Male and Female Reproductive Cycles of the Jamaican Lizard, Anolis opalinus

Abstract

A montane population (elev. 690 m) of the Jamaican lizard, Anolis opalinus, was monitored weekly for 12 months. A greater percentage of reproductive individuals was found year-round than in any previously described anole from a similar latitude and elevation. The high level of annual reproduction occurred in spite of distinct wet-dry periods (171 cm of rain, May-Oct.; and 32 cm of rain, Nov.-April). All males (n = 146) from all months were fully gametogenic. Morphometrics of sexual structures, however, reflected some monthly variance. Mean monthly testis weight showed a 2.2-fold annual range; other measured sex structures fluctuated much less (0.3-0.6-fold). As a group, measured variables reached their maxima during April-July and minima during Oct.-Nov. The testicular cycle was shifted two months in advance of the wet season, with almost no male reproductive structures correlated with the annual cycle of climatic variables. Males showed no tendency to lose weight during their peak reproductive months. Field observations recorded copulations, advertisement displaying, and territorial defense the year-round. For all females (n = 173), the proportion gravid in monthly samples varied from 42% in Dec. to 100% in Aug. Though apparently not initiated by the onset of rain in May, reproductive variables combined to reach their maxima (JuneOct.) during warm wet months. Occurrence of females carrying two oviductal eggs began in April and ceased in Oct.; total oviductal egg volume overlapped the seven months of highest maximum daily temperatures (April-Oct.) and the six months of greatest rainfall (May-Oct.). Large oviductal egg size was associated with large females, but larger females did not appear to produce more eggs than smaller females in either the wet or dry periods. Female reproductive variables reached their greatest levels several months after the male cycle had registered its maxima; no reproductive variables significantly covaried between the sexes.