OOS 2-4 - Mycorrhizal types influence global island biogeography: invasion risks and effects of plant naturalizations

Monday, August 15, 2022

2:15 PM – 2:30 PM EDT

Location: 520D

Presenting Author(s)

CD

Camille Delavaux

ETH Zurich, Switzerland

Co-author(s)

PW

Patrick Weigelt

University of Gottingen
WD

Wayne Dawson

University of Durham
FE

Franz Essl

University Vienna
MV

Mark Van Kleunen

University of Konstanz, Germany
CK

Christian König

University of Gottingen
JP

Jan Perg

Czech Academy of Sciences
PP

Petr Pyšek

Czech Academy of Sciences
AS

Anke Stein

University of Konstanz
MW

Martin Winter

German Centre for Integrative Biodiversity Research
AT

Amanda Taylor

University of Gottingen
PS

Peggy A. Schultz

University of Kansas
RW

Robert J. Whittaker

University of Oxford
HK

Hogler Kreft

University of Gottingen
JB

James D. Bever, PhD

Senior Scientist
The University of Kansas, United States

Background/Question/Methods
Although island plant biogeography has historically focused on abiotic drivers, plant colonization on islands could also be limited by biotic drivers, such as the absence of symbionts. Most plants form symbioses with mycorrhizal fungi, whose limited dispersal to islands could act as a colonization filter for plants. Many plant species are highly dependent on mycorrhizal fungi, however, these fungi disperse independently of their plant hosts and therefore the absence of mycorrhizal fungi can limit the colonization of mycorrhizal plant species. In addition, plant colonization may be differentially limited by mycorrhizal types, being more limited by mycorrhizal fungi with limited dispersal ability. Here, we test for differences in the strength of the mycorrhizal filter across plant species associating with the three major mycorrhizal types: arbuscular mycorrhizal (AM) fungi, the most common type of mycorrhizae, ectomycorrhizal and ericoid mycorrhizal (EEM) fungi, and orchid mycorrhizal (ORC) fungi. We tested for such differential island colonization across mycorrhizal types within angiosperm floras worldwide, first within native and then within invasion floras.

Results/Conclusions
We found evidence that arbuscular mycorrhizal (AM) plants experience a stronger mycorrhizal filter than other mycorrhizal or non-mycorrhizal plant species, with decreased proportions of native AM plant species on islands relative to mainlands. This effect increased with island isolation, particularly for non-endemic plant species. We further found evidence of humans overcoming the initial mycorrhizal filter, presumably due to co-introduction of plants with their symbionts. Naturalized floras showed higher proportions of AM plant species than native floras, a pattern that increased with increasing isolation and land-use intensity. This work provides evidence that mycorrhizal fungal symbionts shape plant colonization of islands, subsequent diversification, and invasion risks. Importantly, this work shows that biotic interactions between plants and soil mutualists determine global plant biogeography, shifting the longstanding abiotic centric perspective in island biogeography to include plant-associated mutualists.