The Female Perspective

A variety of female traits can bias paternity, including the premature interruption of copulation and the acceptance or rejection of matings from additional males. Females may also accept a male for copulation but reject him as a father. This is possible because insemination and fertilization are uncoupled in space and time (Eberhard, 1985), and because females have many opportunities to modify the probability that a given copulation will result in egg fertilization. There are at least 20 different mechanisms that can result in cryptic female choice (Eberhard, 1994, 1996), many of which may apply to cockroaches. These include sperm transport to storage sites, sperm nourishment during storage, the ability to discharge or digest stored sperm, and the biased use of stored sperm to effect fertilization, particularly in females with multiple spermathecae. Sperm selection may even occur at the site of fertilization; Eberhard (1996) gives as an example Peri-planeta, which has up to 100 micropyles for sperm entry at one end of the egg (Davey, 1965). After fertilization ovoviviparous females may abort the egg case. The multiplicity of female mechanisms reduces the likelihood that males will be able to evolve overall control of female reproductive processes, even if males try to prevent further matings via genital plugs, mate guarding, or induced unreceptivity (Eberhard, 1996). While there are no available studies that directly address cryptic choice in female cockroaches, we do have anatomical data from the taxo-nomic literature from which we can make some inferences. Here we summarize some of the relevant information in the hope that it may serve as a springboard for future investigation.

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