Genetic rescue is an increase in population growth caused by the introduction of new genetic variation through gene flow. Increases in population growth could be caused by a recovery from inbreeding depression or through adaptive evolution or both. Genetic rescue is a form of evolutionary rescue whereby the gene flow is the evolutionary force that results in population growth.

Genetic rescue has the potential to become a powerful means to conserve small, isolated, and declining populations. 

Human-assisted gene flow for the purpose of genetic rescue has been used in a handful of species of conservation concern. However, this controversial management action is often limited by concerns over outbreeding depression or other risks.

We are working towards a better understanding of genetic rescue through experiments, genomic data, meta-analyses, and theory and aim to apply what we've learned to species of conservation concern. 

We are interested in accurately predicting the conditions that lead to genetic rescue such as level of inbreeding depression, amount of gene flow, and level of divergence between recipient and source populations. We are also interested in determining the underlying genomic architecture of the fitness effects of gene flow. For example, is genetic rescue caused by a genome-wide increase in heterozygosity or by the masking of deleterious recessive alleles?

We have carried out a variety of gene flow manipulation experiments using Trinidadian guppies, and now Eastern mosquitofish, as model species for conservation-motivated experimental evolution. Complete citations of our primary literature on the topic of genetic rescue may be found here.

Ultimately, we strive to apply an improved understanding of genetic rescue to ‘boots on the ground’ conservation of imperiled species. We are currently involved in the design and implementation of assisted gene flow management actions in several species of conservation concern. In Eastern massasauga rattlesnakes and Arkansas darter we are using genomic data to screen populations for signs of recent inbreeding and inbreeding depression which will inform which populations, if any, stand to benefit from assisted gene flow. In the Mitchell’s Satyr Butterfly we are testing for outbreeding depression in lab experiments before advising this strategy be carried out in the wild. In the Florida Scrub-Jay we are in the later stages of actively monitoring the genomic and demographic consequences of assisted gene flow in a small, isolated population on the Atlantic coast.

We are always interested in consulting and/or collaborating with conservation practitioners who are considering assisted gene flow for the purpose of genetic rescue. We have developed genomic tools for screening ideal recipient and source populations and for monitoring the outcomes of assisted gene flow in multiple species. Please contact sfitz@msu.edu if you would like to discuss this topic for the species you are working on.