Reproductive Biology of Four Species of Tropical Australian Lizards and Comments on the Factors Regulating Lizard Reproductive Cycles

Abstract

We examined the reproductive cycles of four species of lizards through one year in the middle-latitude (19?S) seasonal Australian tropics. The gonads of male Cryptoblepharus virgatus were active all year except during mid-summer (January-March), while female gonads were active August through January. The reproductive condition of male Carlia pectoralis peaked during September through November, while female condition peaked in November through February. Male Heteronotia binoei reached peak reproductive condition in July-September, but appeared to be capable of reproduction in April through November. Female gonadal activity in H. binoei commenced in July, and continued through January. Lampropholis delicata males were in reproductive condition in all months, while females were reproductive September-February. Female reproductive activity in all species except C. pectoralis com- menced earlier in the year than in related species at higher latitudes. Because female reproductive activity in two of the species commenced in mid-winter, which is also the middle of the dry season, we do not believe that it is triggered by increasing temperature, photoperiod, or rainfall. Instead, reproductive activity may be controlled by total exposure to solar radiation, either across the spectrum or concentrated in the ultraviolet.