One of the main goals of the work we are doing this summer is to estimate the abundances of the various anole that are present at each site. To do this, we survey each plot (4-6 plots per site) 2 times a day for three days in a row. Each survey lasts a minimum of two hours, where we walk a prescribed path through the circular plot searching out every individual lizard.
Each lizard gets photographed and painted with paint. The paint allows us to record if we’ve seen a particular individual before (each survey gets a unique colour of paint) and the ratio of new to previously seen and painted lizards allows us to estimate the total population abundance. The photographs allow us to both confirm that a lizard has been painted, but more importantly, it allows us to confirm the species identity of each individual.
This latter task can be challenging. Some sites can have up to five potential different species and while some are easy to immediately distinguish via size, location in the habitat, behaviour or morphology, (eg crown-giants vs grass-bush anoles), the species complexes can be impossible to distinguish.
What is a species complex, you may ask?
Well, according to Wikipedia, a species complex is, “a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear”. They may hybridize regularly and scientists may still be sorting out where the boundaries between subspecies and species are. Using genetics to differentiate between species may help, but in the field, when we are identifying animals through binoculars without a lab, distinguishing between the species or subspecies of a species complex is a nightmare. Particularly when the species haven’t been resolved (ie boundaries between species haven’t been figured out yet) or in parts of the country where scientists rarely go so it is not known how far the species’ (which may or may not actually be resolved) range may extend.
Across the southern Dominican Republic there is a species complex of trunk-crown anoles that are all bright green (“the green ones”). There are big green ones, little green ones, green ones with electric blue tails, green ones with striped tails, and green ones with red spots behind the eye. However, it is largely unknown how much of this colour variation corresponds to different sexes, subspecies, population variation, or differences between species. Some of these green ones are high elevation specialists, some are not, and it is unknown where the elevation cut-off is.
At these sites, where the boundaries between species are blurred, identifying species will be left to a later date when the experts (ie my supervisor) can use the photos taken during surveys to cross-reference with the literature to (hopefully) disentangle the species identification.
ummm... I thought the tails were painted as field identifiers!