Filogeografia e genômica populacional de anuros neotropicais: estruturação, diversidade e demografia histórica
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Data
2019-05-31
Autores
Silva, Amanda Santiago Ferreira Lantyer
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Universidade Estadual Paulista (Unesp)
Resumo
Nesta tese exploramos a diversificação de espécies de anuros da Tribo Lophyohylini distribuídas na Mata Atlântica (MA) e Caatinga, biomas do Brasil. Para tanto, utilizamos dados genômicos e métodos de filogeografia estatística para analisá-los, uma abordagem robusta e até então ainda escassa na filogeografia dos organismos sul-americanos. Através do sequenciamento Sanger amostramos trechos de DNA mitocondrial (mtDNA) e através do sequenciamento de alto rendimento obtivemos polimorfismos de nucleotídeo único (SNPs) do DNA nuclear (nDNA). No primeiro capítulo, reunimos 82 amostras da espécie Aparasphenodon brunoi que apresenta distribuição nas terras baixas e costeiras do bioma MA, sendo considerada ideal para investigar o papel da instabilidade climática do Pleistoceno em seu processo de diversificação. Ainda no primeiro capítulo, para avaliar a influência do comportamento filopátrico, associado às diferenças no modo reprodutivo, na dispersão e consequentemente, no fluxo gênico entre populações, reunimos 72 amostras de A. arapapa e A. aff. brunoi. Estas tratam-se de espécies simpátricas, de distribuição mais restrita e com modos reprodutivos contrastantes o que as tornam ideais para esse tipo de comparação. De acordo com a inferência baseada em modelos demográficos, por volta do último máximo glacial (UMG) a população norte de A. brunoi se manteve estável enquanto que a do sul experimentou um gargalo seguido de expansão recente. Além disso, a população norte de A. brunoi apresenta maior diversidade nuclear do que a população sul. A paleomodelagem de distribuição de A. brunoi corrobora o padrão disjunto das populações norte e sul assim como a distribuição relictual da espécie no UMG quando desconsiderada a plataforma continental como área de expansão da MA. Dessa forma, sugerimos que a diversificação em A. brunoi está em consonância com a hipótese de refúgios pleistocênicos para a MA. Quanto ao segundo aspecto estudado no primeiro capítulo, detectamos similaridade no padrão de diversidade e endogamia para A. arapapa e A. aff. brunoi, contradizendo nossas expectativas. Sugerimos que o comportamento filopátrico dos machos de A. arapapa não deve atuar fortemente em limitar a dispersão da espécie. No segundo capítulo, reunimos 69 amostras de C. greeningi para investigar sua diversificação intraespecífica (distribuído na Caatinga) e comparar sua demografia histórica com a de A. brunoi, considerando que as espécies se encontram em biomas distintos e adjacentes teriam experimentado expansões e contrações de forma antagônica. Corythomantis greeningi apresentou fraca estruturação geográfica para o gene mitocondrial ND2 mas não para o COI. A análise do nDNA revelou a existência de duas populações, uma distribuída a leste e outra a oeste. As análises demográficas para C. greeningi indicam que a população do leste sofreu expansão tal como observado para outras espécies de anuros do bioma e a do oeste sofreu retração durante o UMG. Sugerimos que a população do oeste pode ter sido sujeita a retração devido a invasão de áreas úmidas na Caatinga antes de sua expansão. Essa dinâmica foi aproximadamente sincrônica e antagônica à retração da população de A. brunoi ao sul da MA, possivelmente refletindo a dinâmica geográfica antagônica dos biomas Caatinga e MA no UMG. A história evolutiva dos organismos aqui estudados sugere, de modo geral, que o passado dos biomas em que se inserem é complexo e sua história é complementar.
