Regional variation in Argentinean populations of Bromus catharticus (Poaceae) as measured by morphological

Abstract

Thirty-one populations of Bromus catharticus Vahl., collected from the Pampean Dominion (Argentina), were classified using twenty four highly heritable traits by numerical taxonomic methods. After implementing a stepwise discriminant analysis, 18 traits were chosen as classificatory variables. Eight population groups were classified in two main clusters. Different morphotypes, primarily associated with panicle architecture and micro floral traits, were found. The patterns in the morphological variation seem to correspond to a gradient of humidity and temperature that diminishes from the NE to the SW. This pattern of classification reflects the geographical origin for most of the sampled populations, although there was some noise. Our results fit the patchy variation model, where populations are genetically selected for macro and micro environmental conditions.

Keywords

• bromus catharticus
• genetic variation
• morphotypes
• numerical taxonomy
• phenotypic variation
• quantitative traits
• rescue grass