Mother’s curse on conservation: assessing the role of mtDNA in sex-specific survival differences in ex-situ breeding programs

For captive breeding to be an effective conservation tool, population fitness needs to be guaranteed according to the latest insights. Preserving genetic diversity has been a major pillar in conservation breeding, as it is a proxy for long-term population viability. Small differences on the DNA level can impact an individual’s overall fitness and when situated on the mitochondrial genome might more specifically affect the process of aging and fertility. In general, mitochondrial DNA is transmitted via the mother. In the process of natural selection, variants beneficial for female fitness will be selected for whereas male-harming variants that are neutral or beneficial in females will never be selected against. This biased selective sieve results in the accumulation of male-harming mutations in the mitochondrial DNA, a process labelled “mother's curse”. Regardless of the susceptibility of zoo populations to “mother’s curse”, mitochondrial-induced fitness effects have remained unstudied within captive breeding programs. While current conservation breeding strategies focus on retaining nuclear diversity, studies that specifically concentrate on aberrant extra-nuclear genetic processes might improve breeding practices. Here, we provide a framework and empirical evidence for the presence of mtDNA-induced sex-specific differences starting from readily available population information. We analyzed whether an individual’s mitochondrial background partly affects survival in a sex-specific manner using studbook data from captive populations representing 16 species. Our results indicate male survival is affected in five maternal lineages on pre- and postnatal level. Additionally, we describe the overall beneficial effects some maternal lineages have over others in terms of survival. These results are of interest in the debate on the maintenance of healthy captive populations and how to further improve safeguarding their genetic diversity for both ex-situ and in-situ conservation. © 2021 Zoological Society of London.

Publication year:2021