Relationship between genetic and phenotypic variations in natural populations of perennial and biennial sagebrush

Abstract

Plant responses to environmental heterogeneity depend on life-history traits, which could relate to phenotypical and genetic characteristics. To elucidate this relationship, we examined the variation in population genetics and functional traits of short- and a long-lived Artemisia species that are co-occurring in the steppes of Mongolia. Mongolian steppes represent stressful, waterlimited habitats demanding phenotypic modifications in the short term and/or genetic adaptation in the long term. However, detailed knowledge is missing about both plant phenotypic and genetic differentiation and their inter-relationships in temperate grasslands. Here, we investigated 21 populations of the widely distributed subshrub A. frigida and the herbaceous biennial A. scoparia. Genetic variation was assessed with newly developed Simple Sequence Repeats (SSRs) markers. Functional trait data was collected from each individual, and data on environmental variables was collected for each population. We detected significantly higher genetic diversity in the biennial species (H E =0.86) compared to the perennial (H E =0.79). For both species, the largest share of genetic variation was partitioned within populations (96%). Population genetic structure in the biennial A. scoparia was weak, while the perennial A. frigida showed some spatial genetic structure, which was impacted by geographical factors, soil nutrients, and precipitation. Morphology-related functional traits (i.e., plant height) were predominantly associated with environmental variables rather than with genetic variation, while physiology-related traits (i.e., specific leaf area) were partly genetically determined.