The effect of temperature on sperm dynamic parameters in ectotherms in general, and reptiles in particular, remains poorly understood due to the lack of consistent evidence. As a group, snakes show considerable variability regarding mating systems, male reproductive behavior, thermoregulatory behavior, and preferred temperatures. Additionally, snakes present significant variability in sperm competition levels, which is determined by the species mating system. Because sperm longevity, motility, and velocity are positively related to reproductive success in both competitive and noncompetitive conditions, the sperm physiology of ectothermic organisms may functional optimally at ecologically relevant temperatures. The objective of this work was to analyze the effect of an ecologically plausible range of temperatures on sperm dynamic parameters of two species of snakes with contrasting mating systems and sperm competition levels: Boa constrictor occidentalis and Waglerophis merremii. To accomplish this, an in vitro incubation approach was used: sperm dynamic parameters (i.e., motility and velocity) were measured on sperm solution aliquots incubated at 25°C, 30°C, and 37°C for up to 10 h by means of a phase contrast video microscopy system. Results suggested that although an increase in temperature has a general negative impact on sperm motility and velocity, the two species studied present different degrees of sensitivity to high incubation temperatures. Moreover, these differences can be explained by the dissimilar thermal conditions that the sperm of the two species would experience during their reproductive seasons, which are a consequence of the differences in their reproductive behavior. In conclusion, sperm motility and swimming velocity respond mainly to environmental conditions imposed by mating systems rather than to selection by sperm competition.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 67 • No. 1