PARENT SESSION
Poster Session # 21: Biogeography, Biodiversity, Populations, and Genetics.

Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Genetic, quantitative, environmental and geographical distances among populations of a dominant C4 grass from Neotropical savannas.

Baruch, Zdravko^*,1, Nassar, Jafet³, Bubis, José², Torrealba, Karimar¹, ¹ Universidad Simón Bolívar, Caracas, Miranda, Venezuela, Venezuela³ Universidad Simón Bolívar, Caracas, Miranda, Venezuela, Venezuela² Instituto Venezolano de Investigaciones Científicas, Caracas, Miranda, Venezuela, Venezuela

ABSTRACT- The Orinoco savannas in Venezuela are exposed to land use changes, contamination and biological invasions which compromise their persistence and function. Trachypogon plumosus dominates the herbaceous matrix of the savannas under diverse combinations of climate and soils, suggesting substantial inter-population variation. We quantified isozyme and quantitative trait variation in nine populations of this grass and related estimates to geographic and environmental features of sampled locations. Isozyme diversity estimates were based on 10 polymorphic enzyme systems. Also, 16 quantitative traits were evaluated. Distance matrices for isozyme, quantitative traits, geographic and environmental data were subjected to cluster analysis and ordination. Correspondence between isozyme and quantitative trait variation and their relationships to geographic and environmental distances were analyzed with Mantel tests. Isozyme and quantitative trait diversity differed significantly among populations. About 28% of total isozyme variation occurred among populations. A significant association was only detected between genetic and geographic distances; however, dendrograms generated for isozyme and quantitative traits were congruent with environmental and geographic data and ecologically meaningful. The core of lowland and highland populations were clearly defined leaving 2 - 3 populations without clear affinities. Our results support the genetic basis of local population differentiation and the relatively large intra-specific diversity in T. plumosus. They also can be used to decide conservation strategies and select seed sources for future restoration programs.

Key words: C4 grass, Interpopulation diversity, tropical savanna, isozymes