Abstract:
Coloured nectar is a rare phenomenon best known from islands and
insular habitats. Islands are also known for lizard pollination, where
coloured nectar potentially acts as a visual cue to attract pollinators,
advertising the sweet reward. However, nectar may also contain secondary
metabolites with toxic or deterrent effects. The aim of this study was
to determine which factors are important as artificial nectar choice determinants
to the Madagascar giant day gecko, Phelsuma grandis, an island
pollinator: artificial nectar colour, artificial nectar colour saturation, artificial
nectar conspicuousness and/or the presence of the alkaloid nicotine.
Coloured artificial nectar and the darkest artificial nectar colour
saturation were found to be important visual cues for the geckos, while
the contrast between artificial nectar and petal colour was not. Geckos
were deterred only by high nicotine concentrations (1000 lM in 0.63 M
sucrose) and may even prefer low nicotine concentrations to sucroseonly
solutions. Given their overall fondness for sugar solutions, Madagascar
giant day geckos are likely to be important pollinators of Malagasy
plant species that produce enough nectar to attract them, and plants with
coloured nectar and/or secondary metabolites may have evolved those
traits to attract the geckos in particular.
