of the impact of a severe bottleneck on fitness at the genomic level and report on the role of specific gene systems.