Abstract
Knowledge of the role of Neotropical montane landscapes in shaping genetic connectivity and local adaptation is essential for understanding the evolutionary processes that have shaped the extraordinary species diversity in these regions. In the present study, we examined the landscape genetics, estimated genetic diversity, and explored genetic relationships with morphological variability and reproductive strategies in seven natural populations of Cattleya liliputana (Orchidaceae). Nuclear microsatellite markers were used for genetic analyses. Spatial Bayesian clustering and population-based analyses revealed significant genetic structuring and high genetic diversity (He = 0.733 ± 0.03). Strong differentiation was found between populations over short spatial scales (FST = 0.138, p < 0.001), reflecting the landscape discontinuity and isolation. Monmonier´s maximum difference algorithm, Bayesian analysis on STRUCTURE and principal component analysis identified one major genetic discontinuity between populations. Divergent genetic groups showed phenotypic divergence in flower traits and reproductive strategies. Increased sexual reproductive effort was associated with rock outcrop type and may be a response to adverse conditions for growth and vegetative reproduction. Here we discuss the effect of restricted gene flow, local adaptation and phenotypic plasticity as drivers of population differentiation in Neotropical montane rock outcrops.
Highlights
Tropical mountains play an important role in promoting regional and global biodiversity [1]
Bayesian modelling of population membership probability and Analysis of Molecular Variance (AMOVA) results showed a significant genetic differentiation in accordance with outcrop and mountain discontinuities suggesting that landscape contributes to genetic isolation at outcrop environments, even at short distances
The most significant pattern revealed by the use of microsatellite markers was the deep population differentiation between the Serra do Caraça and core Iron Quadrangle (IQ) groups
Summary
Tropical mountains play an important role in promoting regional and global biodiversity [1]. Tropical montane landscapes combine discontinuous distribution with edapho-climatic variations resulting from altitudinal gradients Because of their disconnected geographic nature, rock outcrops are frequently compared with oceanic islands, since most of them display a marked ecological isolation from the surrounding area. The basic concept and tools developed to study island biogeography, along with new methodological developments to include spatial and temporal data regarding population genetics and genomics, can be applied to evolutionary studies in this context. This approach would provide insights on mechanisms and patterns of species diversification [26,27,28,29,30]. Understanding the pattern of genetic connectivity, gene flow and local adaptations has clear implications for the proper management of genetic diversity in threatened populations [30,31]
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