Polymorphism in the sperm ultrastructure among four species of lizards in the genus Tupinambis (Squamata: Teiidae)
Tavares-Bastos, L., Teixeira, R. D., Colli, G. R.andBáo, S. N. 2002. Polymorphism in the sperm ultrastructure among four species of lizards in the genus Tupinambis (Squamata, Teiidae). —Acta Zoologica (Stockholm) 83: 297–307
We describe, for the first time, the ultrastructure of the spermatozoa of four species of the genus Tupinambis (Squamata, Teiidae). We identified seven polymorphic characters within this genus: the presence and shape of the perforatorial base plate, the presence of the epinuclear lucent zone, the presence of a unilateral ridge in the acrosome, the presence of a central density within the proximal centriole, the number of mitochondria and dense-bodies sets, and the shape of mitochondria. We analysed the evolution of the seven polymorphic characters by mapping them onto a current phylogeny of the species of Tupinambis, using the teiids Ameiva ameiva and Cnemidophorus sexlineatus as outgroups. Our results indicate that sperm ultrastucture characters, although of great value for phylogeny at higher taxonomic levels in reptiles and other groups, are poor predictors of phylogeny when considering the species of Tupinambis studied here. We failed to identify evidences that homoplasy in sperm ultrastructure among the species of Tupinambis is due to convergent adaptation, suggesting that the polymorphism may be selectively neutral in this group.