Tropical Biology Section
Roncal, Julissa , Francisco-Ortega, Javier , Lewis, Carl .
Genetic and habitat differentiation of Geonoma macrostachys (Arecaceae) Western Amazonian varieties.
THE latest taxonomic account for the palms of the Amazon recognizes two common and widespread varieties of Geonoma macrostachys (Arecaceae) in Western Amazonia: acaulis and macrostachys. These varieties are joined by intermediates, which obscure their taxonomic boundaries. An evaluation of the genetic distinctness between G. macrostachys varieties at a regional scale, and the habitat preference of sympatric varieties are presented. Thirty-one G. macrostachys individuals were randomly sampled from four Peruvian tropical moist forests. Twenty-seven ISSR primers were used, and of the 99 ISSR bands produced, 51.52% were polymorphic. Clustering, ordination and AMOVA suggested a lack of genetic distinctness between varieties at the regional level. Individuals clustered by geographical provenance and two main groups were identified. A hierarchical AMOVA revealed that the genetic diversity in G. macrostachys mainly lies among localities (76.58%). We do not support the recognition of the two taxonomic varieties. We studied habitat differentiation with respect to edaphic, topographic, and light conditions in three Peruvian forests. Results showed that the two varieties were mostly encountered in different physiographically defined habitats with variety acaulis occurring preferentially in floodplain forest and variety macrostachys in tierra firme. Principal component analysis of a plot by environmental variables matrix segregated plots and varieties by habitat in each forest. Edaphic factors, primarily soil texture and K content, contributed more than light conditions to this differentiation. Thus, there is evidence of parallel, local phenotypic diversification resulting in similar but unrelated morphological forms in distinct areas across the distribution range, and habitat differentiation might play a role in the local coexistence of these closely related taxa.
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1 - Fairchild Tropical Botanic Garden, Center for Tropical Plant Conservation, 11935 Old Cutler Road, Coral Gables, Miami, Florida, 33156-4242, USA
2 - Florida International University, Deparment of Biological Sciences, 11200 SW 8th St., Miami, Florida, 33199, USA
inter-simple sequence repeat
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 11:15 AM