The Direct and Ecological Costs of an Ant-Plant Symbiosis

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Submitted July 12, 2011; Accepted February 3, 2012; Electronically published April 25, 2012 Online enhancement: appendix. Dryad data: http://dx.doi.org/10.5061/dryad.144v45c6. The University of Chicago Press andabstract: How strong is selection for cheating in mutualisms? The answer depends on the type and magnitude of the costs of the mutualism. Here we investigated the direct and ecological costs of plant defense by ants in the association between Cordia nodosa, a myrmecophytic plant, and Allomerus octoarticulatus, a phytoecious ant. Cordia nodosa trees produce food and housing to reward ants that protect them against herbivores. For nearly 1 year, we manipulated the presence of A. octoarticulatus ants and most insect herbivores on C. nodosa in a full-factorial experiment. Ants increased plant growth when herbivores were present but decreased plant growth when herbivores were absent, indicating that hosting ants can be costly to plants. However, we did not detect a cost to ant colonies of defending host plants against herbivores. Although this asymmetry in costs suggests that the plants may be under stronger selection than the ants to cheat by withholding investment in their partner, the costs to C. nodosa are probably at least partly ecological, arising because ants tend scale insects on their host plants. We argue that ecological costs should favor resistance or traits other than cheating and thus that neither partner may face much temptation to cheat.

Caterpillars lack a resident gut microbiome

“…There are costs to engaging in mutualisms (e.g., refs. [77][78][79], and in a gut microbiome context one cost includes nutrient competition between host and microbes (80). A high availability of food allows caterpillars to "skim the cream" (62), assimilating simple nutrients that might otherwise be used by gut microbes and excreting recalcitrant material.…”

Direct and Pollinator-Mediated Effects of Herbivory on Strawberry and the Potential for Improved Resistance

“…Herbivores are known to affect plant reproduction both directly and indirectly. Direct effects of herbivory result from consumption of plant tissues which, in turn, may cause resource limitation (Strauss et al, 2002). In addition, given the intrinsic link between plant reproduction and defense mechanisms, direct effects of herbivory may also be mediated via trade-offs between investing in reproduction or investing in defenses (Herms and Mattson, 1992; Strauss et al, 2002).…”

Neotropical ant-plant Triplaris americana attracts Pseudomyrmex mordax ant queens during seedling stages

“…In ant–plant mutualisms, nesting space is a limiting factor for ant colony size (Fonseca 1993) and colony size correlates with defense effectiveness (Heil and McKey 2003; Brouat and McKey 2001; Frederickson et al 2012). However, even when myrmecophytes are at the seedling stage, it has been shown that the first hatched workers of the incipient colony patrol the plant (Brouat and McKey 2000; Moog et al 2005).…”