Reginato, Marcelo , Michelangeli, Fabian .
Biogeography of Leandra sensu stricto (Melastomataceae): geographical range expansions, extinctions and the amphitropical pattern.
Leandra Raddi is a genus of neotropical shrubs, occasionally treelets, that belongs to the tribe Miconieae in the Melastomataceae. With over 250 accepted species, Leandra is second in number (to the 1100 of Miconia) in the tribe. The last taxonomic treatment for Leandra, currently under use, dates to the 19th century and divided the genus in seven sections. Recent studies using molecular data demonstrated that two of these sections are not closely related to the other ones. In the other five sections most species are endemic to the Atlantic Forest in eastern Brazil (ca. 200 species) and form a clade that also includes a few endemic members of Ossaea (ca. 15 spp.), Clidemia (2 spp.), and all 11 species of Pleiochiton. This clade contains the type of the genus and has been dubbed the Leandra sensu stricto group. Leandra s.s. is a highly diverse clade almost restricted to the Atlantic Forest, with many narrowly distributed species. During the course of our systematic studies of Leandra s.s. we found two species with striking disjunct distributions between eastern Brazil and northern Central America, that has not been discussed before. Disjunctions in the ranges of plant species are always intriguing and their interpretation is one of the central problems in biogeography. Amphitropical disjuncts are known from relatively few families and most taxa share a general pattern (north temperate origin, herbs from open areas, etc.). In order to understand the biogeographical pattern found in Leandra s.s. we gathered detailed distributional data for all species in this clade. Focusing on the species that occur outside the Atlantic Forest, the historical biogeography of the group was examined using track analysis, molecular clock dating, and climatic niche modeling. Our results suggests a scenario where: 1.very few species made it out the Atlantic Forest; 2. the similar distributional patterns (tracks) refute random long distant dispersal; 3. the disjunctions seems to have occurred at different times during the Pleistocene; 4. climatic niche modeling projections predicted a path of suitable areas through the Andes during the Last Glacial Maximum and under current data do not predict this same path. Taking all this into account, it seems that the amphitropical pattern found in Leandra s.s. might be explained by geographical range expansion followed by local extinctions during the Pleistocene
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1 - The New York Botanical Garden, Institute of Systematic Botany, 2900 Southern Blvd., Bronx, NY, 10458, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Franklin B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 2:30 PM