inbreeding depression
Facon B, Hufbauer RA, Tayeh A, Loiseau A, Lombaert E, Vitalis R, Guillemaud T, Lundgren JG & Estoup A 2011 Inbreeding depression is purged in the invasive insect Harmonia axyridis. Curr Biol 21:424-427.
- bottlenecks in population size reduce genetic diversity and increase inbreeding, which can lead to inbreeding depression
- it is thus puzzling how introduced species, which typically pass through bottlenecks, become such successful invaders
- bottlenecks of intermediate size can actually purge the alleles that cause inbreeding depression
- for purging to occur, the reduction in population size should be of intermediate intensity (i.e., ranging from 40–300 individuals, depending upon intensity of selection) and the mutations leading to inbreeding depression should be strongly deleterious and highly recessive
- the greatest purging occurs when inbreeding depression is mainly due to mutations that are both strongly deleterious and highly recessive
- inbreeding depression in native populations of HA probably stems from highly recessive and strongly deleterious mutations
- invasive populations often have higher performance than native ones even when reared in a common environment
- this has been attributed mainly to adaptation to the new range
- however, a purging of inbreeding depression could explain, at least partly, the increase in performance without invoking local adaptation
- a shift toward selfing has been observed in some invasive plants
- a reduction in genetic load during invasions could thus promote a shift from outcrossing toward selfing in invasive plant populations
