Characterizing the Annual Reproductive Cycles of Captive Male Veiled Chameleons (Chamaeleo calyptratus) and Panther Chameleons (Furcifer pardalis)

Abstract

Chameleons represent one of the most endangered groups of lizards, with most being characterized as threatened or near-threatened. Anthropogenic impacts on their native habitat are responsible for their declines. To protect these animals, we must develop functional assisted reproductive programs. However, a full understanding of their basic reproductive biology is required to develop such a program. This study represents the first attempt at characterizing the reproductive cycles of male chameleons. Sixteen veiled chameleons (Chamaeleo calyptratus) and 16 panther chameleons (Furcifer pardalis) being housed in captivity under static conditions were used for this study. Chameleons were anesthetized twice monthly for semen collection via electroejaculation, blood sampling to measure plasma testosterone concentrations, and ultrasonographic testicular measurements. Plasma testosterone concentrations were found to be significantly different between species (P = 0.02) and the interaction of species and month (P = 0.04). In veiled chameleons, plasma testosterone concentrations were significantly elevated during October through December, while for panther chameleons, plasma testosterone concentrations were elevated in July through September, and December. Electroejaculation success was found to be seasonal in both species. In veiled chameleons, semen collection was highest in April, May, and June, while in panther chameleons semen collection success was highest in March, April, May, and June. Median spermatozoa concentrations for veiled and panther chameleons were 6.66 and 7.52 x 107 million sperm/mL, respectively. Motility was lower than expected for both veiled chameleon (median 23%) and panther chameleons (median 25%). Spermatozoa clumping was a common finding. The majority of the spermatozoa (mean 51%) were...