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Abstract Detail


Sakishima, Tomoko [1], Stacy, Elizabeth [1].

Plant-plant interaction in early- vs. late-successional varieties of the Hawaiian landscape-dominant tree, Metrosideros polymorpha.

Plant-plant interactions play an important role in assembling plant communities. A growing body of research suggests that some plants have the ability to recognize how genetically related they are to neighboring plants and can behave differently as a result. When growing alongside close relatives, some species decrease their growth through cooperation or through competition, which is expected to increase with phenotypic similarity. Thus, plant interactions with kin can lead to increased or decreased fitness. On the other hand, between genetically distant neighbors, niches are expected to be less overlapped, and this should lead to lower competition and higher fitness. Additionally, mycorrhizal fungi may have complex effects on plant interactions through their connection with plant roots. This study compares the nature of plant-plant interactions between early- and late-successional varieties of Hawaiian trees, Metrosideros polymorpha vars. incana and glaberrima, that differ in population density and the abundance of mycorrhizal fungi. Metrosideros polymorpha var. incana forms low-density populations on young lava flows where it establishes in cracks with limited soil and associated fungal communities. Metrosideros polymorpha var. glaberrima is a late-successional variety that dominates wet forests on deep, well-formed soils with greater mycorrhizal abundance. We predict that seedlings will respond (grow) differently to genetically different neighbors and that the pattern of response will differ between the varieties and in the presence/absence of mycorrhizae. Specifically, we expect to observe stronger cooperation and more positive effects of mycorrhizae in seedlings of late-successional var. glaberrima relative to early-successional var. incana. To test these predictions, growth rates of focal seedlings are being measured under three treatments of neighbor relatedness (a sibling, a different population of the same variety, and the opposite variety) with and without mycorrhizal fungi. Quantification of hyphal density will reveal the relative roles of cooperation versus competition; cooperating seedlings are expected to increase the flow of photosynthesis-derived carbohydrates to their mycorrhizal symbionts, thus increasing hyphal growth. Results to date show that for both varieties, seedling growth is suppressed in the presence of sibling neighbors and promoted in the presence of seedlings of the opposite variety. The pattern of seedling growth across treatments is similar with and without mycorrhizal fungi, suggesting that mycorrhizae may not affect neighbor interactions in M. polymorpha. Quantification of mycorrhizal hyphal density is underway. Results of this study will improve our understanding of plant-plant interactions within Hawaii’s landscape-dominant tree, which may be applied to forest restoration practices.

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1 - University of Nevada, Las Vegas, School of Life Sciences , 4505 S Maryland Pkwy, Las Vegas, NV, 89154, USA

none specified

Presentation Type: Oral Paper
Session: ECO8, Ecology: Interactions
Location: /
Date: Friday, July 23rd, 2021
Time: 10:30 AM(EDT)
Number: ECO8003
Abstract ID:1081
Candidate for Awards:None


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