Anolis lizards have long been thought to be territorially polygynous reptiles, meaning specifically that males maintain and defend a small area in which they sire all (or the vast majority) of the offspring produced by females residing in said area. Ambika Kamath (UCSB) challenged that long held belief today in her presentation at this year’s Evolution meeting.
A conventional model of territoriality: a male defends a territory containing multiple females (from https://ambikamath.wordpress.com/, photos by Rachel Moon)
When Ambika looked at the historical basis of the initial assertion that anoles are territorial she found that this claim was made with little to no empirical evidence and that there are several studies documenting females residing within a male’s territory producing offspring sired by multiple males. This made her wonder if the species she works on (Anolis sagrei) are, in fact, territorially polygynous. She did so with an extensive empirical study of 253 lizards over an area of 7100m2. Her results clearly indicate that male A. sagrei do not maintain the assumed small territory, rather, they regularly travel outside of their projected 10m diameter range throughout the breeding season (photo below). Additionally, the majority of females in the study both encounter and produce offspring sired by multiple males.
Dark circles = static territory, small circles = observed sightings of A. sagrei males over the breeding season
Ambika concludes that A. sagrei does not fit the definition of a territorially polygynous species. Males do not maintain the expected territories and there is significant polyandry. Importantly, Ambika points out that the assumption of territoriality influences study design by limiting sampling area and duration and that such limitations simply reinforce the territoriality assumption. Her findings call for the potential re-tooling of study designs and empirical investigation into the mating systems of other species long considered territorially polygynous.
For more on this research, check out the recent publication on this work:
Kamath A, and JB Losos. 2017. The erratic and contingent progression of research on territoriality in Anolis lizards. Behavioral Ecology and Sociobiology 71:89.
John Rubin
In unscientific observations of sagrei in my backyard, the male doesn’t defend a territory. He establishes himself on a perch (the higher the better) and the females find him. In fairly rapid succession if it’s a great perch, like the arm of a lawn chair.