Copulatory behaviour of the lizard Anolis sagrei: alternation of hemipenis use

The pattern of use of the hemipenes, the two independently functioning intromittent organs of squamate reptiles, was investigated in the male brown anole, Anolis sagrei. Males demonstrated a significant tendency to use the left and right hemipenes alternately when mated daily for 7 days with different females. The duration of copulation differed significantly among males and was independent of the hemipenis used. Hemipenis use was also examined in two successive copulations separated by different time intervals. After an intercopulatory interval of up to 3 h, males showed a significant tendency to alternate in the use of their hemipenes. This trend was still present following an intercopulatory interval of 24–26 h, but was not detectable following an interval of 72–74 h. Thus, alternation of hemipenis use in male brown anoles declines as the interval between copulations increases, suggesting that males adjust their copulatory posture in relation to the length of the intercopulatory interval.