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Delayed plumage maturation in birds and the significance of condition-dependent parental care

Lyu, Nan, Lloyd, Huw, Sun, Yue-Hua
Behavioral ecology and sociobiology 2015 v.69 no.6 pp. 1003-1010
adults, aggression, birds, breeding, evolution, game theory, longevity, males, models, parents, plumage, predation, reproductive performance, researchers, risk, survival rate
Several hypotheses have suggested that delayed plumage maturation (DPM) in male birds evolves to increase crypsis or to deter adult aggression towards inexperienced young males. Here, we present novel extensions of a game theory modeling framework to investigate the evolutionary mechanisms of DPM in a bird population. We reveal that increasing either the maximum survival rate or predation risk can promote the evolution of DPM. Longer life span and transferrable physical condition between breeding years show a significant mutual promotion effect on DPM evolution, and would also enable the evolution of DPM in some species with no reproductive output in year one. Our models indicate that sufficiently high investment on adult plumage is essential for the evolution of DPM, which is consistent with some previous empirical studies. Finally, we highlight the significance of condition-dependent male parental care and provide new insight into how sexual conflict over parental care between parents may influence the evolution of DPM in birds. Our results should help researchers better test the DPM delayed-investment strategy hypothesis with empirical data.