Regional variation in Argentinean populations of <i>Bromus catharticus</i> (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. Treinta y una poblaciones de Bromus catharticus Vahl., recolectadas en el dominio Pampeano (Argentina), fueron clasificadas utilizando 24 caracteres altamente heredables por métodos de taxonomía numérica. Tras implementar el análisis discriminante del paso a paso (Stepwise), 18 variables fueron seleccionadas como variables clasificatorias. Ocho grupos de poblaciones fueron clasificadas en dos clusters principales. Diferentes morfotipos, principalmente asociados a la arquitectura de las panojas y a variables microflorales, fueron encontrados. El patrón de variación morfológico parece responder a un gradiente de humedad y temperatura que disminuye desde el NE al SW. Además, dicho patrón de clasificación refleja un origen geográfico para la mayoría de las poblaciones, aunque hubo algo de ruido. Nuestros resultados se ajustan a un modelo de variación en parches, donde las poblaciones están genéticamente seleccionadas por condiciones micro y macro ambientales.

Salinity Tolerance in Argentinean Population of &lt;i&gt;Bromus catharticus&lt;/i&gt;. Variability and Direct and Indirect Effects on Seedling Characters

“…A patchy morphological variation model, genetically adapted to macro and micro environmental conditions, was detected in B. catharticus populations, collected at the Pampas region [18] [19]. Germplasm collected from saline habitats could ensure the identification of genes tolerant to this stress.…”