Abstract Detail

Tropical Biology

Sur, Gary [1], Zahn, Geoffrey [2], Stacy, Elizabeth [3].

Evaluating Host-Taxon, Environment, and Distance Effects on Leaf Fungal Endophytes in Hawaiian Metrosideros.

Fungal endophytes (FEs) are fungi living inside plant tissues that may contribute to host-plant fitness.  Insight into how FEs are distributed across space and host-plant taxa is a first step to understanding possible functional relationships between FEs and their hosts.  Using 8 taxa of Metrosideros (Myrtaceae) on the Hawaiian Island of O‘ahu (M. rugosa, M. tremuloides and 6 varieties or races of M. polymorpha), we compared the relative importance of host taxon, elevation (environment), and geographic distance on FE composition and diversity.  Leaf samples were collected from trees along four individual elevation gradients (sites), including 4 Metrosideros taxa/site: two sympatric taxa at high elevation (wetter and cooler conditions) and two sympatric taxa at low elevation (drier and warmer conditions) (11 trees/taxon/gradient, n = 176 trees).  After extracting DNA from surface-sterilized leaves, completing ITS-1 region amplification of fungal DNA, metagenomic sequencing, and sequence-quality filtering, the remaining samples (n = 113 trees) yielded 1,637 unique fungal sequences: 5 phyla, 20 classes, 58 orders, 133 families, 223 genera, and 200 species.  While variation in FE diversity was significantly explained by Metrosideros taxon, site, and geographic distance, there was considerable overlap in FE communities among host taxa and among sites.  Among the 8 host taxa, the tree, M. polymorpha var. glaberrima (the only Metrosideros taxon with an archipelago-wide distribution) and mat plant, M. polymorpha race prostrata, had the highest FE Shannon diversities, consistent with high FE diversity in widespread taxa and possible FE transmission from soil.  Evidence for FE host-specificity was weak and restricted to 700-1,000 m above sea level.  Although the FE communities did not vary with environment (elevation), the elevation range of Metrosideros on O‘ahu (476-1,233 m) may be too narrow for the detection of environmental effects on FE composition.  Lastly, we detected significant isolation-by-distance effects on both alpha-diversity and beta-diversity of FE communities.  Our results suggest that among O‘ahu Metrosideros, there is modest variation in leaf FE composition and diversity associated with host taxonomic effects and distance between trees and very little associated with environmental variation across the island`s elevation gradient.

1 - University of Hawaii at Hilo, 200 W Kawili St, Hilo, HI, 96720, USA
2 - Utah Valley University, 800 W. University Pkwy, Orem, UT, 84058, USA
3 - University Of Nevada Las Vegas, School of Life Sciences, Las Vegas, NV, 89154, USA

fungal endophytes
Metrosideros (Myrtaceae)
elevational gradients
horizontal transmission
host specificity
long distance dispersal

Presentation Type: Poster
Session: P, Tropical Biology Posters
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 5:00 PM Time and date to be determined
Number: PTB005
Abstract ID:633
Candidate for Awards:None

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