Reproductive trait variation in the Sceloporus scalaris species group (Squamata: Phrynosomatidae) from the Transvolcanic Belt, Mexico

Abstract

Variation in life history traits can arise from both genetic and environmental factors. We investigated reproductive activity and variation in some life history traits among four lizard species [Sceloporus bicanthalis, S. subniger (viviparous), S. aeneus and S. scalaris (oviparous)] from different populations of the S. scalaris group. We consider that the phylogenetic history of the group might explain the similarities in the reproductive and life history traits. In oviparous species, reproductive activity was seasonal, as well as the viviparous S. subniger, but S. bicanthalis showed continuous breeding. Sceloporus aeneus showed the smallest snout–vent length (SVL) at sexual maturity. There were also differences in SVL and clutch/litter size among species. Clutch/litter size was positively correlated with female SVL in most species. However, egg mass/volume did not vary among species or populations. Among populations within a species, there were differences in SVL (S. aeneus), clutch size and egg volume (S. scalaris) for oviparous species. In addition, similarities in SVL (S. scalaris, S. bicanthalis), egg mass (S. scalaris) and litter size (S. bicanthalis) were found in both oviparous and viviparous species. These results showed that variation in these life history traits are due to environmental factors and the evolutionary history of the group.