Effect of altitude on the genetic structure of an Alpine grass, Poa hiemata.
OBJECTIVE
The persistence of plants inhabiting restricted alpine areas under climate change will depend upon many factors including levels of genetic variation in adaptive traits, population structure, and breeding system.


METHODS
Using microsatellite markers, the genetic structure of populations of a relatively common alpine grass, Poa hiemata, is examined across three altitudinal gradients within the restricted Australian alpine zone where this species has previously been shown to exhibit local adaptation across a narrow altitudinal gradient.


RESULTS
Genetic variation across six microsatellite markers revealed genetic structuring along altitudinal transects, and a reduction in genetic variation at high and low altitude extremes relative to sites central within transects. There was less genetic variation among transect sites compared with altitudinal gradients within transects, even though distances among transects were relatively larger. Central sites within transects were less differentiated than those at extremes.


CONCLUSIONS
These patterns suggest higher rates of gene flow among sites at similar altitudes than along transects, a process that could assist altitudinal adaptation. Patterns of spatial autocorrelation and isolation by distance changed with altitude and may reflect altered patterns of dispersal via pollen and/or seed. There was evidence for selfing and clonality in neighbouring plants. Levels of gene flow along transects were insufficient to prevent adaptive changes in morphological traits, given previously measured levels of selection.
Byars
Sean G
SG
Centre for Environmental Stress and Adaptation Research, Department of Genetics, Melbourne University, Parkville, Australia. s.byars@pgrad.unimelb.edu.au
Parsons
Yvonne
Y
Hoffmann
Ary A
AA
D000531:Altitude; D001483:Base Sequence; D017931:DNA Primers; D017343:Genes, Plant; D005819:Genetic Markers; D018895:Microsatellite Repeats / Q000235:genetics; D031785:Poa / Q000235:genetics*
D017931:DNA Primers; D005819:Genetic Markers