Evolution; International Journal of Organic Evolution · May 8, 2026

Lifetime fitness and annual survival are heritable and highly genetically correlated in a wild primate population

By Tuliozi B, Archie EA, Tung J et al.

The additive genetic variance (VA) of fitness quantifies the expected response to selection. Lifetime reproductive success (LRS) is an effective metric of lifetime fitness in animal population, while time-limited fitness metrics such as annual survival or fertility can help to identify which fitness component-e.g., annual survival or fertility-harbors the most VA in fitness. Here, we estimated the VA and heritability (h2) of LRS and 3 time-limited fitness metrics in a wild female baboon population in Kenya. The most heritable metrics were LRS (h2 = 0.25 [0.18, 0.34]) and annual survival (h2 = 0.23 [0.15, 0.33]). By further partitioning LRS, we were able to show that nearly all the VA for LRS was attributable to survival to first successful reproduction. Furthermore, all fitness metrics examined were highly genetically correlated with each other, supporting the use of time-limited metrics when LRS data are limited. Our analyses predicted faster phenotypic evolution than we have observed, raising the possibility that environmental or social variables masked responses to selection or inflated estimated VA. Overall, our findings reveal a substantial genetic contribution to variation in survival, and in turn, to fitness and contemporary evolution in a long-lived animal.

doi.org/10.1093/evolut/qpag086Open accessPubMed 42101905Mechanisms