Pollination of the heterostylous Galápagos native, Cordia lutea (Boraginaceae)

The hypothesis of this study was that in the Galápagos Islands, fruit and seed set via nocturnal pollination would exceed that of diurnal pollination due to greater insect activity at night typical of hot, arid regions. Cordia lutea, a heterostylous member of the Galápagos flora, was submitted to po...

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Bibliographic Details
Published in:	Plant systematics and evolution 2012-03, Vol.298 (3), p.569-579
Main Author:	McMullen, Conley K
Format:	Article
Language:	eng
Subjects:	Arid regions Arid zones Autogamy Bees Biomedical and Life Sciences Butterflies & moths carpenter bees Cordia Cross-pollination Diurnal Flora Flowers Fruit set Fruits Insect pollination Insects islands Life Sciences Low level Moths Nectar nectar robbing Nocturnal open pollination Original Article Plant Anatomy/Development Plant Ecology Plant reproduction Plant Sciences Plant Systematics/Taxonomy/Biogeography Plants Pollen Pollinating insects Pollination Pollinators Seed set Self-fertilization
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Summary:	The hypothesis of this study was that in the Galápagos Islands, fruit and seed set via nocturnal pollination would exceed that of diurnal pollination due to greater insect activity at night typical of hot, arid regions. Cordia lutea, a heterostylous member of the Galápagos flora, was submitted to pollination experiments, visitor observations, nectar sampling, pollen transfer studies, pollen-ovule ratio studies, and pollen measurements. Flowers set fruit and seed via open pollination, autonomous autogamy, facilitated autogamy, facilitated cross-pollination, diurnal pollination, and nocturnal pollination. There was a significant difference in fruit set between flowers experiencing legitimate cross-pollinations (pin × thrum) and those experiencing all other pollination treatments except facilitated autogamy. There was no significant difference in seed set among any of the treatments, but there was a trend toward greater seed set for flowers experiencing open-pollination, legitimate cross-pollination, and nocturnal pollination. There was no significant difference in fruit set or seed set between flowers experiencing diurnal pollination and nocturnal pollination, although there was a trend toward greater seed set resulting from nocturnal pollination. Carpenter bees were the most effective diurnal pollinators, whereas moths were the most effective nocturnal pollinators. Of the two, moths are more efficient at transporting pollen from plant to plant. Results indicate that an overall low productivity of this species is due to pollen limitation exacerbated by nectar robbing. Cordia lutea exhibits a mixed mating system, producing a relatively low level of fruits through a combination of self- and cross-pollination, facilitated by the relatively few insects that are available.
ISSN:	0378-2697 1615-6110