Phenotypical variation and taxonomic correlates of five closely related Andean species of Poa (Poaceae) along geographic and climatic gradients

LIDIA R. SCRIVANTI ; LUCIANA MESTRE; ANA M. ANTON

Phytotaxa

Magnolia Press

Año: 2014 vol. 183 p. 121 - 144

1179-3155

Poa anfamensis, P. jujuyensis, P.lilloi, P. parviceps and P. scaberula (Poaceae) are a group of morphologically similar species.These species inhabit cool grasslands and mesic puna. They are highly polymorphic and their circumscriptions areuncertain, especially the entities around P. scaberula. Univariate and multivariate analyses (PCA and DA) were conductedto evaluate the morphological variation among 150 herbarium specimens identified as P. anfamensis, P. jujuyensis, P. lilloi,P. parviceps and P. scaberula. Forty morphological characters were included and their patterns of variation were analyzedamong specimens, together with their relationship with environmental variables, using correlation analysis. The relationshipsbetween morphological variation and geographical distance, and climatic variables among specimens, were comparedwith Mantel permutation tests. Taxa were delimited according to the observed clustering of specimens in the PCA plots andDA, and diagnostic characters were identified. The five taxa showed continuous morphological variation. Morphologicalvariation is explained by geographical and climatic factors such as elevation, geographical distance, latitudinal and longitudinalgradients, temperature and precipitation in the different sites in the Andes. Altitudinal and geographical distance are apparentlymore decisive factors in phenotypic differentiation and could have played a large role in interspecific differentiationamong Poa entities, as shown by the stronger and significant association between vegetative and reproductive phenotype andaltitudinal distance, and between vegetative and reproductive phenotype and geographical distance. In addition, we observeduncoupling among vegetative and floral characters in Poa specimens that grow along environmental gradients; these charactersare responding independently to different abiotic forces promoting genetic divergence and speciation. Based on theresults, P. anfamensis and P. parviceps are synonymised with P. scaberula, and P. jujuyensis is synonymised with P. lilloi.