title: No difference in the competitive ability of introduced and native Trifolium provenances when grown with soil biota from their introduced and native ranges.
abstract: The evolution of increased competitive ability (EICA) hypothesis could explain why some introduced plant species perform better outside their native ranges. The EICA hypothesis proposes that introduced plants escape specialist pathogens or herbivores leading to selection for resources to be reallocated away from defence and towards greater competitive ability. We tested the hypothesis that escape from soil-borne enemies has led to increased competitive ability in three non-agriculturalTrifolium(Fabaceae) species native to Europe that were introduced to New Zealand in the 19th century.Trifoliumperformance is intimately tied to rhizosphere biota. Thus, we grew plants from one introduced (New Zealand) and two native (Spain and the UK) provenances for each of three species in pots inoculated with soil microbiota collected from the rhizosphere beneath conspecifics in the introduced and native ranges. Plants were grown singly and in competition with conspecifics from a different provenance in order to compare competitive ability in the presence of different microbial communities. In contrast to the predictions of the EICA hypothesis, we found no difference in the competitive ability of introduced and native provenances when grown with soil microbiota from either the native or introduced range. Although plants from introduced provenances of two species grew more slowly than native provenances in native-range soils, as predicted by the EICA hypothesis, plants from the introduced provenance were no less competitive than native conspecifics. Overall, the growth rate of plants grown singly was a poor predictor of their competitive ability, highlighting the importance of directly quantifying plant performance in competitive scenarios, rather than relying on surrogate measures such as growth rate.
authors.affiliation: Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand natasha.shelby17@gmail.com.
authors.forename: Natasha
authors.initials: N
authors.lastname: Shelby
authors.affiliation: Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand.
authors.forename: Philip E
authors.initials: PE
authors.lastname: Hulme
authors.affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands Laboratory of Nematology, Wageningen University, PO Box 8123, 6700 ES Wageningen, The Netherlands.
authors.forename: Wim H
authors.initials: WH
authors.lastname: van der Putten
authors.affiliation: Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: McGinn
authors.affiliation: Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands.
authors.forename: Carolin
authors.initials: C
authors.lastname: Weser
authors.affiliation: Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Duncan
keywords: Alien; competition; enemy-release; exotic; invasive; rhizosphere microbiota; soil biota; weed