Kriebel, Ricardo , Michelangeli, Fabián Armando .
Phylogeny of Conostegia (Melastomataceae) reveals multiple losses of herkogamy.
Conostegia is a genus within the exclusively Neotropical and berry fruited tribe Miconieae, and consists of about 42 species concentrated in Northern South America, Central America and the Caribbean. Traditionally Conostegia has been defined by the combination of having a calyptrate calyx that dehisces at anthesis, and pleiostemonous flowers (having more than double the number of stamens than petals). To test the monophyly of Conostegia, we gathered sequence data from two nuclear loci (nrITS and nrETS) and four chloroplast spacers (accD-psaI, atpF-H, psbKL, trnS-G) for thirty of the forty two recognized species. Our results corroborate previous molecular phylogenetic studies which demonstrated that Conostegia is paraphyletic and includes several species currently in Clidemia and Miconia, although not Leandra subulata and Tococa spadiciflora as had been found in previous analyses. The calyptrate calyx has evolved at least three times independently in the Conostegia clade and was lost at least once. The degree of pleiostemony appears to be correlated to the type of herkogamy present. Four types of herkogamy were observed in the Conostegia clade, approach herkogamous flowers in which the style is exserted well beyond the anthers, a second type of approach herkogamous flowers similar to the first but with the style also bending to one side of the flower, a third type of approach herkogamous flowers with the style the same length as the stamens but deflected in opposite direction to them, and blossoms with giant stigmas which are hypothesized to be large pollen receivers. The latter four types of herkogamy help to diagnose subclades within Conostegia. In addition, herkogamy has been lost at least three times within the Conostegia clade. Only species within two of the non herkogamous subclades have reached the Caribbean islands. Our data in addition to published observations of self-compatibility in non herkogamous Conostegia montana lead us to hypothesize that the loss of herkogamy is a pre-adaptation for long distance dispersal and successful colonization.
Log in to add this item to your schedule
1 - The New York Botanical Garden / Graduate Center, CUNY, 2900 Southern Blvd., Bronx, NY, 10458, USA
2 - The New York Botanical Garden, Institute Of Systematic Botany, 2900 Southern Blvd., Bronx, NY, 10458, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell B/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 8:45 AM