RESPONSE OF THE MALE REPRODUCTIVE SYSTEM OF LIZARDS (ANOLIS CAROLINENSIS) TO UNNATURAL DAY-LENGTHS IN DIFFERENT SEASONS

Abstract

The reproductive tracts of adult and immature anoles exposed to 18, 16, 14, 9, and 6-hour as well as normal day-lengths were examined histologically. The reproductive system responded to long day-lengths at all seasons. Some animals achieved full breeding condition in all experiments except those initiated in September and October. No "refractory period" was found nor was a previous exposure to short days essential for stimulating spermatogenesis. The closer to the normal breeding period aach experiment was started the more complete the response to long day-lengths. The longer the day-length the greater the response obtained, although in certain experiments an 18-hour exposure appeared to affect more individuals adversely than did a 16-hour exposure. Exposure to short day-lengths did not significantly retard the initiation of the inherent reproductive cycle in the fall and winter. However, short photoperiods caused marked involution of the gonads and accessory sex organs if experiments were started near or after the peak of spermatogenesis. Sub-adult lizards that grew significantly in length during the experiments responded as well as or better than adults. Captive lizards sacrificed between Feb. and July following 60 days'' exposure to normal day-lengths and 28[degree]C had significantly larger average testis weights than did samples of wild lizards sacrificed during these months.