A comparative study of reproduction in two populations of the lizard, anolis carolinensis

This study of Anolis carolinensis assessed genetic variation between a Tennessee population and other mainland populations, and compared reproductive variability between the Tennessee population and the extensively studied Louisiana population. A comparison of reproductive strategies between these populations revealed adaptations this species has made while invading increasingly seasonal, temperate environments.

The genetic similarity and genie heterozygosity of seven mainland Anolis populations (Tellico, TN; Birmingham, AL; Auburn, AL; New Orleans, LA; San Marcos, TX; Gainesville, FL; Naples, PL) were compared. Results for overall genetic similarity were within the range found in other studies on interpopulation heterogeneity in lizards. Four populations (Birmingham, Auburn, Tellico, Gainesville) were similar, suggesting recent common derivation; least similar populations were New Orleans and Naples with Naples the most distinct. The peripheral populations, San Marcos and Tellico, had the lowest proportion of heterozygous loci.

Geographic variation in seasonal reproductive cycles was found between Louisiana and Tennessee populations. Both sexes of Tennessee anoles had larger gonads throughout most of the annual cycle. Tennessee males showed advanced spermatogenesis for five of twelve months. Hormone levels in Tennessee anoles peaked during February and March prior to maximal spermiogenesis in males and prior to the onset vitellogenesis in females. In Tennessee and Louisiana, testicular recrudescence was correlated with temperature and testicular regression with photoperiod; however, photoperiod also was correlated with recrudescence in Tennessee anoles. Large females from both populations had a higher incidence of two oviductal eggs; however, in Tennessee the presence of two oviductal eggs also was related to the amount of precipitation. Oviposited egg weights and reproductive effort estimates differ significantly between populations.

The Tennessee population may be responding to local climatic conditions by showing more K-selected traits than Louisiana anoles. Tennessee anoles were larger as adults and as hatchlings, had larger eggs, and higher reproductive effort.