Abstract Detail

Systematics Section/ASPT

Sosa, Karla [1], Kriebel, Ricardo [2], Michelangeli, Fabian [3], Guimaraes, Paulo J [4].

Androecium Evolution in the Melastomeae (Melastomataceae).

The tribe Melastomeae (Melastomataceae) comprising around 870 species in 47 genera from the new and old world tropics, is known for having a high diversity of anther morphology. We generated a multi-locus phylogeny (nrITS, nrETS, accD-psaI and psbK-psbL) for over 200 species in 40 genera of the tribe. In order to study the evolution of the androecium we also generated a morphological matrix for 29 anther characters for over 70 species that encompass the morphological variation within the tribe. Dimorphic anthers, a condition also known as heteranthery, have evolved several times within the tribe, and this can take the form of size difference or size and shape difference. When there is differentiation in form and size of the anthers , then it can also be followed by color differentiation, with the thecae in the larger anthers being pink, purple or fuchsia, and the anther appendages as well as the small anthers all being yellow. Anther appendages and dimorphism have being lost in some high elevation groups (i.e. Chaetolepis and allies). The evolution of anther dimorphism and appendages in Monochetum seems to have a different developmental path as in the rest of the groups, as appendages are all dorsal (vs. ventral in other Melastomeae) and the large anthers are antipetalous (vs antisepalous in all other Melastomeae). Species without heteranthery usually have all the stamens arranged in a circle, giving the flower an actinomorphic appearance, while all groups with dimorphic anthers have the anthers flexed to one side of the flower at anthesis, giving the flowers a zygomorphic appearance. These differences in anther position may play a role in pollen deposition from each set of dimorphic anthers. Detailed pollinator behavior studies are now needed to test Darwin's division of labor hypotheses in a phylogenetic context in light of these results.

Broader Impacts:

1 - Columbia University, New York, NY, 10027, USA
2 - New York Botanical Garden, 357 East 201 St Apt. 3f, Bronx, NY, 10458, USA
3 - The New York Botanical Garden, Institute of Systematic Botany, 2900 Southern Blvd., Bronx, NY, 10458, USA
4 - Jardim Botanico de Rio de Janeiro, Rio de Janeiro, RJ, Brazil

Keywords:
Melastomataceae
Anther
Stamen
Androecium.

Presentation Type: Oral Paper:Papers for Sections
Session: 39
Location: Elmwood/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 8:45 AM
Number: 39002
Abstract ID:648
Candidate for Awards:None