Genomic and fitness consequences of a near-extinction event in the northern elephant seal
Joe Hoffman’s paper about the genomic consequences of the near extinction of the Northern Elephant seal roughtly 100 years ago. (image by Anchor Lee)
Authors: J. I. Hoffman, D. L. J. Vendrami, K. Hench, R. Chen, M. A. Stoffel, M. Kardos, W. Amos, J. Kalinowski, D. Rickert, K. Köhrer, T. Wachtmeister, M. E. Goebel , C. A. Bonin, F. M. D. Gulland, K. K. Dasmahapatra
Journal: Nature Ecology & Evolution
Abstract: (access from publisher)
Understanding the genetic and fitness consequences of anthropogenic bottlenecks is crucial for biodiversity conservation. However, studies of bottlenecked populations combining genomic approaches with fitness data are rare. Theory predicts that severe bottlenecks deplete genetic diversity, exacerbate inbreeding depression and reduce population viability. However, actual outcomes are complex and depend on how a species’ unique demography affects its genetic load. We used population genetic and veterinary pathology data, demographic modelling, whole-genome resequencing and forward genetic simulations to investigate the genomic and fitness consequences of a near-extinction event in the northern elephant seal. We found no evidence of inbreeding depression within the contemporary population for key fitness components including body mass, blubber thickness and susceptibility to parasites and disease. However, we detected a genomic signature of a recent extreme bottleneck (effective population size = 6, 95% CI = 5–7.5) that will have purged much of the genetic load, potentially leading to the lack of observed inbreeding depression in our study. Our results also suggest that selection against deleterious alleles persisted for several generations after the bottleneck, impeding the northern elephant seal’s demographic recovery. Our study provides comprehensive empirical insights into the intricate dynamics underlying species-specific responses to anthropogenic bottlenecks.
References
Hoffman, J. I. et al. (2024). Genomic and fitness consequences of a near-extinction event in the northern elephant seal. Nature Ecology & Evolution, 1–16. https://doi.org/10.1038/s41559-024-02533-2
