Digest: Extremes of the mating system continuum are the most evolutionarily stable.

Abstract

Marcondes and Douvas (2024) provide a macroscale insight into the evolution of mating systems in birds. The study shows that resource-defense polygamous lineages are evolutionarily unstable, commonly transitioning into monogamy or going extinct. Surprisingly, lek polygamy is as evolutionary stable as monogamy. While in monogamy both sexes benefit from cooperative behaviour by equally investing in parental care, in lekking systems each sex maximizes their fitness independently: females invest in parental care and males enhance sexually selected traits.