1 Citation 275 Views 34 Downloads
The Cerrado is the largest South American savanna and encompasses
substantial species diversity and environmental variation. Nevertheless,
little is known regarding the influence of the environment on population
divergence of Cerrado species. Here, we searched for climatic drivers of
genetic (nuclear microsatellites) and leaf trait divergence in Annona
crassiflora, a widespread tree in the Cerrado. The sampling encompassed
all phytogeographic provinces of the continuous area of the Cerrado and
included 397 individuals belonging to 21 populations. Populations showed
substantial genetic and leaf trait divergence across the species'
range. Our data revealed three spatially defined genetic groups (eastern,
western and southern) and two morphologically distinct groups (eastern and
western only). The east-west split in both the morphological and genetic
data closely mirrors previously described phylogeographic patterns of
Cerrado species. Generalized linear mixed effects models and multiple
regression analyses revealed several climatic factors associated with both
genetic and leaf trait divergence among populations of A. crassiflora.
Isolation by environment (IBE) was mainly due to temperature seasonality
and precipitation of the warmest quarter. Populations that experienced
lower precipitation summers and hotter winters had heavier leaves and
lower specific leaf area. The southwestern area of the Cerrado had the
highest genetic diversity of A. crassiflora, suggesting that this region
may have been climatically stable. Overall, we demonstrate that a
combination of current climate and past climatic changes have shaped the
population divergence and spatial structure of A. crassiflora. However,
the genetic structure of A. crassiflora reflects the biogeographic history
of the species more strongly than leaf traits, which are more related to
current climate.
275 views reported since publication in 2016.