Sex, Mitochondria, and Genetic Rescue

Abstract

Genetic rescue is a potentially effective management tool to offset the effects of reduced genetic diversity in imperiled populations. However, implementation requires complex choices. Here we address the consequences of introducing males versus females, highlighting the possibility that introduced females might lead to maladapted mitonuclear genomes and reduced offspring fitness.

Figure 1. Mitonuclear incompatibility during genetic rescue

(A) When females are introduced during genetic rescue, mitonuclear incompatibilities can be propagated through generations (colored boxes), resulting in reduced fitness, especially in later generations, because females will bring in a novel mitochondrial genome that might be maladapted to the local nuclear genome. (B) Introducing males is less likely to cause mismatch, as their mitochondrial genomes are not transmitted. Each pedigree shows two nuclear chromosomes (linear) and a mitochondrial chromosome (circular). Orange boxes indicate genotypes that are at risk of mitonuclear incompatibilities if a single “mismatched” nuclear allele is sufficient to have a deleterious effect. Red boxes indicate genotypes that are at risk even if both nuclear alleles must be mismatched with the mitochondrial genome to have a harmful effect. Dashed and dotted lines indicate lower risks associated with a lower overall frequency of mismatched alleles.