Demographic history and the low genetic diversity in Dipteryx alata (Fabaceae)
from Brazilian Neotropical savannas |
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Authors: | R G Collevatti M P C Telles J C Nabout L J Chaves T N Soares |
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Institution: | 1.Departamento de Biologia Geral,
Laboratório de Genética & Biodiversidade, Instituto de Ciências
Biológicas, Universidade Federal de Goiás, Goiânia, Brazil;2.Unidade de Ciências Exatas e
Tecnológica (UnUCET), Universidade Estadual de Goiás, Anápolis, Brazil;3.Escola de Agronomia e Engenharia de
Alimentos, UFG, Goiânia, Brazil |
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Abstract: | Genetic effects of habitat fragmentation may be undetectable because they are generally a
recent event in evolutionary time or because of confounding effects such as historical
bottlenecks and historical changes in species'' distribution. To assess the effects
of demographic history on the genetic diversity and population structure in the
Neotropical tree Dipteryx alata (Fabaceae), we used coalescence analyses coupled
with ecological niche modeling to hindcast its distribution over the last 21 000
years. Twenty-five populations (644 individuals) were sampled and all individuals were
genotyped using eight microsatellite loci. All populations presented low allelic richness
and genetic diversity. The estimated effective population size was small in all
populations and gene flow was negligible among most. We also found a significant signal of
demographic reduction in most cases. Genetic differentiation among populations was
significantly correlated with geographical distance. Allelic richness showed a spatial
cline pattern in relation to the species'' paleodistribution 21 kyr BP
(thousand years before present), as expected under a range expansion model. Our results
show strong evidences that genetic diversity in D. alata is the outcome of the
historical changes in species distribution during the late Pleistocene. Because of this
historically low effective population size and the low genetic diversity, recent
fragmentation of the Cerrado biome may increase population differentiation, causing
population decline and compromising long-term persistence. |
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Keywords: | Cerrado biome coalescence effective population size gene flow population structure ecological niche modeling |
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