PPG - Ecologia e Evolução

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Navegando PPG - Ecologia e Evolução por Orientador(es) "Alexandrino, Joao Miguel de Barros [UNIFESP]"

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    Diversidade ecológica e genética em populações de Hypsiboas puchellus (Hylidae) de dois biomas da América do Sul
    (Universidade Federal de São Paulo, 2013-11-29) Ugioni, Luiz Fernando Rocha [UNIFESP]; Alexandrino, Joao Miguel de Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Biological diversification generates patterns of genetic diversity, be it driven by neutral biogeographic (variance and dispersal) or populational (demographic fluctuation) or even adaptive processes mediated by natural selection (e.g., selection along ecological gradients). We undertook a study on the ecological and phylogeographical diversity of an amphibian widespread in the the subtropics of South America that occurs in three distinct biomes. Firstly, we used multivariate analyses to test if bioclimatic niche components of H.pulchellus indicated niche divergence or conservatism along a spatially autocorrelated ecological gradient. Secondly, we used present day species distribution models to make projections of the impact of Pleistocene climatic fluctuations (specifically, the last glacial maximum, 21K years ago) on the geographic range of H.pulchellus. Thirdly, we performed phylogenetic analyses using maximum parsimony and maximum likelihood methods to check if multiple independent lineages existed within the species H. pulchellus, and if those would be geographically associated with distinct biomes across the species range. Fourthly, we looked for biome associated geographic population structure within H.pulchellus, both with a bayesian analysis and a traditional analysis of molecular variance, respectively, without and with a priori defined groups. Fifthly, we used tests based on summary statistics to examine the hypothesis that populations of H.pulchellus of distinct biomes had distinct demographic histories. Multivariate analyses showed that the species bioclimatic niche is distinct in each biome which may suggest some degree of ecological divergence between populations in each region. The species paleodistribution projection (LGM) suggests species range stability, i.e., that Pleistocene climatic fluctuations did not drive diversification within H.pulchellus. Phylogenetic analyses of mitochondrial and nuclear DNA gene fragments did not uncover evolutionarily independ at lineages within H. pulchellus. A contrasting patterns was however apparent for mtDNA where divergente haplotypes were more commonly observed in regions of high altitude in the Atlantic forest, at Rio Grande do Sul, while most sites in lowland regions throughout the species range showed an excess of less divergent and rarer haplotypes. Analyses of molecular variance did not uncover phylogeographic structure associated with the Atlantic forest and the Pampa biomes, but bayesian inference of population structure, for both mtDNA and nDNA, consistently uncovered a geographic group of localities of the highlands of the Atlantic forest that tends to be genetically distinct from neighboring regions. Finally, one test of demographic fluctuation vs. stability (Fu’s Fs) showed that populations in the Pampa region may have experienced demographic expansion while those in the Atlantic forest may have been relatively stable.
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    Modelagem da distribuição geográfica e conservação de duas espécies ameaçadas de Rhipsalis (Cactaceae) na Mata Atlântica
    (Universidade Federal de São Paulo, 2014-04-24) Franca, Valeria Braga [UNIFESP]; Alexandrino, Joao Miguel de Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Geographic distribution models and conservation status of two endangered species of Rhipsalis (Cactaceae) in the Atlantic Forest. The Rhipsalis (Cactaceae) is the most abundant genus among all the epiphytic cactus. This group is divided into five subgenera based on morphological and physiological different features, particularly in the format of cladodes and flowers arrangement. Phyllarthrorhipsalis is the most diverse subgenus, with 13 species described in which the predominant feature is the stem flattened shape. Rhipsalis crispata (Haw.) Pfeiffer. and Rhipsalis oblonga Loefgr. are both endemic of the Atlantic Forest and are phylogenetically very close species. Initially, Rhipsalis crispimarginata Loefgr. was not covered at this work because they are not recognized as a valid species, but during this research, we have been found morphological differences that may contribute to the species segregation, thus justifying their posterior inclusion. In order to identify geographical distribution patterns and also reassess the conservation status of the three studied species, the habitat was defined based on information gathered from online data banks, herbarium exsiccates and literature. This survey resulted in 20 presence points to R. crispata, 18 to R. crispimarginata and 32 to R. oblonga. The coordinates were plotted in ArqGIS software in order to build a species distribution maps and the Maxent algorithm was used to modeling the potential species (MPE), using five bioclimatic variables that was chosen from a correlation matrix. For each species were generated models in present and future scenarios CCSM4 and MIROC5, both for the year 2070 and based on rates of carbon emissions. The models generated for the present, revealed new potential areas for species occurrence, however the most of these populations was not found in the field and possibly do not resisted to the intense anthropogenic pressure, that suffered recently, since require appropriate conditions of light and humidity to thrive. The projections for the future indicated a worse scenario, with a great habitat loss in southern Bahia State and in a band stretching from the north of São Paulo to Santa Catarina State, especially for the species R. crispimarginata. Thus, considering this vulnerability, we recommended an immediate taxonomic revision and its inclusion in endangered species list from IUCN-International Union for Conservation of Nature. After finding the reduction of their areas of occupation, we also suggest a change in the conservation state of R. oblonga of "Vulnerable" (VU) for Endangered (EN) category in Appendix II of CITES and for R. crispata, to "Critically Endangered" (CR) one.