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. 2007 Sep;61(9):2268-73.
doi: 10.1111/j.1558-5646.2007.00177.x.

Viral epizootic reveals inbreeding depression in a habitually inbreeding mammal

Adin Ross-Gillespie  1 , M Justin O'Riain, Lukas F Keller
Affiliations

Viral epizootic reveals inbreeding depression in a habitually inbreeding mammal

Adin Ross-Gillespie et al. Evolution. 2007 Sep.

Abstract

Inbreeding is typically detrimental to fitness. However, some animal populations are reported to inbreed without incurring inbreeding depression, ostensibly due to past "purging" of deleterious alleles. Challenging this is the position that purging can, at best, only adapt a population to a particular environment; novel selective regimes will always uncover additional inbreeding load. We consider this in a prominent test case: the eusocial naked mole-rat (Heterocephalus glaber), one of the most inbred of all free-living mammals. We investigated factors affecting mortality in a population of naked mole-rats struck by a spontaneous, lethal coronavirus outbreak. In a multivariate model, inbreeding coefficient strongly predicted mortality, with closely inbred mole-rats (F> or = 0.25) over 300% more likely to die than their outbred counterparts. We demonstrate that, contrary to common assertions, strong inbreeding depression is evident in this species. Our results suggest that loss of genetic diversity through inbreeding may render populations vulnerable to local extinction from emerging infectious diseases even when other inbreeding depression symptoms are absent.

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Figures

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Kaplan–Meier plots showing the proportional survival of highly inbred (F≥ 0.25) versus outbred and mildly inbred naked mole‐rats (0 ≤F≤ 0.125) through the course of the coronavirus outbreak. Open markers denote censored datapoints. Although represented categorically here, inbreeding was treated as a continuous variable for all regression analyses.
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Comparison of selected variables' effects on the risk of death during the coronavirus epizootic. These values are derived from hazard ratio estimates generated by the proportional hazards model and reflect the change in likelihood of death following a given change of a predictor variable from its base condition (i.e., 0 for continuous variables, females in the case of sex). Age and sex effect estimates shown here apply to nonbreeders only.
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