TY - JOUR

T1 - Arbuscular mycorrhizal fungi promote coexistence and niche divergence of sympatric palm species on a remote oceanic island

AU - Osborne, Owen G

AU - De-Kayne, Rishi

AU - Bidartondo, Martin I

AU - Hutton, Ian

AU - Baker, William J

AU - Turnbull, Colin G N

AU - Savolainen, Vincent

N1 - © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

PY - 2018/2/1

Y1 - 2018/2/1

N2 - Microbes can have profound effects on their hosts, driving natural selection, promoting speciation and determining species distributions. However, soil-dwelling microbes are rarely investigated as drivers of evolutionary change in plants. We used metabarcoding and experimental manipulation of soil microbiomes to investigate the impact of soil and root microbes in a well-known case of sympatric speciation, the Howea palms of Lord Howe Island (Australia). Whereas H. forsteriana can grow on both calcareous and volcanic soils, H. belmoreana is restricted to, but more successful on, volcanic soil, indicating a trade-off in adaptation to the two soil types. We suggest a novel explanation for this trade-off. Arbuscular mycorrhizal fungi (AMF) are significantly depleted in H. forsteriana on volcanic soil, relative to both H. belmoreana on volcanic soil and H. forsteriana on calcareous soil. This is mirrored by the results of survival experiments, where the sterilization of natural soil reduces Howea fitness in every soil-species combination except H. forsteriana on volcanic soil. Furthermore, AMF-associated genes exhibit evidence of divergent selection between Howea species. These results show a mechanism by which divergent adaptation can have knock-on effects on host-microbe interactions, thereby reducing interspecific competition and promoting the coexistence of plant sister species.

AB - Microbes can have profound effects on their hosts, driving natural selection, promoting speciation and determining species distributions. However, soil-dwelling microbes are rarely investigated as drivers of evolutionary change in plants. We used metabarcoding and experimental manipulation of soil microbiomes to investigate the impact of soil and root microbes in a well-known case of sympatric speciation, the Howea palms of Lord Howe Island (Australia). Whereas H. forsteriana can grow on both calcareous and volcanic soils, H. belmoreana is restricted to, but more successful on, volcanic soil, indicating a trade-off in adaptation to the two soil types. We suggest a novel explanation for this trade-off. Arbuscular mycorrhizal fungi (AMF) are significantly depleted in H. forsteriana on volcanic soil, relative to both H. belmoreana on volcanic soil and H. forsteriana on calcareous soil. This is mirrored by the results of survival experiments, where the sterilization of natural soil reduces Howea fitness in every soil-species combination except H. forsteriana on volcanic soil. Furthermore, AMF-associated genes exhibit evidence of divergent selection between Howea species. These results show a mechanism by which divergent adaptation can have knock-on effects on host-microbe interactions, thereby reducing interspecific competition and promoting the coexistence of plant sister species.

KW - Arecaceae/microbiology

KW - Biodiversity

KW - DNA Barcoding, Taxonomic

KW - Ecosystem

KW - Geography

KW - Germination

KW - Islands

KW - Mycorrhizae/growth & development

KW - Oceans and Seas

KW - Principal Component Analysis

KW - Seedlings/physiology

KW - Soil Microbiology

KW - Species Specificity

KW - Sympatry/physiology

U2 - 10.1111/nph.14850

DO - 10.1111/nph.14850

M3 - Article

C2 - 29034978

VL - 217

SP - 1254

EP - 1266

JO - New Phytologist

JF - New Phytologist

SN - 0028-646X

IS - 3

ER -