Will climate change increase hybridization risk between potential plant invaders and their congeners in Europe?

Günther Klonner,Marten Winter,Jan Pergl,Patrick Weigelt,Franz Essl,Wayne Dawson,Petr Pyšek,Holger Kreft,Emily Haeuser,Marta Carboni,Oliver Bossdorf,Johannes Wessely,Wilfried Thuiller,Dietmar Moser,Iwona Dullinger,Andreas Gattringer,Stefan Dullinger,Mark Van Kleunen

doi:10.1111/ddi.12578

Abstract

AimInterspecific hybridization can promote invasiveness of alien species. In many regions of the world, public and domestic gardens contain a huge pool of non‐native plants. Climate change may relax constraints on their naturalization and hence facilitate hybridization with related species in the resident flora. Here, we evaluate this possible increase in hybridization risk by predicting changes in the overlap of climatically suitable ranges between a set of garden plants and their congeners in the resident flora.LocationEurope.MethodsFrom the pool of alien garden plants, we selected those which (1) are not naturalized in Europe, but established outside their native range elsewhere in the world; (2) belong to a genus where interspecific hybridization has been previously reported; and (3) have congeners in the native and naturalized flora of Europe. For the resulting set of 34 alien ornamentals as well as for 173 of their European congeners, we fitted species distribution models and projected suitable ranges under the current climate and three future climate scenarios. Changes in range overlap between garden plants and congeners were then assessed by means of the true skill statistic.ResultsProjections suggest that under a warming climate, suitable ranges of garden plants will increase, on average, while those of their congeners will remain constant or shrink, at least under the more severe climate scenarios. The mean overlap in ranges among congeners of the two groups will decrease. Variation among genera is pronounced; however, and for some congeners, range overlap is predicted to increase significantly.Main conclusionsAveraged across all modelled species, our results do not indicate that hybrids between potential future invaders and resident species will emerge more frequently in Europe when climate warms. These average trends do not preclude, however, that hybridization risk may considerably increase in particular genera.

Highlights

Biological invasions are an important component of global environmental change and may have severe ecological as well as economic impacts (Bellard, Cassey, & Blackburn, 2016; Vilà et al, 2011)
We studied a group of 783 alien ornamental plants not yet naturalized in Europe, but established outside their native range elsewhere in the world, as identified in Dullinger et al (2016)
When overlap is measured as the number of 10′ × 10′ cells that are climatically suitable to both the garden plants and their congeners, the results suggest that a warmer climate will not change the size of overlapping ranges in a statistically significant way in any of the scenarios (Figure 1b, see Table S4)

Summary

Introduction

Biological invasions are an important component of global environmental change and may have severe ecological as well as economic impacts (Bellard, Cassey, & Blackburn, 2016; Vilà et al, 2011). There are, a number of factors known to facilitate invasions such as early reproduction, rapid growth rate, efficient long- distance dispersal or specific trait profiles which are complementary to those of the resident biota (Buhk & Thielsch, 2015; Carboni et al, 2016; van Kleunen, Weber, & Fischer, 2010; Küster, Kühn, Bruelheide, & Klotz, 2008; Pyšek et al, 2015). Apart from these factors, interspecific hybridization has been assumed to foster invasions since a seminal paper of Ellstrand and Schierenbeck (2000). Heterosis effects may be maintained especially when hybridization is accompanied by allopolyploidization and/or a shift to apomictic reproduction, which sustain heterozygosity

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