Phylogeography of the tree Hymenaea stigonocarpa (Fabaceae: Caesalpinioideae) and the influence of quaternary climate changes in the Brazilian cerrado.
OBJECTIVE
Hymenaea stigonocarpa (Fabaceae: Caesalpinioideae) is an endemic tree from the Brazilian cerrado (savanna vegetation), a biome classified as a hotspot for conservation priority. This study investigates the phylogeographic structure of H. stigonocarpa, in order to understand the processes that have led to its current spatial genetic pattern.


METHODS
The polymorphism level and spatial distribution of variants of the plastid non-coding region between the genes psbC and trnS were investigated in 175 individuals from 17 populations, covering the greater part of the total distribution of the species. Molecular diversity indices were calculated and intra-specific relationships were inferred by the construction of haplotype networks using the median-joining method. Genetic differentiation among populations and main geographical groups was evaluated using spatial analysis of molecular variance (SAMOVA).


RESULTS
Twenty-three different haplotypes were identified. The level of differentiation among the populations analysed was relatively high (F(ST) = 0.692). Phylogeographic analyses showed a clear association between the haplotype network and geographic distribution of populations, revealing three main geographical groups: western, central and eastern. SAMOVA corroborated this finding, indicating that most of the variation can be attributed to differences among these three groups (58.8 %), with little difference among populations within groups (F(SC) = 0.252).


CONCLUSIONS
The subdivision of the geographic distribution of H. stigonocarpa populations into three genetically differentiated groups can be associated with Quaternary climatic changes. The data suggest that during glacial times H. stigonocarpa populations became extinct in most parts of the southern present-day cerrado area. Milder climatic conditions in the north and eastern portions of the cerrado resulted in maintenance of populations in these regions. Thus it is inferred that the most southern part of the present-day cerrado was re-colonized by different lineages from northern parts of this biome, after postglacial climate amelioration.
Ramos
Ana Carolina Simões
AC
Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Caixa Postal 486, 31270-901 Belo Horizonte, MG, Brazil.
Lemos-Filho
José Pires
JP
Ribeiro
Renata Acácio
RA
Santos
Fabrício Rodrigues
FR
Lovato
Maria Bernadete
MB
D001938:Brazil; D002980:Climate; D018742:DNA, Chloroplast / Q000737:chemistry / Q000235:genetics; D007887:Fabaceae / Q000145:classification / Q000235:genetics*; D014644:Genetic Variation; D005843:Geography; D006239:Haplotypes; D010802:Phylogeny; D017422:Sequence Analysis, DNA
D018742:DNA, Chloroplast