Lagartos

Investigators

Dr. Jack Sites, Brigham Young University
Dra. Mariana Morando, Central Nacional Patagónico
Dr. Luciano Avila, Central Nacional Patagónico
Dr. Pedro Victoriano, Universidad de Concepción

Phymaturus

Phymaturus es un grupo pequeño de lagartos de tamaño mediano que habitan sólo los Andes de Argentina y Chile y la meseta patagónica central. Todas las especies de Phymaturus son muy similares en la forma de su cuerpo: robusto, con patas cortas y una cola espinosa. La coloración suele ser oscura, aunque algunas especies tienen áreas de colores brillantes anaranjadas, amarillas o verdes en la cola o el cuerpo. Todas las especies conocidas son herbívoras, pero ocasionalmente pueden comer insectos. Son estrictamente saxícolas, encontrándoselas en zonas con grandes rocas y grietas rocosas. Las especies de Phymaturus son vivíparas, con una compleja organización social en “clanes”. Un caso de partenogénesis facultativa se ha informado en lagartos cautivos. Durante casi un siglo sólo se ha reconocido una única especie dentro de este género, pero desde 1973 se han descrito varias especies nuevas, alcanzando actualmente un total de 20 especies. Sin embargo, un trabajo molecular preliminar indica que varias poblaciones pueden ser nuevas especies aún no descritas.

Liolaemus

With more than 190 species, Liolaemus constitutes one of the most speciose squamate genera in the World. Most species of Liolaemus occur in southern South America, mainly in Argentina and Chile, but some species reach Bolivia, Brazil, Paraguay, Peru, and Uruguay. These lizards occupy a variety of habitats including coastal and inland sand dunes, pampas, temperate forest, and Andean-patagonian rainforest, but the majority of the species inhabit arid and semiarid environments of Andes, Patagonia, Monte desert, lowlands east and west of Andes, and some neighboring mountain chains. Latitudinal distribution of the genus span for almost 41°, from Andes close to Lima in Peru to Isla Grande de Tierra del Fuego in southern Argentina. Some species are found eating insects in the tidal algae remains meanwhile others are found in stony and windy plains of Puna, up to 5000 m. They are small to medium-sized lizards, some species are very colorful and conspicuous but others have darker and unremarkable coloration. Spots, lines, and bands are very common in the coloration of these species. The majority of the species are insectivorous, some are herbivorous, but others are omnivorous; viviparity is widely found in Liolaemus with approximately 50% of species with this reproductive mode; at least one species has been discovered with a unusual reproductive mode, parthenogenesis, probably the first case in iguanids.
Photo courtesy of Jim Schulte More than 40 species of Liolaemus have been described during the last 15 years. One of the main causes of this dramatic recent increase in the number of known species is that surveys and collections are being made in previously unexplored areas, existing collections have been carefully examined, and new methodology to determine species limits have been applied in some cases. Hence, it is very likely that a considerable number of new species will be described in the near future.

Liolaemus wiegmann

Liolaemus wiegmann, 1834, is the most common lizard genus in Chile represented by 76 species inhabiting a broad variety of ecological conditions and with a broad geographical range. This genus is represented by several endemic species within Chile, presumably a result of the isolating effects of the uplift of the Andes, effectively isolating Chilean taxa from Argentinian congeners. The high richness of species and the high intraspecific variation frequently observed in morphological features, suggest that this genus has been a dynamic group in an evolutionary sense and it has likely speciated extensively as a response to recent and ancient tectonic and climatic changes in this part of South America. However, the microevolutionary history within the genus is poorly understood. We are interested in to study co-distributed species of Liolaemus from South-Central Chile in biogeographical areas corresponding both Mediterranean, Andean, temperate forests, and Patagonean formations. These scenarios are interesting to analyze in the context of the NSF project because great part of the Chilean ecosystems can be considered like sister formations of the Argentinean Patagonia in the historic biogeographic background. Our purpose is to get a comparative study of phylogeography, to test hypotheses about evolutionary processes involved within their geographic range. We expect similar phylogeographic patterns among populations of each species because several species have been co-distributed for a long time and submitted to similar paleoclimatic and geomorphological changes. So, it is reasonable to expect a congruent evolutionary history for some of the Liolaemus species. By using mitochondrial and nuclear DNA sequences, we will recover hypotheses of evolutionary relationships of these species. Sequences will be used to implement Nested Clade Analyses(NCA). Nested clade distance measures were tested for associations with geographic locations, and an inference key then followed to derive a plausible biological cause (range expansion, fragmentation or reduced gene flow). The combined data set for all sequenced gene regions will be used for traditional phylogenetic analyses (Maximum Parsimony, Maximum Likelihood, and Bayesian), using several outgroups according the phylogenetic position of the different species. We will apply a comparative analysis too which is useful for partially co-distributed taxa how in this case, and with the advantage that it’s possible to get statistical estimations of the congruence level between the different evolutionary history of different taxa. The results are discussed with respect to the existing palaeoclimatic and palaeotectonic data from South-Central Chile.

Para más información:

Chilean Valdivian Forests
Liolaemus Tenuis, The Thin Lizard