Pollination by New Zealand Geckos

Abstract

The New Zealand pollination system is believed to be generalised and entomophilic, while the visitation of lizards to flowers has generally been considered as nectar thieving. Observations of New Zealand lizard-plant interactions are limited and their relative importance and effectiveness as potential pollinators was unknown. The existence and the effectiveness of the lizard genera Hoplodactylus and Naultinus (Gekkonidae) as pollinators of Metrosideros excelsa (Myrtaceae) and Phormium tenax (Hemerocallidaceae) was assessed using several lines of evidence. On Otata Island, a regenerating native ecosystem, flower visitor observations were conducted. Exotic ants, Hoplodactylus maculatus and native bees were the main flower visitors to M. excelsa. The standing nectar crop decreased at night time when the nocturnal H. maculatus visited. Hoplodactylus maculatus also consumed Macropiper excelsum (Piperaceae) fruit but this interaction may be disrupted by exotic bird competition. Pollinator effectiveness was assessed with pollinator exclusion experiments. In the field experiment there was very weak evidence that H. maculatus were having an effect on pollination of M. excelsa. Laboratory experiments provided very strong evidence that these lizards could self-pollinate Metrosideros collina ‘Tahiti’ flowers. In a naturalised laboratory setting components of the pollinator efficiency of H. maculatus, H. duvaucelii, H. granulatus and N. elegans elegans were measured. The geckos collected large amounts of pollen, transported it for many hours and deposited it on M. excelsa or P. tenax stigmas effectively. Thus New Zealand geckos can physically function as a pollinator vector. The importance of these findings provides further understanding on the ecology of lizards, the New Zealand pollination system. New Zealand geckos are not necessarily nectar thieves and can be pollinators. With the decline in range and abundance of New Zealand lizards and the lack of data on lizard-flower interactions a conservation concern is raised about the state of pollination interactions.