The Reproductive Cycle Of The Brown Anole In Taiwan

Brown anoles mating.

Most invasive vertebrates have a high reproductive rate, and are able to build up a large population under ideal conditions. A recently published report on the reproductive cycle of the brown anole (Anolis sagrei) in Taiwan highlights this again.

This study demonstrated that the reproductive cycle of the Anolis sagrei population in Taiwan is long and cyclic, and that it is very similar to that of conspecific populations in Belize, Cuba, Florida, and Hawaii.

We found that as in Florida, the females become sexually mature at about 34 mm SVL. As in other studies, we found that Anolis sagrei females produces multiple clutches, consisting of a single egg, throughout most of the year, and that due to sperm storage, are able to produce viable eggs for a few weeks, even in the absence of males.

Unlike in other studies, we found that the males could be sexually mature at a much smaller SVL (ca. 30 mm), and that at least some males with spermatozoa, which could mate, are present throughout the year. The smaller SVL of the males mean a shorter time from hatching to the age at which mating can commence. And even though it is uncertain that such males would be able to compete with larger territorial males, these smaller males would certainly have mating opportunities in the absence of larger males in founder populations.

We found that the hatchlings have a SVL of about 18 mm, and as in other studies, they hatch after a period of about 30 days.

In view of the potential for A. sagrei taking over new territories, to prevent future introductions of this species, we strongly feel that drastic steps are merited.