Contribution of inbreeding to extinction risk in threatened species

By Barry W. Brook, D. Tonkyn, J. O'Grady, R. Frankham. 2002

325 citations recorded by the source corpus.

Wild populations face threats both from deterministic factors, e.g., habitat loss, overexploitation, pollution, and introduced species, and from stochastic events of a demographic, genetic, and environmental nature, including catastrophes. Inbreeding reduces reproductive fitness in naturally outbreeding species, but its role in extinctions of wild populations is controversial. To evaluate critically the role of inbreeding in extinction, we conducted realistic population viability analyses of 20 threatened species, with and without inbreeding depression, using initial population sizes of 50, 250, and 1000. Inbreeding markedly decreased median times to extinction by 28.5, 30.5, and 25% for initial populations of 50, 250, and 1000, respectively, and the impacts were similar across major taxa. The major variable explaining differences among species was initial population growth rate, whereas the impact of inbreeding was least in species with negative growth rates. These results demonstrate that the prospects for survival of threatened species will usually be seriously overestimated if genetic factors are disregarded, and that inappropriate recovery plans may be instituted if inbreeding depression is ignored.

Subfields: Ecology, Genetics

View Paper: https://www.semanticscholar.org/paper/0cb9f5ea0c2b0a3eec130a4b97d5aebf4e4c9e9f

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Citations in the corpus

The relationship between population size and temporal variability in population size (2004, background): “Inbreeding depression and random genetic drift pose a threat to the persistence of populations of sizes much greater than is generally believed (Franklin, 1980; Schultz & Lynch, 1997; Reed, 1998; Reed & Bryant, 2000; Whitlock, 2000; Brook et al. , 2002; Reed & Frankham, 2003).”
Extinction risk in fragmented habitats (2004, background): “…be ubiquitous in natural populations (Crnokrak & Roff, 1999; Keller & Waller, 2002; Reed & Frankham, 2003) and can have major effects on the persistence of even relatively large populations (Reed & Bryant, 2000; Brook et al., 2002; Reed & Frankham, 2003; J. J. O’Grady et al., unpublished results).”
Inbreeding and extinction: Effects of rate of inbreeding (2003, background): “growth rates and has been implicated in the extinction process of wild populations (Dobson et al. 1992; Mills and Smouse 1994; Newman and Pilson 1997; Saccheri et al. 1998; Westermeier et al. 1999; Oostermeijer 2000; Brook et al. 2002).”
Realistic levels of inbreeding depression strongly affect extinction risk in wild populations (2006, background): “The sole published study across a broad taxonomic range (birds, mammals, plants and reptiles) found a clear reduction in population viability (Brook et al., 2002) by applying a very conservative level of inbreeding depression; the average level found for juvenile survival in captive mammals (Rails e”
What are the best correlates of predicted extinction risk (2004, background): “Brook et al. (2002a) answered the critics, while Reed et al. (2002) concluded that stochastic population models are valuable tools for examining the relative risks of extinction between taxa.”
The rough edges of the conservation genetics paradigm for plants (2006, background): “…1994; 1236 N. J. Ouborg, P. Vergeer & C. Mix © 2006 The Authors Journal compilation © 2006 British Ecological Society, Journal of Ecology, 94, 1233–1248 Brook et al. 2002; Glemin et al. 2003; Armbruster & Reed 2005), the possibilities and limitations of the purging of genetic loads (e.g. Whitlock…”
Genetics and extinction (2005, methodology): “Using realistic computer projections for 20 threatened species, we compared median times to extinction for models with and without inbreeding depression (Brook et al., 2002).”
Genetics in conservation management: Revised recommendations for the 50/500 rules, Red List criteria and population viability analyses (2014, background): “First, inbreeding depression substantially reduces median times to extinction in PVAs for real species in natural environments (Brook et al., 2002; O’Grady et al., 2006).”
Relationship between Population Size and Fitness (2005, methodology): “Using computer simulations, Brook et al. (2002) showed that median extinction times were reduced 24–31% when even conservative levels of inbreeding depression were included in the models.”
Behavioural responses to human‐induced environmental change (2011, background): “This can result in the loss of genetic variation and have negative demographic and genetic consequences (Brook et al., 2002).”
Detecting bottlenecks using BOTTLENECK 1.2.02 in wild populations: the importance of the microsatellite structure (2010, background): “If the genetic side of species conservation is not evaluated, extinction risks will be underestimated and therefore the conservation programs developed would be more likely to fail (Brook et al. 2002; Vucetich and Waite 1999).”
Individual dispersal, landscape connectivity and ecological networks (2013, background): “However, a vast majority of empirical studies confirm that the probability of extinction of a local population is positively related to its isolation, and negatively related to its size (e.g. Ouborg, 1993; Pimm et al., 1993; Hanski, 1999b; Brook et al., 2002; Rodriguez & Delibes, 2003).”
Documented and Potential Biological Impacts of Recreational Fishing: Insights for Management and Conservation (2006, background): “The genetic variability plays a crucial role in the survival of species (Brook et al., 2002; Frankham, 2003; Spielman et al., 2004) and is essential for their potential for successfully evolving in response to short- and long-term environmental changes (Ryman et al., 1995; Reusch et al., 2005).”