There are an estimated 10 vaquita porpoises left in the world—but they won’t be doomed to extinction based on inbreeding, according to a new genetic study by Jacqueline Robinson and colleagues. Historically, long-term vaquita populations have been small, and as a result their genome-wide diversity has been low but stable for tens of thousands of years, the researchers found, with vaquita individuals remaining healthy and able to breed despite accumulating some weakly deleterious genetic mutations. If the remaining animals can avoid being killed as “bycatch” by fishing gillnets, there is a chance the species will not go extinct, Robinson et al. suggest. The vaquita is one of the world’s most endangered animals, and conservationists are concerned that the vaquita population might suffer a loss of fitness from inbreeding that would keep the species from rebounding. To determine whether inbreeding depression is a reasonable concern, Robinson et al. sequenced and analyzed 20 vaquita genomes taken from archival tissue samples. Based on their findings, the researchers simulated future vaquita population growth under different percentages of bycatch death. If bycatch deaths are stopped entirely, only 6% of the populations in their simulations go extinct. If bycatch death rates decline by just 80%, however, 62% of the simulated populations go extinct. In a related Perspective, Catherine Grueber and Paul Sunnucks discuss the increasing importance of making connections between genome variation and the survival of individuals in wild populations as a part of conservation efforts.
The critically endangered vaquita is not doomed to extinction by inbreeding depression
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