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Abstract Detail



Systematics Section/ASPT

Kriebel, Ricardo [1], Michelangeli, Fabian [2].

Syndromes within syndromes: floral diversification in buzz pollinated Conostegia (Melastomataceae, Miconieae).

Most species of Melastomataceae have poricidal anthers that are buzzed by female bees. Because buzzed plants offer pollen as a reward, they are thought to receive pollen at the same time they deliver it. Being simultaneously male and female results in self pollination or intrafloral sexual conflict. To deal with these issues, the Melastomataceae tend to have flowers with exerted styles (herkogamy). Until now, no attempt has been made to quantify floral diversification including herkogamy in a clade of Melastomataceae. To do so, we generated a phylogeny of Conostegia using six DNA regions. We then measured 21 floral traits for 41 species from liquid preserved flowers representing three major clades recovered. PCA was conducted on the 21 characters to obtain floral shape variables. Herkogamy was measured to test for a correlation with floral shape. The results show that most characters are correlated but style length is not, and that style length had no phylogenetic signal, whereas most other characters did. Ancestral state reconstructions of flower shape against herkogamy revealed four general flower types: a) large multiparted herkogamous flowers, b) non herkogamous flowers, c) large multiparted flowers with short styles and large stigmas, and d) small non multiparted herkogamous flowers. To detect convergent evolution of floral types without a priori groupings we used a recently developed comparative method called SURFACE. This analysis recovered almost identically our floral group designations and detected convergent evolution in flower types a) and b). To test the adaptive significance of floral morphology, we obtained environmental data, range sizes, and presence of taxa in the Caribbean islands. No correlation between floral morphology and environment was found except for the giant stigma clade that occurs at higher elevations. Regarding range size, species with short style had overall larger ranges and are the only ones to have reached the Caribbean islands. In conclusion we found four floral types in the Conostegia clade, two of which have evolved independently. In addition, no correlation between floral shape and herkogamy was found. The latter finding is surprising since natural selection is supposed to increase floral integration for efficient pollination. A hypothesis for this result is the inherent dynamics of being simultaneously male and female. Short styles may permit self pollination and establishment in new habitats with unpredictable pollinators explaining the presence of oceanic island endemics. Exerted styles have not re-evolved in Conostegia but an alternative solution appears to be a giant stigma.

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1 - CUNY and The New York Botanical Garden, Biology, 2900 Southern Blvd, Bronx, NY, 10458, USA
2 - The New York Botanical Garden, Institute of Systematic Botany, 2900 Southern Blvd., Bronx, NY, 10458, USA

Keywords:
pollination syndromes
Conostegia
Herkogamy
diversification
Miconieae
morphometrics
floral evolution
Elliptical Fourier Analysis.

Presentation Type: Oral Paper:Papers for Sections
Session: 13
Location: Rosedown/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 2:30 PM
Number: 13005
Abstract ID:607
Candidate for Awards:George R. Cooley Award


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