Whiteley et al. (2015) review genetic rescue (GR), or the increase in population fitness (growth) owing to immigration of new alleles, in a new paper in TREE.
Genetic rescue is a controversial and hasn’t been applied to any great extent in conservation efforts. In small populations of conservation concern, a small number of individuals introduced into an isolated population could restore genetic diversity and mask inbreeding depression. But, debate has centered on:
whether translocation of individuals or alleles into small, imperiled populations will have the desired effect of increasing population growth rates and maintaining a diverse array of local populations, or reduce population fitness through outbreeding depression and decrease biodiversity by homogenizing distinct gene pools.
The authors point to recent work in which re-establishing gene flow among populations that were recently connected will increase fitness (e.g., Hwang et al. 2011).
Genomic approaches will aid in the implementation and effectiveness of GR by improving the ID of the best populations or even individuals for GR and monitoring the outcome of GR attempts with adjustments implemented as necessary.
Hwang AS, Northrup SL, Alexander JK, Vo KT, Edmands S (2011) Long-term experimental hybrid swarms between moderately incompatible Tigriopus californicus populations: hybrid inferiority in early generations yields to hybrid superiority in later generations. Conserv Genet, 12, 895-909