Colonisation and competition dynamics can explain incomplete sterilisation parasitism in ant–plant symbioses. (11th August 2014)

• Record Type: Journal Article
• Authors: Tarnita, Corina E.; Palmer, Todd M.; Pringle, Robert M.; Bourke, Andrew
• Is Part Of: Ecology letters. Volume 17:Number 10(2014:Oct.)
• Page Start: 1290
• Page End: 1298
• Publication Date: 2014-08-11
• Subjects: Ecology -- Periodicals; 577
• DOI: 10.1111/ele.12336
• Languages: English
• ISSNs: 1461-023X

Abstract

<abstract abstract-type="main" id="ele12336-abs-0001"> <title>Abstract</title> <p>Sterilisation of parasites prevents host reproduction, thereby diverting host resources to their own benefit. Previous theory predicts that parasites should evolve maximum virulence, yet hosts are often incompletely sterilised. Whereas prior attempts to resolve this paradox have sought evolutionary explanations, we present theory and experiments showing that incomplete sterilisation can arise from ecologically driven fluctuations in parasite load. The African ant–plant <italic>Acacia drepanolobium</italic> reproduced more when occupied by small colonies of the sterilising symbiont <italic>Crematogaster nigriceps</italic>. In nature, small colonies result from interference competition between ant colonies; these territorial conflicts thus provide intermittent windows of opportunity for host reproduction. Our mean‐field model shows that numerical insufficiency of parasites can produce partial sterilisation of host populations, creating the appearance of reduced virulence even if ants have evolved to sterilise completely. This general framework helps explain both the apparent ubiquity of partial sterilisation parasitism and the ability of these symbiotic associations to persist.</p> </abstract>