Gowda, Vinita , Kress, John .
Role of heliconias in driving sex-specific adaptation with Purple-throated Carib hummingbirds: nectar, visitation, and phenological study of heliconias from the Caribbean.
Plant-pollinator interactions such as the heliconia-hummingbird interactions provide one of the best examples of co-evolutionary interactions in nature. Only two native heliconias (H.bihai and H.caribaea) are known from the Lesser Antilles (Caribbean) and they have been proposed to have an adaptive interaction with their native hummingbird pollinators. In particular, dimorphic Purple-throated Carib hummingbirds (Eulampis jugularis) have been proposed to show a sex-specific adaptation to the two native Heliconia spp. where male and female Purple-throated Caribs visit H.caribaea while only female Purple-throated Caribs visit H.bihai. The male Purple-throated Caribs are territorial in nature and defend patches of H.caribaea against conspecific males and allow a female to feed in exchange of sex. The females however visit the two heliconias by trap-lining and rarely display territorial behavior on H.bihai against conspecific birds. Here, we provide further evidence on geographic variation in this interaction between islands and evaluate the role of heliconias in driving this sex-specific interaction across the archipelago. We looked at heliconia mating system, nectar biology, plant phenology, and plant selectivity and compared and contrasted the interactions within and between islands. All studies were carried out on the islands of St.Kitts, Dominica and St.Vincent. Our results show that though the plants are partially self-compatible outcrossing is favored in H.bihai and H.caribaea. Partial self-compatibility has been reported in other Heliconia sp. and could be a mechanism for ‘fail-safe pollination’. We show that the hummingbirds in the three Lesser Antillean islands are indeed highly dependent on heliconias as their main food source however, conspecific competition within the pollinators to the native heliconias varies between different islands leading to a geographic variation in intensity of adaptive interaction between islands. We propose that the total available nectar, plant phenology and bird mating system could have favored the evolution of highly sex-specific heliconia-hummingbird interaction within each island.
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1 - George Washington University, Department of Biological Sciences, Lisner Hall 340, 2023 G Street, NW, Washington, DC, 20052, USA
2 - Smithsonian, Botany, PO Box 37012, Washington, D.C, 20013-7012, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Ontario/Hilton
Date: Monday, July 9th, 2007
Time: 11:30 AM