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

Marcondes and Douvas [(2024). Social mating systems in birds: Resource-defense polygamy-but not lekking-is a macroevolutionarily unstable trait. Evolution, qpae123] 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 behavior 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.