Although detrimental genetic processes are known to adversely affect the viability of populations, little is known about how detrimental genetic processes in a keystone species can affect the functioning of ecosystems. Here, we assessed how changes in the genetic characteristics of a keystone predator, grey wolves, affected the ecosystem of Isle Royale National Park over two decades. Changes in the genetic characteristic of the wolf population associated with a genetic rescue event, followed by high levels of inbreeding, led to a rise and then fall in predation rates on moose, the primary prey of wolves and dominant mammalian herbivore in this system. Those changes in predation rate led to large fluctuations in moose abundance, which in turn affected browse rates on balsam fir, the dominant forage for moose during winter and an important boreal forest species. Thus, forest dynamics can be traced back to changes in the genetic characteristics of a predator population.
Island ecosystems provide natural laboratories to assess the impacts of isolation on population persistence. However, most studies of persistence have focused on a single species, without comparisons to other organisms they interact with in the ecosystem. The case study of moose and gray wolves on Isle Royale allows for a direct contrast of genetic variation in isolated populations that have experienced dramatically differing population trajectories over the past decade. Whereas the Isle Royale wolf population recently declined nearly to extinction due to severe inbreeding depression, the moose population has thrived and continues to persist, despite having low genetic diversity and being isolated for ∼120 years. Here, we examine the patterns of genomic variation underlying the continued persistence of the Isle Royale moose population. We document high levels of inbreeding in the population, roughly as high as the wolf population at the time of its decline. However, inbreeding in the moose population manifests in the form of intermediate-length runs of homozygosity suggestive of historical inbreeding and purging, contrasting with the long runs of homozygosity observed in the smaller wolf population. Using simulations, we confirm that substantial purging has likely occurred in the moose population. However, we also document notable increases in genetic load, which could eventually threaten population viability over the long term. Overall, our results demonstrate a complex relationship between inbreeding, genetic diversity, and population viability that highlights the use of genomic datasets and computational simulation tools for understanding the factors enabling persistence in isolated populations.
more » « less- Award ID(s):
- 1939399
- NSF-PAR ID:
- 10479407
- Editor(s):
- Nielsen, Rasmus
- Publisher / Repository:
- Oxford Academic
- Date Published:
- Journal Name:
- Molecular Biology and Evolution
- Volume:
- 40
- Issue:
- 2
- ISSN:
- 0737-4038
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/molbev/msad021
