Population differentiation and species cohesion in two closely related plants adapted to neotropical high-altitude 'inselbergs', Alcantarea imperialis and Alcantarea geniculata (Bromeliaceae)

Isolated granitic rock outcrops or 'inselbergs' may provide a window into the molecular ecology and genetics of continental radiations under simplified conditions, in analogy to the use of oceanic islands in studies of species radiations. Patterns of variability and gene flow in inselberg...

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Bibliographic Details
Published in:Molecular ecology 2007-05, Vol.16 (10), p.1981-1992
Main Authors: BARBARÁ, T, MARTINELLI, G, FAY, M.F, MAYO, S.J, LEXER, C
Format: Article
Language:English
Subjects:
adaptive radiation
Altitude
Bayes Theorem
Brazil
Bromeliaceae
Bromeliaceae - genetics
bromeliad
Cluster Analysis
Color
Ecosystem
gene flow
Gene Flow - genetics
Gene Frequency
Genetic diversity
Genetic Variation
Genetics, Population
Genotype
Geology
inselberg
microsatellite repeats
Microsatellite Repeats - genetics
microsatellites
Molecular biology
Phylogeny
Plant ecology
Plant populations
Population genetics
species cohesion
Species Specificity
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Summary:Isolated granitic rock outcrops or 'inselbergs' may provide a window into the molecular ecology and genetics of continental radiations under simplified conditions, in analogy to the use of oceanic islands in studies of species radiations. Patterns of variability and gene flow in inselberg species have never been thoroughly evaluated in comparison to related taxa with more continuous distribution ranges, or to other species in the same kingdom in general. We use nuclear microsatellites to study population differentiation and gene flow in two diploid, perennial plants adapted to high-altitude neotropical inselbergs, Alcantarea imperialis and Alcantarea geniculata (Bromeliaceae). Population differentiation is pronounced in both taxa, especially in A. imperialis. Gene flow in this species is considerably lower than expected from the literature on plants in general and Bromeliaceae in particular, and too low to prevent differentiation due to drift (Nem < 1), unless selection coefficients/effect sizes of favourable alleles are great enough to maintain species cohesion. Low gene flow in A. imperialis indicates that the ability of pollinating bats to promote gene exchange between inselbergs is smaller than previously assumed. Population subdivision in one inselberg population of A. imperialis appears to be associated with the presence of two colour morphs that differ in the coloration of rosettes and bracts. Our results indicate a high potential for inselbergs as venues for studies of the molecular ecology and genetics of continental radiations, such as the one that gave rise to the extraordinary diversity of adaptive strategies and phenotypes seen in Bromeliaceae.
ISSN:0962-1083
1365-294X
DOI:10.1111/j.1365-294X.2007.03272.x