Conservation programs use breeding protocols to increase genomic divergence (by mating genetically dissimilar individuals) in an attempt to circumvent population declines resulting from inbreeding depression. However, disruption of either beneficial gene complexes or local genetic adaptations can lead to outbreeding depression, and thus, there should be a reduction in fitness of individuals at ...

In their recent paper, Sato &Harada (2008) pointed out that for isolated salmonid populations with low effective population size Ne it would be necessary to retain gene flow artificially. Using as a case study small and isolated populations of the freshwater salmonid Kirikuchi charr, Sato & Harada (2008) proposed artificial translocation of individuals within or among populations as a measure t...

Helgason et al. (Reports, 8 February 2008, p. 813) reported a positive association between kinship and fertility in the Icelandic population. We point out that the data further suggest that fertility initially increases with kinship and then decays. This is supported by another large study on the Danish population suggesting a superposition of effects of inbreeding and outbreeding depression on...

Plants that colonize new and/or transient habitats may find themselves ‘out on their own’ with very few individuals of the same species in the vicinity. Opportunities for outbreeding are then very restricted and it is therefore not surprising that many colonizing and pioneer species are self-fertile. Indeed, so common is this correlation that it is often assumed that all such species are mainly...

The nematode Caenorhabditis elegans reproduces primarily by self-fertilization of hermaphrodites, yet males are present at low frequencies in natural populations (androdioecy). The ancestral state of C. elegans was probably gonochorism (separate males and females), as in its relative C. remanei. Males may be maintained in C. elegans because outcrossed individuals escape inbreeding depression. T...

Y OUNG et al. (1994) recently found that a putative transposable element (Lytl) is present at high abundance in the genomes of individuals sampled from a group of red-fruited species of Lycopersicon, and at a much lower abundance in green-fruited species of this genus. Similar or somewhat lower abundances were found in Solanum species believed to be closely related to Lycopersicon, and even low...