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1 April 2009 Sperm Viability in the Reproductive Tract of Females in a Population of Sceloporus mucronatus Exhibiting Asynchronous Reproduction
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Abstract

Asynchronous reproduction is a common phenomenon in high-elevation populations of lizards from Central México. Sperm storage in the reproductive tract of females is the mechanism for making oocyte fertilization possible. Our study addresses questions related to functional oviductal sperm storage of females mating on different dates throughout the reproductive season. A population of Sceloporus mucronatus with copulation in the summer and ovulation in the fall was chosen for this experiment. Eleven females that copulated in the field during June and 13 females that copulated in captivity during August were maintained in the laboratory until parturition. The number of pregnant females and the litter sizes produced in each experimental group were indicative of the viability of the stored sperm. Sperm stored in the reproductive tract of females were able to fertilize eggs after 4 months. No significant differences were found in the number of pregnant females between the 2 experimental groups nor in the litter sizes that they produced. We found that the amount of time sperm were held in the female reproductive tract (ca. 3 months) had no effect on the capacity of sperm to fertilize eggs. Histological examination of 8 oviducts collected before the mating season eliminated the possibility of sperm storage from one year to the next. In this system, sperm retention could have evolved as a response mechanism to deal with the asynchrony between sexes in the reproductive cycles. However, we cannot rule out alternative hypotheses.

© 2009
Angela M. Ortega-León, Maricela Villagrán-Santa Cruz, J. Jaime Zúñiga-Vega, Raúl Cueva-del Castillo, and Fausto R. Méndez-de la Cruz "Sperm Viability in the Reproductive Tract of Females in a Population of Sceloporus mucronatus Exhibiting Asynchronous Reproduction," Western North American Naturalist 69(1), 96-104, (1 April 2009). https://doi.org/10.3398/064.069.0121
Received: 18 March 2008; Accepted: 1 September 2008; Published: 1 April 2009
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