DOI: 10.5061/dryad.fb96h
title: Data from: Natural habitat loss and exotic plants reduce the functional diversity of flower visitors in a heterogeneous subtropical landscape

description: 1. Functional diversity (FD) of pollinators can increase plant
 reproductive output and the stability of plant-pollinator communities.
 Yet, in times of worldwide pollinator declines, effects of global change
 on pollinator FD remain poorly understood. Loss of natural habitat and
 exotic plant invasions are two major drivers of global change that
 particularly threaten pollinator diversity. 2. In a subtropical South
 African landscape, we investigated changes in the FD of flower visitor
 assemblages on native and exotic plants along gradients of natural habitat
 loss and relative abundance of exotic plants. We used a dataset of 1434
 flower visitor individuals sampled on 131 focal plants and calculated the
 FD in three flower visitor traits that are strongly related to
 plant-flower visitor interactions and pollination processes: proboscis
 length, proboscis diameter and body length. 3. Multivariate FD of flower
 visitors decreased with both increasing natural habitat loss and relative
 exotic abundance. Importantly, changes in FD went beyond those in flower
 visitor richness. Furthermore, flower visitor richness was not related to
 either natural habitat loss or relative exotic abundance. Loss in
 multivariate FD seemed to be mediated by complementary reductions of FD in
 proboscis length with natural habitat loss and of FD in body length with
 both global change drivers. Correspondingly, we recorded lower abundances
 of long-tongued flower visitors with natural habitat loss and reduced
 variance in body size with both drivers. In contrast, FD in proboscis
 diameter was unaffected by either driver. All effects of the two global
 change drivers were non-interactive. 4. Our results show that both natural
 habitat loss and exotic plants negatively affect flower visitor FD, which
 may imperil pollination of specialised plant species in degraded habitats.
 In contrast, flower visitor richness may not cover all facets of flower
 visitor FD that are relevant to pollination processes, and here future
 studies are needed. Distinct responses of visitor traits to the two
 drivers suggest limited options to infer relations of one trait to
 another. Finally, additive effects of natural habitat loss and exotic
 plant invasions highlight the need to consider multiple drivers of global
 change when investigating ecosystem processes at a community scale.
description: Functional traits of
 flower visitors and plants and plant-flower visitor interactions across 17
 study sites in a South African landscapeData on functional
 traits of flower visitors and plants and on plant-flower visitor
 interactions across 17 study sites in a South African landscape. Study
 sites differed in their local degree of natural habitat loss and relative
 floral abundance of exotic plant species. Functional traits of flower
 visitors were used to calculate changes in the functional diversity of
 flower visitor communities with increasing amount of habitat loss and
 relative abundance of exotic plants. See the read me file for more
 detailed information.Grass_data.zip