Phylogenetic relationships of the Oxytropis campestris and Oxytropis arctica complexes in Alaska inferred from non-coding nuclear DNA and RAPD data

Abstract

The taxonomy and evolutionary relationships of the Oxytropis arctica and Oxytropis campestris complexes in Alaska are poorly understood. Taxonomic disagreement has centered on which morphological characters are important in circumscribing these taxa. Several of these taxa are endemic to Alaska, including Oxytropis arctica var. barnebyana, which is currently of conservation concern. Internal transcribed spacer sequences and randomly amplified polymorphic DNA markers were employed to circumscribe these taxa. Both lines of evidence revealed one major dichotomy dividing northern populations from western populations. There is weak support for traditional taxonomies. Morphological characters used to separate these taxa do not assort to either side of the dichotomy. These traits may be controlled by one or a few genes and may not represent degrees of divergence. They may have been derived independently in each population in response to adaptation to local environmental conditions, changing quickly in response to natural selection, genetic drift, mutation, or migration.