| No evidence for sperm priming responses under varying sperm competition risk or intensity in guppies. | |
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MedLine Citation:
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PMID: 19308348 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Sperm competition theory predicts that males should tailor their investment in ejaculates according to the number of rival males competing to fertilize a female's eggs. Research spanning several taxa supports this prediction by showing that males are often sensitive to the level of sperm competition and adjust their investment in sperm numbers accordingly. More recent work has revealed that males may also tailor the quality of sperm according to the number of males competing for fertilization. Here I test for both effects in guppies (Poecilia reticulata) in an experiment that simultaneously evaluates the risk and intensity models of sperm competition. The experiment determined whether male guppies adjust the number (stripped ejaculate size) and quality (sperm velocity and viability) of sperm that are primed over a 3-day period according to experimental changes in the perceived level of sperm competition. A total of 136 focal males were initially stripped of all retrievable sperm and assayed for these sperm traits before being allocated at random to one of four treatments simulating different levels of sperm competition risk and intensity. During the 3-day treatment phase, focal males had visual and olfactory access to a sexually receptive (initially virgin) female maintained with different numbers of stimulus males to simulate variation in the risk and intensity of sperm competition. Following this, males were assayed again for the sperm traits. Contrary to predictions, there was no significant change in any of the measured variables among treatments, although qualitatively the patterns for sperm velocity and viability did conform to expectation. The lack of any trend for the number of sperm primed was unequivocal and future work examining the effects of sperm competition on sperm production should focus on whether males differentially allocate sperm numbers among matings that differ in the level of sperm competition. |
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Authors:
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Jonathan P Evans |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2009-03-24 |
Journal Detail:
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Title: Die Naturwissenschaften Volume: 96 ISSN: 1432-1904 ISO Abbreviation: Naturwissenschaften Publication Date: 2009 Jul |
Date Detail:
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Created Date: 2009-07-06 Completed Date: 2009-10-23 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0400767 Medline TA: Naturwissenschaften Country: Germany |
Other Details:
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Languages: eng Pagination: 771-9 Citation Subset: IM |
Affiliation:
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Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Nedlands, Perth, 6009, WA, Australia. jonevans@cyllene.uwa.edu.au |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Body Size Cell Survival Competitive Behavior Ejaculation / physiology Female Male Poecilia / physiology* Probability Risk-Taking Sperm Count Spermatozoa / cytology, physiology* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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