Fecundity is usually considered as a trait closely connected to fitness and is expected to exhibit substantial nonadditive genetic variation and inbreeding depression. However, two independent experiments, using populations of different geographical origin, indicate that early fecundity in Drosophila melanogaster behaves as a typical additive trait of low heritability. The first experiment invo...

When previously isolated populations meet and mix, the resulting admixed population can benefit from several genetic advantages, including increased genetic variation, the creation of novel genotypes and the masking of deleterious mutations. These admixture benefits are thought to play an important role in biological invasions. In contrast, populations in their native range often remain differe...

Attempts to conserve threatened species by establishing new populations via reintroduction are controversial. Theory predicts that genetic bottlenecks result in increased mating between relatives and inbreeding depression. However, few studies of wild sourced reintroductions have carefully examined these genetic consequences. Our study assesses inbreeding and inbreeding depression in a free-liv...

Background: Interactions between inbreeding and maternal effects have received little attention, and the effect of maternal age on inbreeding depression in offspring has been almost entirely neglected. Maternal age affects allocation of resources and other materials to offspring, which can affect the fitness consequences of inbreeding. An interaction between inbreeding and maternal age thus has...

We model the evolution of plant mating systems under the joint effects of pollen discounting and pollen limitation, using a dynamic model of inbreeding depression, allowing for partial purging of recessive lethal mutations by selfing. Stable mixed mating systems occur for a wide range of parameter values with pollen discounting alone. However, when typical levels of pollen limitation are combin...

Disease-mediated inbreeding depression is a potential cost of living in groups with kin, but its general magnitude in wild populations is unclear. We examined the relationships between inbreeding, survival and disease for 312 offspring, produced by 35 parental pairs, in a large, open population of cooperatively breeding American crows (Corvus brachyrhynchos). Genetic analyses of parentage, pare...

Hypothesis: Inbreeding depression is manifest in lower sperm production. Organism: Freshwater crustaceans (clam shrimp – Eulimnadia texana), from the southwestern United States, which have high levels of inbreeding. Methods: Comparisons of semi-thin sections of the male gonad among selfed and outcrossed siblings from four families. Results: There was a twofold reduction in sperm production in i...

Measurements of size and asymmetry in morphology might provide early indications of damaging effects of inbreeding or other genetic changes in conservation breeding programs. We examined the effects of inbreeding on size and fluctuating asymmetry (FA) in skull and limb bone measurements in experimental populations of three subspecies of Peromyscus polionotus mice that had previously been shown ...

There are numerous examples demonstrating that selection has greatly influenced phenotypes in wild-harvested species. Here, a significant reduction in horn size in trophy desert bighorn sheep rams over 30 years in a reintroduced population in Aravaipa Canyon, Arizona is documented. After examining the potential effects of a detrimental change in the environment, inbreeding depression, and hunte...

Avoidance of incestuous matings is widely reported across many animal taxa, and the adaptive value of such behavior is explained through inbreeding depression. However, an old and somewhat neglected theoretical result predicts that inbred matings offer another, positive effect on the inclusive fitness of parents: an individual who mates with a relative will help that relative to spread genes id...