Global Change Impacts On Ant-Mediated Seed Dispersal In Eastern North American Forests

Abstract

Introduction Global change alters the distributions and interactions of species through large-scale fragmentation and alteration of forests, as well as rapid increases in both the mean and variability of temperatures, both augmenting the introduction of exotic species. The impacts of these changes are not ubiquitous, but rather context-dependent and may be considered drivers or secondary forces for which shifts in communities, and therefore species interactions, may occur. Ant-mediated seed dispersal (myrmecochory) is a climate-dependent interaction. Both ants and plants rely on temperature to cue seasonal activity, such as the timing of life history events, and changes in temperature prompt changes in ant community composition, behavior, and interactions with other ants. Climatic changes disrupt the synchrony between ant-dispersed (myrmecochorous) plant seed release and the initiation of ant foraging in the spring. Moreover, changes in habitat structure change the template by which plants and ants interact, in that habitat fragmentation changes ant dispersal behavior away from forest edges so that these become formidable barriers for myrmecochorous plants. In addition, habitat fragmentation increases exotic ant invasion, as does warming, and both can disrupt ant-plant seed dispersal interactions. Here, we examine the impacts of three major agents of global change – forest fragmentation, invasive species, and climate change – on the interactions between woodland myrmecochores and ants in eastern North America (NA). The ant-plant interaction may be unbalanced and nonspecific, in that many plants rely on a few ant species, therefore, seed dispersal depends strongly on the presence of particular ant species (and primarily of one genus in eastern NA). Thus, we focus on the main seed-dispersing genus of ants in eastern NA deciduous forests, Aphaenogaster, to investigate potential global change impacts on the interaction. Alone, and in concert, global change drivers pose great challenges for ant-mediated seed dispersal in eastern NA. Ant-Mediated Seed Dispersal Myrmecochory is a climate-mediated interaction that occurs worldwide and is employed by at least 11,000 plant species (Gorb & Gorb, 2003; Lengyel et al., 2009; Rico-Gray & Oliveira, 2007). Plants in the myrmecochore guild (sensu stricto) produce lipid-rich external appendages on the seed surface (elaiosomes) that induce solitary foraging, nongranivorous ants to retrieve seeds back to their colony (Marshall et al., 1979). Ant workers then remove elaiosomes and feed them to larvae, and the seeds are discarded undamaged – either within nest midden or near the ant nest (Canner et al., 2012; Handel, 1976; Servigne & Detrain, 2008).

Publication Date

1-1-2017

Publication Title

Ant-Plant Interactions: Impacts of Humans on Terrestrial Ecosystems

Number of Pages

93-111

Document Type

Article; Book Chapter

Personal Identifier

scopus

DOI Link

https://doi.org/10.1017/9781316671825.006

Socpus ID

85048151277 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85048151277

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