Contrasting spatial genetic structure in Annona crassiflora populations from fragmented and pristine savannas
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2014
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Resumo
In continuous populations, fine-scale genetic
structure tends to be stronger in species with restricted
pollen and seed dispersal. However, habitat fragmentation
and disturbances can affect genetic diversity and spatial
genetic structure due to disruption in ecological processes,
such as plant reproduction and seed dispersal. In this study,
we compared the genetic diversity and fine-scale spatial
genetic structure (SGS) in two populations of Annona
crassiflora (Annonaceae) in a pristine savanna Reserve
(ESECAE) and in a fragmented disturbed savanna area
(PABE), both in Cerrado biome in Central Brazil. The
analyses were based on the polymorphism at 10 microsatellite
loci. Our working hypothesis was that SGS is
stronger and genetic diversity is lower in population at
fragmented area (PABE) than at pristine area (ESECAE).
Both populations presented high levels of polymorphism
and genetic diversity and showed no sign of bottleneck for
both Wilcoxon sign-rank test for heterozygosity excess
(p[0.05) and coalescent analyses (growth parameter
g not different from zero), but population at fragmented
area showed higher fixation index and stronger SGS.
Besides, populations are significantly differentiated
(FST = 0.239, RST = 0.483, p\0.001 for both). Coalescent
analyses showed high historical effective population
sizes for both populations, high gene flow between ESECAE and PABE and recent time to most recent common
ancestor (*37 k year BP). Our results suggest that
despite the high genetic diversity, fragmentation and disturbance
may have been affecting populations of this species
increasing mating between closely related individuals
leading to high fixation index and strong SGS.
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Annonaceae, Cerrado biome, Coalescence, Genetic diversity, Gene flow, Neotropical tree
Citação
COLLEVATTI, Rosane G. et al. Contrasting spatial genetic structure in Annona crassiflora populations from fragmented and pristine savannas. Plant Systematics and Evolution, Heidelberg , v. 300, p. 1719-1727, 2014.