title: Decreasing water availability across the globe improves the effectiveness of protective ant-plant mutualisms: a meta-analysis.
abstract: Abiotic conditions can increase the costs of services and/or the benefits of rewards provided by mutualistic partners. Consequently, in some situations, the outcome of mutualisms can move from beneficial to detrimental for at least one partner. In the case of protective mutualisms between ant bodyguards and plants bearing extrafloral nectaries (EFNs), plants from arid environments face a trade-off between EFN production and maintenance and water and carbon economy. This trade-off may increase EFN costs and decrease their value as a defensive strategy to plants in such environments. Despite this, the presence of EFNs is an ubiquitous trait in plants from arid environments, suggesting that they provide greater benefits to plants in these environments to compensate for their higher costs. We used a meta-analysis to investigate if such benefits do increase with decreasing water availability and the possible underlying causes (such as ant behaviour or ant diversity). As predicted, ant effect on EFN plants performance increased as mean annual precipitation decreased. We also found that the frequency of dominant ants on EFN plants increased in drier areas. Due to the more aggressive behaviour of dominant ants, we suggest that they represent an important factor shaping the adaptive value of EFNs to plants in arid environments.
authors: Programa de pós-graduação em Zoologia, Universidade Estadual de Feira de Santana, Feira de Santana, 44036-900, Brazil.|Departamento de Ciências Biológicas, Universidade Federal de São Paulo, 09972-270, Diadema, Brazil.
authors: Laura C
authors: http://orcid.org/0000-0003-1570-8901
authors: LC
authors: Leal
authors: Programa de pós-graduação em Zoologia, Universidade Estadual de Feira de Santana, Feira de Santana, 44036-900, Brazil.|Laboratório de Entomologia, Universidade Estadual de Feira de Santana, Feira de Santana, 44036-900, Brazil.
authors: Paulo E C
authors: PEC
authors: Peixoto
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology*; D003889:Desert Climate; D057048:Plant Nectar / Q000378:metabolism; D010944:Plants / Q000469:parasitology*; D013559:Symbiosis; D014867:Water
chemical_list: D057048:Plant Nectar; D014867:Water
keywords: anti-herbivore defence; coevolutionary mosaics; context-dependence; extrafloral nectar; facultative mutualism; partner identity