Post-copulatory mate guarding in the field cricket, Gryllus veletis:

tests of the spermatophore retention and rival male exclusion hypotheses

This is work performed by Chad Johnson , Tracie Ivy, and Jon Calos under the guidance of our advisor Scott Sakaluk. Much debate exists over why some mating systems are characterized by post-insemination associations, while in other species males and females part ways immediately after copulation. Cricket mating systems are especially interesting in this respect because the male transfers an externally-attached spermatophore to the female which gradually empties sperm into the female's genital tract after copulation has ceased. We tested two hypotheses for the adaptive significance of post-copulatory mate guarding in the field cricket (Gryllus veletis). The spermatophore-retention hypothesis, which asserts that males guard their mates in order to ensure that the female does not remove the externally-attached spermatophore before it is entirely drained of sperm, was tested by contrasting spermatophore retention times for guarded females and unguarded females. In contrast, the rival male exclusion hypothesis posits that mate guarding deters females from mating with rival males. This hypothesis was tested by comparing the remounting and remating behaviors of guarded and unguarded females in the presence of a rival male. No differences were found between guarded and unguarded females in either experiment leading us to reject both hypotheses as adaptive explanations for the evolution of mate guarding in this species.

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