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Lookup NU author(s): Professor Pip MooreORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2023 The Authors. Ecography published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos. Symbionts tend to be aggregated on their hosts, such that few hosts harbor the majority of symbionts. This ubiquitous pattern can result from stochastic processes, but aggregation patterns may also depend on the type of host–symbiont interaction, along with traits that affect host exposure and susceptibility to symbionts. Untangling how aggregation patterns both within and among populations depend on stochastic processes, interaction type and host traits remains an outstanding challenge. Here, we address this challenge by using null models to compare aggregation patterns in a neutral system of Balanomorpha barnacles attached to patellid limpets and a host–parasite system of Gyrodactylus spp. monogeneans and their Trinidadian guppy Poecilia reticulata hosts. We first used a model to predict patterns of symbiont–host aggregation due to random partitioning of symbionts to hosts. This null model accurately predicted the aggregation of barnacles on limpets, but the degree of aggregation varied across 303 quadrats. Quadrats with larger limpets had less aggregated barnacles, whereas aggregation increased with variation in limpet size. Across 84 guppy populations, Gyrodactylus spp. parasites were significantly less aggregated than predicted by the null model. As in the neutral limpet–barnacle system, aggregation decreased with mean host size. Parasites were significantly less aggregated on males than females because male guppies tended to have higher prevalence and lower parasite burdens than predicted by the null model. Together, these results suggest stochastic processes can explain aggregation patterns in neutral but not parasitic systems, though in both systems host traits affect aggregation patterns. Because the distribution of symbionts on hosts can affect symbiont evolution via intraspecific interactions, and host behavior and evolution via host–symbiont interactions, identifying the drivers of aggregation enriches our understanding of host–symbiont interactions.
Author(s): Clark DR, Young KA, Kitzes J, Moore PJ, Evans AJ, Stephenson JF
Publication type: Article
Publication status: Published
Journal: Ecography
Year: 2023
Pages: Epub ahead of print
Online publication date: 26/10/2023
Acceptance date: 07/09/2023
Date deposited: 08/11/2023
ISSN (print): 0906-7590
ISSN (electronic): 1600-0587
Publisher: John Wiley and Sons Inc.
URL: https://doi.org/10.1111/ecog.06858
DOI: 10.1111/ecog.06858
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