Marginal value theorem with exploitation time costs: diet, sperm reserves, and optimal copula duration in dung flies

Article Abstract:

The validity of the marginal value theorem (MVT) was investigated when the costs of time spent in different activities, which the MVT assumes to be constant, is variable. Two models were developed based on the additional costs of time spent for nectar-foraging and predation to replenish energy and proteins expended in mate searching and mating. Assumptions regarding sperm replenishment served to extend the classical MVT model and was able to explain qualitatively the relationship between reproductive behavior and dietary requirements in dung flies (Scatophaga stercoraria).

Sexual behavior, Models, Flies, Diptera

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Brood-size-dependent offspring mortality in common goldeneyes reconsidered: fact or artifact?

Article Abstract:

A study of three populations of common goldeneyes (Bucephala clangula) in Finland was conducted to determine if there is a link between brood size and offspring mortality in precocial bird species with self-feeding young. The results show that offspring mortality is not related to brood size in common goldeneye. The results of past studies showing a connection between brood size and offspring mortality are probably methodological artifacts.

Research, Birds, Nestlings

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