In this dissertation we explored the diversification of anuran species of the Lophyohylini Tribe distributed in the Atlantic Forest (AF) and Caatinga biomes of Brazil. To do so, we used genomic data and methods of statistical phylogeography to analyze them, a robust and until then still scarce approach in the phylogeography of South American organisms. Through the Sanger sequencing we sampled mitochondrial DNA (mtDNA) and through high-throughput sequencing we obtained single nucleotide polymorphisms (SNPs) from nuclear DNA (nDNA). In the first chapter, we collected 82 samples of the species Aparasphenodon brunoi that is distributed in the low and coastal lands of the AF biome, being considered ideal to investigate the role of Pleistocene climatic instability in its diversification process. In the first chapter, to evaluate the influence of philopatric behavior, associated with differences in reproductive mode, dispersion and consequent gene flow among populations, we also collected 72 samples of A. arapapa and A. aff. brunoi species. These are sympatric species with a narrower distribution and with contrasting reproductive modes, making them ideal for this type of comparison. According to the inference based on demographic models, around the last glacial maximum (LGM) the northern population of A. brunoi remained stable while the southern one experienced a bottleneck followed by recent expansion. In addition, the northern population of A. brunoi exhibits greater nuclear diversity than the southern population. The paleomodeling distribution of A. brunoi corroborates the disjoint pattern of the northern and southern populations as well as the relictual distribution of the species in the LGM when the continental shelf is not considered as an area of expansion of the AF. Thus, we suggest that the diversification in A. brunoi is in line with the hypothesis of Pleistocene refuges for AF. As for the second aspect studied in the first chapter, we detected similarity in the pattern of diversity and inbreeding for A. arapapa and A. aff. brunoi, contradicting our expectations. We suggest that the philopatric behavior of A. arapapa males should not act strongly in limiting the dispersion of the species. In the second chapter, we collected 69 samples of C. greeningi to investigate their intraspecific diversification (distributed in the Caatinga) and compare their historical demographics with that of A. brunoi, considering that the species found in distinct and adjacent biomes would have experienced expansions and contractions of an antagonistic form. Corythomantis greeningi presented a weak geographic structuring for the mitochondrial ND2 gene but not for the COI. Analysis of nDNA revealed the existence of two populations, one distributed to the east and one to the west. The demographic analyzes for C. greeningi indicate that eastern population underwent expansion as observed for other species of anurans of the biome and the western population suffered a retraction during the LGM. We suggest the western population may have been subject to shrinkage due to invasion of wetlands in the Caatinga before its expansion. This dynamics was approximately synchronic and antagonistic to the retraction of the A. brunoi population south of the AF, possibly reflecting the antagonistic geographic dynamics of the Caatinga and AF biomes in the LGM. The evolutionary history of the organisms studied here, in general, suggests that the past of the biomes in which they are is complex and its history is complementary.
In this dissertation we explored the diversification of anuran species of the Lophyohylini Tribe distributed in the Atlantic Forest (AF) and Caatinga biomes of Brazil. To do so, we used genomic data and methods of statistical phylogeography to analyze them, a robust and until then still scarce approach in the phylogeography of South American organisms. Through the Sanger sequencing we sampled mitochondrial DNA (mtDNA) and through high-throughput sequencing we obtained single nucleotide polymorphisms (SNPs) from nuclear DNA (nDNA). In the first chapter, we collected 82 samples of the species Aparasphenodon brunoi that is distributed in the low and coastal lands of the AF biome, being considered ideal to investigate the role of Pleistocene climatic instability in its diversification process. In the first chapter, to evaluate the influence of philopatric behavior, associated with differences in reproductive mode, dispersion and consequent gene flow among populations, we also collected 72 samples of A. arapapa and A. aff. brunoi species. These are sympatric species with a narrower distribution and with contrasting reproductive modes, making them ideal for this type of comparison. According to the inference based on demographic models, around the last glacial maximum (LGM) the northern population of A. brunoi remained stable while the southern one experienced a bottleneck followed by recent expansion. In addition, the northern population of A. brunoi exhibits greater nuclear diversity than the southern population. The paleomodeling distribution of A. brunoi corroborates the disjoint pattern of the northern and southern populations as well as the relictual distribution of the species in the LGM when the continental shelf is not considered as an area of expansion of the AF. Thus, we suggest that the diversification in A. brunoi is in line with the hypothesis of Pleistocene refuges for AF. As for the second aspect studied in the first chapter, we detected similarity in the pattern of diversity and inbreeding for A. arapapa and A. aff. brunoi, contradicting our expectations. We suggest that the philopatric behavior of A. arapapa males should not act strongly in limiting the dispersion of the species. In the second chapter, we collected 69 samples of C. greeningi to investigate their intraspecific diversification (distributed in the Caatinga) and compare their historical demographics with that of A. brunoi, considering that the species found in distinct and adjacent biomes would have experienced expansions and contractions of an antagonistic form. Corythomantis greeningi presented a weak geographic structuring for the mitochondrial ND2 gene but not for the COI. Analysis of nDNA revealed the existence of two populations, one distributed to the east and one to the west. The demographic analyzes for C. greeningi indicate that eastern population underwent expansion as observed for other species of anurans of the biome and the western population suffered a retraction during the LGM. We suggest the western population may have been subject to shrinkage due to invasion of wetlands in the Caatinga before its expansion. This dynamics was approximately synchronic and antagonistic to the retraction of the A. brunoi population south of the AF, possibly reflecting the antagonistic geographic dynamics of the Caatinga and AF biomes in the LGM. The evolutionary history of the organisms studied here, in general, suggests that the past of the biomes in which they are is complex and its history is complementary.
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Palavras-chave
Anfíbio, Mata Atlântica, Caatinga, Hipótese dos refúgios, Florestas tropicais sazonalmente secas, SNPs, DNA mitocondrial, Sequenciamento de alto rendimento, Paleomodelagem, Amphibians, Atlantic Forest, Refuge hypothesis, Seasonally dry tropical forests, Mitochondrial DNA, High throughput sequencing, Paleomodeling