Genetic Allee Effects for Controlling Invasive Populations.

Invasive pests threaten food security and devastate ecosystems. A universal problem in their management is that small populations can easily evade detection. This makes identifying new incursions challenging and complicates efforts to eradicate or contain established populations. If newly founded populations exhibited a strong Allee effect, small populations would tend towards extinction and most new incursions would go extinct without the need for detection or intervention. Of course, invasive species rarely exhibit strong Allee effects, but new genetic technologies make it conceivable to impose one. Here we consider how introduction of genetic load can cause a genetic Allee effect that reduces the establishment probability of small founder populations. Using numerical and individual-based modelling, we examine the fate of populations sampled from a larger invasive source population carrying deleterious recessive alleles. Our analysis reveals that the genetic load unmasked by founding can dramatically reduce the establishment probability of small populations across a wide range of parameter space. A sterile mutation effect is more effective than a lethal mutation effect, but X-linkage offers minimal benefit over autosomal inheritance. Although extinction of newly founded populations is a common outcome, it may be challenging to achieve in species with very high reproductive outputs. Distributing deleterious recessive alleles across a large number of loci at low frequencies was more effective than distributing them across fewer loci at higher frequencies. Our findings suggest that driving deleterious recessives into a source population may render it less prone to establish in new areas.