Opportunistic pollination by birds and lizards in the Canary Islands

Abstract

The consequences of mutualistic plant-animal interactions on plant reproductive success depend on the animal’s effectiveness and the context in which the mutualism occurs. The present thesis is about the interplay between these two aspects in the mutualism of pollination. We try to meet the challenge with a particular group of pollinators, opportunistic nectar-feeding vertebrates, in a particular context, oceanic islands. Due to their intrinsic ecological conditions, oceanic islands favour the appearance of depauperate and disharmonic assemblages of opportunistic pollinators, whose effectiveness and level of context dependence may differ significantly from those of continental systems. In the concrete case of the Canary Islands, passerine birds and lacertid lizards are frequent floral visitors of native flora, but their pollination ecology has remained almost unknown. For this reason, the present thesis follows a dual objective: first to experimentally demonstrate the effectiveness of birds and lizards as pollinators (chapters 2-3) and analyse the potential differences between both functional groups (chapter 4), to then understand how their benefits on plant fitness vary under the presence of antagonists (chapters 5-6).