A história evolutiva de uma perereca Sul-Americana Scinax squalirostris (Lutz, 1925) (Anura, Hylidae): um resgate do passado e consequências futuras

• Autor(a) principal: Jardim, Tatianne Piza Ferrari Abreu
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/9067
• topic: Conservação; Delimitação; Diversidade genética; Simulação coalescente; Filogeografia; Mudança climática; Coalescent simulations; Conservation; Climate change; Delimitation; Genetic diversity; Phylogeography; GENETICA::GENETICA MOLECULAR E DE MICROORGANISMOS

Geological events of the Neogene and the climatic fluctuations of the Quaternary played an important role in shaping the landscape and climate of South America therefore directly influencing the evolutionary history of the organisms of this area over the last million years. These changes led to the alternation between warm and humid, cold and dry periods. Such alternation dictated the dynamics of retraction and expansion of open and forest landscapes. Species associated to these environments evolved following this dynamic, which lead to alteration in genetic conformation, lineage differentiation and even speciation. As in the past, future changes inclimate can modify the landscape causing changes in the geographical distribution of species. In addition, predicted global warming may lead to a decline in genetic diversity as well as lead to extinction due to species' low ability to adapt to drastic and quick changes. In this thesis two regions of mitochondrial DNA (Cytb and 12S) and one nuclear (RAG-1) were used together with coalescing simulations, and ecological niche modelling to access the evolutionary history of a Scinax squalirostris (Lutz, 1925), a species associated to the South American grasslands. In the first chapter, we sought to understand how Neogene and Quaternary geological or climatic events, respectively, may have shaped the current disjunct distribution and the genetic diversity pattern of S. squalirostris. The populations of S. squalirostris were found to have high genetic diversity, with no sign of current gene flow, a high genetic differentiation, and a stable demographic history over time with scattered origin in southern Brazil. Coalescence events date from Pliocene-Pleistocene, with haplotype sharing among geographically distant populations, which indicates incomplete lineage sorting. The paleodistribution models suggests that S. squalirostris lineages were widely distributed during the last glacial maximum (LGM) but afterwards contracting and changing their area of occurrence. These results indicate that the current geographic distribution and genetic diversity of S. squalirostris is due to the contraction of an area widely distributed in the past, generated by the dynamics of retraction of grasslands in warmer periods due to the loss of areas suitable for their occurrence. In the second chapter, we tested the hypothesis that the current populations of S. squalirostris could represent distinct lineages with candidate species not previously described, due to the current disjunct distribution. Using molecular and morphometric data the formation of two groups was rescued. One of them consists in a candidate species to be described, which is a lineage restricted to the Central-West region of Brazil. The other one comprises of populations from the South and Southeast Brazil, Paraguay, Uruguay and Argentina. In the third chapter, ecological niche modelling, molecular techniques and simulations of genetic groups were used to verify how future climate changes could alter the genetic diversity and distribution of S. squalirostris. Through two climatic scenarios with different temperature changes to 2100 (scenario 4.5 RCP increases 1.8 ° C and stabilizes, and scenario 8.5 increases 3.7 ° C and continues to increase), ecological niche modelling analysis indicated a decrease of suitable areas in the Central-West and Southeast regions, with a displacement towards the South of Brazil entering the central region of Argentina towards more anthropized areas. Most of the Central West and Northern Southeast populations may be extinct due to the absence of climatic suitable areas for their occurrence and low genetic diversity. In addition, it was observed that Protections Areas (PAs) currently harbors a large part of the genetic diversity of S. squalirostris. Thus, PAs in areas that will be ideal for the occurrence of S. squalirostris will be able to maintain their high levels of genetic diversity, but with losses of genetic diversity in the Midwest and Southeast regions. This work indicates that future climate changes will negatively affect this species, since the appropriate areas for its occurrence will be reduced and displaced. The loss and changes in genetic clusters may lead to a possible loss of the evolutionary potential of S. squalirostris populations in responding to future climate changes, which could result in the extinction of some populations.