Sperm Competition in Birds: Evolutionary Causes and Consequences

Why should females copulate with more than one male? This is a question that Darwin did not even consider since he mistakenly (or naively) believed that females were strictly monogamous. As it turns out the females of many animal regularly copulate with several males, with the result that the sperm from different males compete to fertilize their eggs. Males also seek copulations outside their pair bond and the recent discovery that extra-pair matings can result in extra-pair paternity will force behavioral ecologists to re-evaluate the way in which they measure reproductive success. Birds are among the best known animal groups, and have proved to be ideal for investigating several different aspects of sperm competition. Tim Birkhead and Anders Moller have worked together on sperm competition in a range of bird species over a number of years and have produced this comprehensive summary of this rapidly developing area of behavioral ecology. Sperm Competition in Birds covers both functional and causal aspects of the subject and discusses the importance of sperm competition in different avian mating systems, the relationship between sperm competition and male and female reproductive anatomy and physiology, copulation patterens, paternity guards, the costs and benefits of copulating with multiple partners for both males and females, the relationship between multiple mating and paternity and finally, the far-reaching evolutionary consequences of sperm competition. Sperm competition is a central part of sexual selection and will therefore be of interest to all behavioural ecologists since the topics discussed include many that are applicable to other animal groups. The text is supported by numerous photograhs, diagrams and tables and outstanding illustrations by David Quinn.Birkhead, Tim R. is the author of 'Sperm Competition in Birds: Evolutionary Causes and Consequences', published 1992 under ISBN 9780121005412 and ISBN 0121005410.