Filogeografia e estrutura genética de uma árvore de floresta estacional neotropical Tabebuia roseoalba (RIDL.) Sandwith (Bignnoniaceae)
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2014-09-29
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Universidade Federal de Goiás
Resumo
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.
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MELO, W. A. Filogeografia e estrutura genética de uma árvore de floresta estacional neotropical Tabebuia roseoalba (RIDL.) Sandwith (Bignnoniaceae). 2014. 66 f. Dissertação (Mestrado em Genética e Biologia Molecular) - Universidade Federal de Goiás, Goiânia, 2014.