Abiotic mediation of a mutualism drives herbivore abundance.

Species abundance is typically determined by the abiotic environment, but the extent to which such effects occur through the mediation of biotic interactions, including mutualisms, is unknown. We explored how light environment (open meadow vs. shaded understory) mediates the abundance and ant tending of the aphid Aphis helianthi feeding on the herb Ligusticum porteri.

Nutritional asymmetries are related to division of labor in a queenless ant.

Eusocial species exhibit pronounced division of labor, most notably between reproductive and non-reproductive castes, but also within non-reproductive castes via morphological specialization and temporal polyethism. For species with distinct worker and queen castes, age-related differences in behavior among workers (e.g.

Trophic ecology of the invasive argentine ant: spatio-temporal variation in resource assimilation and isotopic enrichment.

Studies of food webs often employ stable isotopic approaches to infer trophic position and interaction strength without consideration of spatio-temporal variation in resource assimilation by constituent species. Using results from laboratory diet manipulations and monthly sampling of field populations, we illustrate how nitrogen isotopes may be used to quantify spatio-temporal variation in resource assimilation in ants. First, we determined nitrogen enrichment using a controlled laboratory experiment with the invasive Argentine ant (Linepithema humile).

Stable isotope and elemental analysis in ants.

Over the past 20 yr, the use of stable isotopes to infer feeding ecology and the examination of how energetic and elemental exchanges are affected by and affect life (ecological stoichiometry) have gained momentum. The ecological diversity of ants makes them interesting models to explore dietary ecology and their role in food webs. Moreover, their ecological dominance in most habitats facilitates sampling.

Trophic ecology of invasive Argentine ants in their native and introduced ranges.

Although the ecological effects of invasions often become obvious soon after introduced species become established, more gradual effects may take years to manifest and can thus require long-term data for quantification. We analyzed an 8-year record of stable isotope data on Argentine ants (Linepithema humile) from southern California to infer how the trophic position of this widespread invasive species changes over time as native ant species are displaced. We couple this longitudinal analysis with a biregional comparison of stable isotope data (delta(15)N) on ants from Argentina (native range) and California (introduced range) to quantify (i) how the trophic position of L.

Friend or foe? A behavioral and stable isotopic investigation of an ant-plant symbiosis.

In ant-plant symbioses, the behavior of ant inhabitants affects the nature of the interaction, ranging from mutualism to parasitism. Mutualistic species confer a benefit to the plant, while parasites reap the benefits of the interaction without reciprocating, potentially resulting in a negative impact on the host plant. Using the ant-plant symbiosis between Cordia alliodora and its ant inhabitants as a model system, I examine the costs and benefits of habitation by the four most common ant inhabitants at La Selva Biological Station, Costa Rica.