Overlap of Female Reproductive Cycles Explains Shortened Interclutch Interval in a Lizard with Invariant Clutch Size (Squamata: Gekkonidae: Paroedura picta)
Abstract
Variable clutch size is unambiguously an ancestral state in rep- tiles. Only several lizard lineages have evolved so-called invari- ant clutch size, where all females lay just one or two eggs per clutch.
This mode of reproduction is characteristic for geckos. In some gecko lineages, decreased fecundity in a single clutch is compensated by conspicuous shortening of interclutch in- tervals.
The proximate mechanism of high clutch frequency in these geckos is not known. Here, we document that three sub- sequently laid clutches develop simultaneously in females of the Madagascar ground gecko (Paroedura picta).
The extremely short interclutch intervals in this species-even as short as a week-thus could be attributed to the overlap of female re- productive cycles. Such overlap should be associated with al- tered female hormonal cycles.
Based on measurements of hor- monal levels, we suggest that cycles of estradiol and progesterone during reproductive cycles of females in P. picta are largely independent. Thus, in contrast to the presumable ancestral reptile state, higher levels of progesterone do not seem to interfere with vitellogenesis in this species.
We discuss po- tential consequences of this derived mode of reproduction, such as possible simultaneous maternal transfer of nutrients and other yolk components to several subsequent clutches.