Anolis cristatellus. Photo by Janson Jones.
If you ever come to Puerto Rico, the first thing you’ll probably notice is the warmth. Yet, for an anole, things are not that simple. Different habitats can have different thermal regimes that potentially influence the lizard’s biology and natural history in different ways. What might be a hot and humid urban park for us can be a heterogeneous thermal landscape for a small lizard.
This is the case for Anolis cristatellus, a lizard common in most parts of Puerto Rico. Back in the early70’s, Ray Huey (1974) studied how habitat influenced this anole’s thermal biology. He found that in open and sunny habitats, this lizard actively thermoregulates and has relatively high and stable body temperatures, but that in shaded forests it is a thermoconformer and has relatively low and variable body temperatures.
Also back in the early ’70s, George Gorman and Paul Licht (1974) found that altitudinal and seasonal variation in temperature had major effects on reproductive cycles of Puerto Rican anoles. So, do reproductive cycles differ between lizards living in thermally distinct — but contiguous — habitats? Ray Huey, George Gorman and I teamed up to find out, and you can find the answer in our recent paper just published in The American Naturalist.
We studied seasonal reproductive cycles of this lizard in two localities in lowland Puerto Rico. Both localities have contiguous but thermally distinctive habitats: open parks and forests, separated by only a few meters. We caught female lizards every month for more than two years and palpated their bellies to establish reproductive condition. At both localities, lizards living in open habitats were more often gravid than were those in the forest. This difference was especially marked during winter months (of course… in a tropical sense). During these cooler months, more than 20% of open lizards were gravid, while essentially none of the forests ones were.
Large-scale geographic variation in reproductive cycles has been described in many taxa, but this is one of the few examples on a micro-geographic scale. Very likely these difference will have significant effects on the population ecology of the species, and these will be reported on soon. But in the meantime, we can say that at least for the reproductive output of Anolis cristatellus, a few meters matter!
James Stroud
Great study Luisa! Congratulations on the publication, these are really interesting results.
How much movement of individual females between the two habitat types did you observe? And if there was any, was it seasonal/periodic?
Luisa Otero
Thank you James.
We did mark and recapture at smaller patches at one of these localities, and less than 8% of the recaptured lizards showed movement between the two types of habitats without any apparent seasonality. Interestingly, most of the ones that moved were females
James Stroud
Interesting! Do you think if you moved individual females you would see a switch in their reproductive behaviour? In other words, if you moved a female from shaded forest to open trees would they quickly respond by increasing egg production, or do you think reproductive output would be conserved?
Luisa Otero
My guess is that their reproductive condition would switch according to the ‘new’ habitat where they are moved. This is something It would be very interesting to look at.
James Stroud
Very cool, thank you for your reply Luisa. Good luck with your other research – I look forward to reading all about it!