Geographical patterns of turnover and nestedness-resultant components of allelic diversity among populations
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2012
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Resumo
The analysis of geographical patterns in population
divergence has always been a powerful way to infer
microevolutionary processes involved in population differentiation,
and several approaches have been used to
investigate such patterns. Most frequently, multivariate
spatial patterns of population differentiation are analyzed
by computing pairwise genetic distances or FST (or related
statistics, such as /ST from AMOVA), which are then
correlated with geographical distances or landscape features.
However, when calculating distances, especially
based on presence-absence of alleles in local populations,
there would be a confounding effect of allelic richness
differences in the population differentiation. Moreover, the
relative magnitude of these components and their spatial
patterns can help identifying microevolutionary processes
driving population differentiation. Here we show how
recent methodological advances in ecological community
analyses that allows partitioning dissimilarity into turnover
(turnover) and richness differences, or nestedness-resultant
dissimilarity, can be applied to allelic variation data, using
an endemic Cerrado tree (Dipteryx alata) as a case study.
Individuals from 15 local populations were genotyped for
eight microsatellite loci, and pairwise dissimilarities were
computed based on presence-absence of alleles. The turnover
of alleles among populations represented 69 % of
variation in dissimilarity, but only the richness difference component shows a clear spatial structure, appearing as a
westward decrease of allelic richness. We show that
decoupling richness difference and turnover components of
allelic variation reveals more clearly how similarity among
populations reflects geographical patterns in allelic diversity
that can be interpreted in respect to historical range
expansion in the species.
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Allelic richness, Autocorrelation, Cerrado, Spatial genetic structure, Correlograms, Population divergence, Dipteryx alata, Mantel test
Citação
DINIZ-FILHO, Jose Alexandre Felizola et al. Geographical patterns of turnover and nestedness-resultant components of allelic diversity among populations. Genetica, Dordrecht, v. 140, p. 189-195, 2012.