Category: Jeffrey Carrier (Faculty Co-author)

Nick Whitney

Whitney, N., Pratt Jr., H. L., & Carrier, J. (2004).  Group courtship, mating behaviour, and siphon sac function in the Whitetip Reef Shark, Triaenodon obesus. Animal Behaviour, 68, 1435-1442.

Abstract: We analysed video records of three mating events involving nine free-living whitetip reef sharks in Cocos Islands, Costa Rica to examine reproductive behaviour in this species. We describe several behaviours never before documented in this species, and four behaviours never before documented in any elasmobranch. Here, we also present the first hypothesis for the function of the male’s paired reproductive organs, the siphon sacs, to be based on observations of mating sharks. We introduce terminology for three separate siphon sac structural components that are externally visible during courtship and mating in this species. Based on our analyses, as well as evidence from past mating studies, the siphon sacs in whitetip reef sharks appear to be used to propel sperm into the female’s reproductive tract, not for flushing the female’s reproductive tract of sperm from previous males. We discuss the implications of ‘group courtship’, ‘siphon isthmus constriction’, ‘reverse thrusting’, ‘postrelease gaping’ and ‘noncopulatory ejaculation’.

Andrea Lindley and Eleanora Maries

Saville, K. J., Lindley, A. M., Maries, E. G., Carrier, J. C., & Pratt Jr., H. L. (2002).  Multiple paternity in the Nurse Shark, Ginglymostoma cirratum. Environmental Biology of Fishes, 63, 347-351.

Abstract: For over a decade, we have been studying the reproductive behavior of the nurse shark, Ginglymostoma cirratum, in the Dry Torugas off the Florida Keys, an important mating and nursery ground for this species. In the course of these studies, we have used a variety of tags and tagging protocols to monitor individual animals. Here we report the use of molecular methods for the genetic analysis of nurse sharks. Specifically we have analyzed genetic variation at the MHC II alpha locus using the polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis of the amplified products. We found this technique to be a relatively rapid and reliable method for identifying genetic differences between individual sharks. Applying this method to a family of sharks consisting of a mother and 32 pups, we demonstrate that at least four fathers must have fathered this brood. Multiple paternity in the nurse shark suggests a mechanism by which populations of this species may maximize genetic variability. This seems especially valuable for philopatric species whose migratory movement, and thus potential for genetic diversity, is limited.

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