Thursday, August 4, 2016

New, cryptic tegu species in the Neotropics

(This is mostly a summary of the introduction of the paper. The rest of the paper involves a lot of phylogenetics and how we KNOW the new species are different. I'll link to the paper if you want to read the whole thing.)

Tegus are large lizards of the Neotropics and are incredibly important to both the people and the ecosystems of the places they reside in. In ecosystems, they are predators, scavengers, and in some cases, spread the seeds of plants. For the people, they're an important source of food and income, being exported for the worldwide pet trade and in some cases hunted for skins and meat by indigenous and native peoples. Tegus and products derived from them make up 1-5% of the biological items harvested by the populations. Although the indigenous peoples' harvest seems modest, the numbers of tegus in trade suggest that huge numbers are being exported and traded. Between 1977 and 2006, 34 million tegus were traded. Tegu lizards are habitat generalists, meaning they can live almost anywhere. This is one reason why they're such a successful invasive species in Florida. In their native range, they can live in forests, savannas, trees, burrows, mangroves, and human-modified habitats like cities and farmland. Their populations must be large and stable, given that millions of tegus are traded every year and wild populations remain substantial. Tegus are classified as Least Concern due to wide distribution and abundance, and a lack of evidence that populations might be declining. However, one species of tegu, known as Tupinambis teguixin, is actually multiple cryptic species some of which live in the same locations. Cryptic species are species that are genetically different, but are indistinguishable to the human eye. Their populations have been historically and currently classified as the same species. The phenomenon of cryptic species is well known and well documented via detailed studies involving morphology, genetics, and ecology. Therefore, it seems perfectly reasonable that there would be cryptic species of tegu we didn't know about. Except for one little issue. Tegus are extensively used by humans and have been the subjects of hundreds of detailed studies, so you'd think that any cryptic species would have been discovered by now. With the splitting and discovery of cryptic species, the genus Tupinambis currently contains four species, T. longilineus, T. palustris, T. quadrilineatus, and T. teguixin. T. palustris is currently poorly known and researchers are looking into how it relates to the other species in the group. Tupinambis species are found in Columbia, northern Venezuela, the Guianas, Amazonia, and eastern Bolivia, as well as the islands Isla de Margarita, Trinidad, and Tobago. Three of four species, namely T. palustris, T. longilineus, and T. quadrilineatus, have poorly understood ranges and distributions centered in Brazil. T. longilineus has so far only been found in tropical rainforest along rivers and disturbed areas. T. palustris seems to be restricted to wetlands in Sao Paulo, Brazil, with T. quadrilineatus seeming to be endemic to the savannas of central Brazil, although it has been suggested that it might also occur in Bolivia. All three species have been described and documented since 1995. T. teguixin's range is thought to overlap the ranges of all three other species in the genus, and its range might constitute that of the entire genus. T. teguixin has a maximum body length of approximately 17 inches or 400 millimeters, making it one of the largest terrestrial Neotropic lizards. Not much is known about its genetics, making the cryptic species issue even more complicated. It has been used in hundreds of ecological, morphological, physiological, and phylogenetic studies due to the fact that it's common in museum collections and the pet trade, as well as being abundant in the wild and fairly large, but not large enough to take off your finger unless it gets really mad. In the pet trade, it's usually known as the golden tegu or black and white tegu, suggesting differences in coloration. Tegus as a whole seem to be becoming more popular in the pet trade, because when properly tamed and introduced to people, they can be incredibly docile and intelligent, like a scaly dog. Figure, 2 years ago at Repticon in Memphis/Southaven, there were no tegus at all. This year, there were 3 breeders selling them.

Images

Six images of Tupinambis species from the original paper.
A student from the Memphis College of Art walking his pet tegu in the park. Various Team My Little Python members are watching.
Buddy. When a friend of mine's family was going to Reno, they got to housesit (and tegusit) for a UNR herpetologist on sabbatical. Buddy is an incredibly tame male red tegu who goes for walks in the yard and lets himself back in, will happily sniff your feet, and basically acts like a quiet, scaly dog.

Citation: Murphy JC, Jowers MJ, Lehtinen RM,
Charles SP, Colli GR, Peres AK, Jr, et al. (2016)
Cryptic, Sympatric Diversity in Tegu Lizards of the
Tupinambis teguixin Group (Squamata, Sauria,
Teiidae) and the Description of Three New Species.
PLoS ONE 11(8): e0158542. doi:10.1371/journal.
pone.0158542

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