Unpredictable soil conditions affect the prevalence of a microbial symbiosis

Abstract

The evolution of symbiotic interactions may be affected by unpredictable conditions. However, a link between prevalence of symbiosis and these conditions has not been widely demonstrated. We test for these associations usingDictyostelium discoideumsocial amoebae and their bacterial symbionts.D. discoideumare host to endosymbiotic bacteria from three taxa:Paraburkholderia,Amoebophilusand Chlamydiae. Three species of facultativeParaburkholderiasymbionts are the best studied and give hosts the ability to carry food bacteria through the dispersal stage to new environments.Amoebophilusand Chlamydiae are obligate endosymbionts with no measurable impact on host fitness. We test whether the frequency of both single infections and coinfections of these symbionts are associated with the unpredictability of their soil environments by using symbiont presence-absence data from soil isolates from 21 locations across the eastern United States. We find that thatAmoebophilusand Chlamydiae obligate endosymbionts and coinfections are not associated with any of our mean measures, but that unpredictable precipitation can promote or hinder symbiosis depending on the species ofParaburkholderiasymbiont.

Complex third-party effects in theDictyostelium-Paraburkholderiasymbiosis: prey bacteria that are eaten, carried, or left behind

“…We speculate that carrying more prey in prey-poor contexts may represent cooperation between hosts and symbionts that allows the symbiosis to persist over repeated harsh environments. Such harsh conditions are potentially an important force shaping cooperation in this (Scott et al ., 2022, 2023b) and other symbioses (Henry et al ., 2021; Veresoglou et al ., 2021; Cornwallis et al ., 2023). These studies in symbiotic systems complement research on the role of harsh environments in the evolution of cooperation that has been focused on interactions between members of the same species (Kennedy et al ., 2018), most commonly in cooperatively breeding birds (Cornwallis et al ., 2017; Griesser et al ., 2017; Capilla-Lasheras et al ., 2021).…”

Unpredictable soil conditions can affect the prevalence of a microbial symbiosis

“…Portions of the text in this manuscript were previously published as a preprint ( Scott et al, 2023b ) and as part of a thesis ( Scott, 2023 ).…”

“…The evolution of cooperation varies with ecological unpredictability ( Scott, 2023 ; Scott et al, 2023b ). For example, the prevalence of cooperative breeding in birds is associated with unpredictable environmental conditions ( Jetz & Rubenstein, 2011 ; Griesser et al, 2017 ).…”