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ARS Home » Southeast Area » Miami, Florida » Subtropical Horticulture Research » Research » Publications at this Location » Publication #330522

Research Project: Genetic Characterization, Genetic Improvement, and Best Horticultural Management Practices for Subtropical/Tropical Ornamental Germplasm

Location: Subtropical Horticulture Research

Title: ATLANTIC RAIN FOREST AND CAATINGA VEGETATION DYNAMICS EXPLAIN PHYLOGEOGRAPHICAL PATTERN OF AN ENDEMIC BRAZILIAN PALM

Author
item De Lima, Natacia Evangel - Universidad De Sao Paulo
item Meerow, Alan
item Manfrin, Maura Helena - Universidad De Sao Paulo

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2016
Publication Date: 9/20/2016
Citation: De Lima, N.I., Meerow, A.W., Manfrin, M. 2016. ATLANTIC RAIN FOREST AND CAATINGA VEGETATION DYNAMICS EXPLAIN PHYLOGEOGRAPHICAL PATTERN OF AN ENDEMIC BRAZILIAN PALM. Meeting Abstract.

Interpretive Summary:

Technical Abstract: Technical Abstract Occurrence of a wetter and cooler climate associated with humid vegetation had been inferred for the Caatinga region during the late Pleistocene and early Holocene. The existence of rainforest migration routes in northeastern Brazil is widely recognized. Present-day rainforest natural enclaves –“Brejos de altitude”- are supposed to be remnants of this ancient rainforest that retracted at the onset of current Caatinga vegetation. Our aim was to investigate if past biomes dynamics may have influenced the geographical distribution of genetic variation in the endemic palm Acrocomia intumescens Drude (Arecaceae). Since the distribution of the species is restricted to Atlantic Rain Forest and “Brejos de altitude”, which is separated by large areas of seasonal dry forests (SDF) that could be barriers to gene flow, we hypothesized that populations are highly differentiated and that the SDF act as phylogeographic breaks. Samples were collected from the field across the spatial range in Brazil, including 62 individuals from 10 localities. Here we used a molecular data set based on polymorphism of five microsatellites (SSR) loci and two non-coding nuclear regions (PRK717-969 and WRKY16). Eight haplotypes were found for nuclear regions concatenated, and genetic diversity was low (He= 0.208; hPRK;WRKY=0.51; 0.296). Results of structure analyses suggested a k=2 for both nuclear sequence and SSR data; one cluster corresponded to “Brejos de altitude”, in deep interior of Caatinga, and the other included populations from Atlantic Forest on Brazilian coast. Hierarchical AMOVA showed significant differentiation among the populations (Fst PRK;WRKY=0.87; 0.42), although SSR data showed a lower structuration (Fst SSR=0.297). A significant correlation between genetic and geographical distance was verified for all markers (P < 0.02). All this suggested a contemporary and historical gene flow limitation between “Brejos de altitude” and Atlantic Forest populations. No significant effect of population retraction, followed by expansion, was observed for the species, either by mismatch distribution, Fu´s or Tajima’s neutrality tests (P = 0.10). The two groups of haplotypes and clusters identified represented genetic breaks, which were geographically coincident, and correlated with past forest invasions reported in the literature. Our data support the idea that past expansions of the Amazon and Atlantic forests over the current Caatinga distribution shaped the phylogeographical pattern of this palm.