Female Sticklebacks Prefer To Spawn With Males Whose Nests Contain Eggs

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Abstract
Does the presence of absence of eggs in a male stickleback's nest affect the chance that a female will spawn with him? Female threespined sticklebacks (Gasterosteus aculeatus) were presented alternatively to males with or to males without eggs. Our results show that the chance that a female will follow a male to his nest is unaffected by whether he has eggs. Once a female has reached the nest, she can either enter it and spawn, or back out and refuse. There was a tendency for females to be more likely to spawn than to refuse if the nest contained eggs. In a sequential choice experiment females that had refused a male without eggs were then presented to a second male, either with eggs or, as a control, without eggs. Females were significantly more likely to spawn with the second male if he possessed eggs. The finding that females prefer to spawn with males with eggs suggests functional explanations for female refusal, male egg kidnapping, and male 'displacement fanning'. Does the presence of absence of eggs in a male stickleback's nest affect the chance that a female will spawn with him? Female threespined sticklebacks (Gasterosteus aculeatus) were presented alternatively to males with or to males without eggs. Our results show that the chance that a female will follow a male to his nest is unaffected by whether he has eggs. Once a female has reached the nest, she can either enter it and spawn, or back out and refuse. There was a tendency for females to be more likely to spawn than to refuse if the nest contained eggs. In a sequential choice experiment females that had refused a male without eggs were then presented to a second male, either with eggs or, as a control, without eggs. Females were significantly more likely to spawn with the second male if he possessed eggs. The finding that females prefer to spawn with males with eggs suggests functional explanations for female refusal, male egg kidnapping, and male 'displacement fanning'.