Filogeografia e estrutura genética de uma árvore de floresta estacional neotropical Tabebuia roseoalba (RIDL.) Sandwith (Bignnoniaceae)

• Autor(a) principal: Melo, Warita Alves de
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/001300000b14m
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/5594
• topic: Coalescência; cpDNA; Mudanças climáticas do Quaternário; Coalescence; cpDNA; Quaternary climatic changes; GENETICA::GENETICA VEGETAL

Tabebuia roseoalba (RIDL.) Sandwith (Bignoniaceae) is widely distributed in Neotropical seasonally dry forests, occurring mainly from Northeast towards the Central West and Southeast Brazil, and also in Paraguay, Bolivia and Peru. The phylogeography of this species may help us to understand how historical events influenced its genetic diversity and in the current geographic distribution of seasonally dry forests. The results were based on the sequencing of three chloroplast intergenic spacers (psbA-trnH, trnC-ycf6 and trnStrnG2S) and the nuclear ribosomal region (nrDNA) (ITS1 + 5.8S + ITS2). We sampled 18 populations (235 individuals) in North, Central West and Southeast. The three chloroplast regions generated a fragment of 1,519 base pairs and 37 haplotypes. We found high haplotype diversity (h = 0.839) and low nucleotide diversity (π = 0.00610 SD = 0.00311) and were found. A fragment of 506 base pairs was generated for nrDNA and 14 haplotypes were identified. The haplotype diversity (h = 0.336) was lower than chloroplast diversity but nucleotide diversity (π = 0.01669 SD = 0.00857) was higher. Populations of Tabebuia rosealba are highly differentiated (FST = 0. 684; p = 0.001) with low gene flow (Nm < 1.0) among all population pairs. Our results also showed significant population reduction followed by expansion (Mismatch Distribution SSD = 0.20746; p = 0.0002, Tajima D = - 1.766; p = 0.008, Fs = - 23.702; p = 0.001), and the Extended Bayesian Skyline Plot (EBSP) also showed population reduction. Coalescent dated tree showed an ancient time to most recent ancestor (TMRCA) dated from ~4.9 Ma (CI 95% 1.9 Ma) in the Pliocene. Both the median-joining network and the coalescent tree showed evidences of incomplete lineage sorting. Our data show that the current pattern of diversity found so far is in consonance with a wide distribution of this species in the past, strongly suggesting that the climate changes of the Quaternary Period had strongly influenced the genetic diversity pattern and the geographical distribution of the species.