Sperm competition within a dominance hierarchy: investment in social status vs. investment in ejaculates

V. Tamara Montrose, W. Edwin Harris, A. J. Moore, P. J. Moore

Research output: Contribution to journalJournal Article

23 Citations (Scopus)

Abstract

There is increasing recognition that male–male competition can take many forms, but as yet the form is not predictable a priori. Many recent studies have focused attention on how males in disadvantaged mating roles compensate through sperm competition. However, mating systems in which subordinate males are reproductively suppressed, particularly through the stress of social interactions, may limit the ability of males to respond by increasing investment in sperm quality. We examined the interaction between social status and ejaculate tactics in Nauphoeta cinerea, a cockroach that has a mating system with well-characterized dominance hierarchies. Both social experience with other males and social status influenced aspects of ejaculates. The stress of social interactions reduced the size of the ejaculate and number of sperm inseminated. In ejaculates formed prior to social experience, however, males that go on to become dominant inseminated more sperm than males that go on to become subordinate, suggesting innate differences among males. Our results show that though selection for increased success in sperm competition for subordinate males in a hierarchy can occur, both the traits and the way in which the balance between pre- and post-copulatory strategies is negotiated will depend on specific details of the mating system. These details will include how the physiological effects of social interactions may limit selection through male–male competition.
Original languageEnglish
Pages (from-to)1290-1296
Number of pages6
JournalEvolutionary Biology
Volume21
Issue number5
DOIs
Publication statusPublished - 8 Jul 2008

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