Effects of human disturbance and climate change on myrmecochory in Brazilian caatinga

Inara R. Leal, Laura C. Leal, Fernanda M.P. Oliveira, Gabriela B. Arcoverde, Alan N. Andersen

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

Abstract

Myrmecochory refers to specialized seed dispersal by ants and is one of the world's major seed-dispersal syndromes, involving more than 11,000 angiosperm species (4.5 percent of the global total) from 334 genera and 77 families (Lengyel et al., 2009). Myrmecochorous plants have specially adapted seeds that possess a food appendage designed for ant attraction and transport (van der Pijl, 1982; Beattie, 1985). The appendages are typically arils, ariloides or caruncles (Gorb & Gorb, 2003), and are collectively referred to as elaiosomes because they are all rich in fatty acids. Generalized omnivorous ants are attracted to the elaiosomes and use them as handles for seed transportation (Beattie, 1985). Once seeds reach the nest, ants eat the elaiosome and typically discard the seed intact, in nest galleries or externally on nest middens or nearby refuse dumps, where they can potentially germinate and establish (Beattie, 1985; Hughes & Westoby, 1992; Manzaneda & Rey, 2012). Myrmecochory is particularly common among temperate forest herbs in the northern Hemisphere (Beattie & Culver, 1981; Gorb & Gorb, 2003) and sclerophyll shrubs of Mediterranean-climate landscapes in South Africa, southern Australia and southern Europe (Bond & Slingsby, 1983; Westoby et al., 1991; Garrido et al., 2002). In the past decade, the Brazilian Caatinga has been recognized as another hotspot of myrmecochory (Leal et al., 2007, 2015). Caatinga is a mosaic of xerophytic, deciduous, semiarid thorn scrubs and seasonally dry forests that covers 730,000 km2in northeastern Brazil (Instituto Brasileiro de Geografia e Estatística, 1985; Sampaio, 1995). The soils form a complex mosaic, ranging from nutrient-rich clays to nutrient-poor sands (Sampaio, 1995). Although the seeds of most Caatinga plants are dispersed abiotically (Griz & Machado, 2001; Tabarelli et al., 2003), a large number of species from many families rely on the seed dispersal services by ants (e.g. 25 percent of local woody flora in Leal et al., 2007). Myrmecochory is especially prevalent in the Euphorbiaceae, the second largest plant family in the Caatinga flora (Moro et al., 2014), where about 70 percent of its species – woody plants from the genera Cnidoscolus, Croton, Jatropha and Manihot – have their caruncle-bearing seeds dispersed exclusively by ants (Leal et al., 2015).

Original languageEnglish
Title of host publicationAnt-Plant Interactions
Subtitle of host publicationImpacts of Humans on Terrestrial Ecosystems
EditorsPaulo S. Oliveira, Suzanne Koptur
Place of PublicationUK
PublisherCambridge University Press
Chapter6
Pages112-132
Number of pages21
Edition1
ISBN (Electronic)9781316671825
ISBN (Print)9781107159754
DOIs
Publication statusPublished - 1 Jan 2017
Externally publishedYes

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