Thursday, June 30, 2011

The terms “sperm competition” and “cryptic female choice” in insect biology

In a recent Natural History article, Marlene Zuk looks from a female perspective at the reproduction of insects [1]— an area of study that some see as overloaded with male-dominated thinking and terminology.  A good example is the term “sperm competition,” which goes back to Geoffrey A. Parker at the University of Liverpool [2,3]. This phrase denotes the effort toward successful fathering in multiple mating events.

Who decides about the success and who controls of what happens in reproduction? The inseminating male or the receiving female? Different insect species, as Zuk illustrates, exhibit a zoo of  genitalia including penises with spikes, scoops, hooks, knobs, kinks, coils—you name it—to enhance sexual interaction and sperm ejaculation. But it may be the female who finally controls paternity. The defining term is “cryptic female choice,” which was coined in 1983 by Randy Thornhill at the University of New Mexico [4,5].  This phrase refers to the postcopulatory ability of females to favor one male of her species over another: this ability includes the selection of sperms from various partners, stored in different parts of her reproduction tract, before fertilizing her eggs. For example, the female moth Utetheisa ornatrix—after mating many times—selects only the sperm of males with large spermatophores for fertilization [6].

Keywords: entomology, behavioral ecology, selective reproduction, sexual selection, evolution, competition among males, post-coital activity

References and more to explore
[1] Marlene Zuk: Sperm and Eggs on Six Legs. Natural History June 2011, 119 (6), 28-35.
[2] What is Sperm Competition? [].
[3] Stuart Wigby and Tracey Chapman: Sperm competition. Magazine R100 [].
[4] Randy Thornhill, research and publications:
[5] Elia T. Ben-Ari: Choosy Females. BioScience January 2000, 50 (1), 7-12. [].
[6] Female sperm choice of the moth Utetheisa ornatrix [].

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