On the expected relationship between inbreeding, fitness, and extinction

Abstract

-We assessed the expected relationship between the level and the cost of inbreeding, measured either in terms of fitness, inbreeding depression or probability of extinction. First, we show that the assumption of frequent, slightly deleterious mutations do agree with observations and experiments, on the contrary to the assumption of few, moderately deleterious mutations. For the same inbreeding coefficient, populations can greatly differ in fitness according to the following: (i) population size; larger populations show higher fitness (ii) the history of population size; in a population that recovers after a bottleneck, higher inbreeding can lead to higher fitness and (iii) population demography; population growth rate and carrying capacity determine the relationship between inbreeding and extinction. With regards to the relationship between inbreeding depression and inbreeding coefficient, the population size that minimizes inbreeding depression depends on the level of inbreeding: inbreeding depression can even decrease when population size increases. It is therefore clear that to infer the costs of inbreeding, one must know both the history of inbreeding (e.g. past bottlenecks) and population demography.inbreeding / extinction / conservation / genetic load / deleterious mutation

Bat colony size reduction coincides with clear-fell harvest operations and high rates of roost loss in plantation forest

“…However, the impacts of clear-fell harvest and consequent roost loss may mean that plantations are home to bats with low reproductive success (Arnold 2007;Brigham and Fenton 1986;Sedgeley and O'Donnell 2004) that are resident in small colonies. The small colony sizes within plantation forests indicate populations may be more vulnerable to local extinction than those in other habitats where colony sizes are larger (O'Donnell 2002;Theodorou and Couvet 2006). We found fewer roosts and smaller roosting ranges were used after clear-fell harvest operations, indicating roosting habitat is reduced, and smaller colony sizes occur post-harvest.…”

“…C. tuberculatus tend to form socially isolated roosting groups with small exclusive roosting areas, and therefore if a group's roosting area was largely destroyed it may have limited opportunities to integrate with members of a nearby area (O'Donnell 2000a;Sedgeley and O'Donnell 2004). Such isolation increases their likelihood of local extinction (Theodorou and Couvet 2006).…”

Temperature effects on life history traits of two sympatric branchiopods from an ephemeral wetland

“…At higher temperature, E . braueriana produced much more hermaphroditic eggs that provide faster population growth since all emerging individuals could provide offspring themselves [37]. However, hermaphroditism goes along with reduced genetic heterozygosity [38, 39].…”

“…Limnadia lenticularis (Linnaeus, 1761) [48], which has reduced genetic diversity upon extreme inbreeding situation but is advantageous for colonization [49, 50]. Dioecious organisms, in contrast, have relieved inbreeding and elevated fitness by gonochoric reproduction (cross-fertilization) between males and females [37], e.g. Lepidurus apus lubbocki Brauer, 1873 [48].…”

Historical and modern neutral genetic variability in Mednyi Arctic foxes passed through a severe bottleneck

“…Small and/or isolated populations often show lower genetic variability compared with widely distributed ones in large continuous habitats (Frankham, ; Keller & Waller, ). Demographic bottlenecks result in a loss of genetic variation and increased inbreeding (Wright, ; Theodorou & Couvet, ).…”