Functional explanation of extreme hatching asynchrony: Male Manipulation Hypothesis
Metadata
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Soler Cruz, Manuel; Ruiz Raya, Francisco; Sánchez Pérez, Lucía; Ibáñez Álamo, Juan Diego; Soler, Juan JoséEditorial
Science Press
Materia
Brood reduction Food allocation Hatching asynchrony Male manipulation hypothesis Sexual differences in food allocation Turdus merula
Date
2022-08-25Referencia bibliográfica
Manuel Soler... [et al.]. Functional explanation of extreme hatching asynchrony: Male Manipulation Hypothesis. Zoological Research, 2022, 43(5): 843-850. doi: [10.24272/j.issn.2095-8137.2021.455]
Abstract
Hatching asynchrony in birds is considered an
adaptation to facilitate brood reduction because
under conditions of food scarcity, the smallest
nestling usually dies soon after hatching, thereby
minimizing parental effort. However, in species with
extreme hatching asynchrony, the last hatchlings
paradoxically experience a very low probability of
survival and death can take so long that it can hardly
be considered an adaptation. Here, we propose and
experimentally tested a new adaptive hypothesis
explaining the brood reduction paradox, namely the
“Male Manipulation Hypothesis”. Our hypothesis
suggests that by inducing asynchronous hatching,
females increase the feeding requirements of the
brood, which will induce males to increase
provisioning effort. In addition, females may extend
the period of male manipulation by feeding the
smallest nestling just enough to sustain life. Our
study showed that male common blackbirds (Turdus
merula) increased their effort (i.e., number of food
items per hour) in experimental asynchronous
broods compared to synchronous broods, while
females reduced their contribution, as predicted by
the hypothesis.