The first hypothesis is the "sexy son" hypothesis which asserts that although females experience an initial reproductive loss with their first generation, the reproductive success of the second generation compensates for the initial loss.
The second generation of males is thought to be privileged because it will inherit the increased mating ability, or attractiveness, from their fathers and thus will have high success in procuring mates upon maturation.
Since these "sexy sons" are projected to have heightened reproductive success, the secondary female's reproductive success in turn improves.
Some researchers, however, have refuted this theory, stating that offspring born to secondary females suffered from poor nutrition, which resulted in shorter tarsi and lower weights than the progeny of primary and monogamous females.
These phenotypic traits contribute to lesser success in mate acquisition, rejecting the “sexy son” hypothesis.
The first hypothesis is the "sexy son" hypothesis which asserts that although females experience an initial reproductive loss with their first generation, the reproductive success of the second generation compensates for the initial loss. The second generation of males is thought to be privileged because it will inherit the increased mating ability, or attractiveness, from their fathers and thus will have high success in procuring mates upon maturation. Since these "sexy sons" are projected to have heightened reproductive success, the secondary female's reproductive success in turn improves. Some researchers, however, have refuted this theory, stating that offspring born to secondary females suffered from poor nutrition, which resulted in shorter tarsi and lower weights than the progeny of primary and monogamous females. These phenotypic traits contribute to lesser success in mate acquisition, rejecting the “sexy son” hypothesis.
European pied flycatcher