Habitat disturbance modifies dominance, coexistence, and competitive interactions in tropical ant communities

Abstract

1. Interspecific competition is a major structuring principle in ecological communities. Despite their prevalence, the outcome of competitive interactions is hard to predict, highly context-dependent, and multiple factors can modulate such interactions. 2. We tested predictions concerning how competitive interactions are modified by anthropogenic habitat disturbance in ground-foraging ant assemblages inhabiting fragmented Inter-Andean tropical dry forests in southwestern Colombia, and investigated ant assemblages recruiting to baits in 10 forest fragments exposed to varying level of human disturbance. 3. Specifically, we evaluated how different components of competitive interactions (patterns of species co-occurrence, resource partitioning, numerical dominance, and interspecific trade-offs between discovery and dominance competition) varied with level of habitat disturbance in a human-dominated ecosystem. 4. Multiple lines of evidence suggest that the role of competitive interactions in structuring ground-foraging ant communities at baits varied with respect to habitat disturbance. As disturbance increased, community structure was more likely to exhibit random co-occurrence patterns, higher levels of monopolization of food resources by dominant ants, and disproportionate dominance of a single species, the little fire ant (Wasmannia auropunctata). At a regional scale, we found evidence for a trade-off between dominance and discovery abilities of the 15 most common species at baits. 5. Together, these results suggest that human disturbance modifies the outcome of competitive interactions in ground-foraging ant assemblages and may promote dominant species that reduce diversity and coexistence in tropical ecosystems.

Plant diversity and functional identity alter ant occurrence and activity in experimental grasslands

“…In addition to pitfall trapping and colony counting, we carried out baiting experiments because these are useful to study patterns of ant activity (Achury et al, 2020; Prather et al, 2018). While differences in attraction between sugar and tuna were expected, there was a striking difference in sugar versus tuna recruitment, both in the number of ants observed and in the time at which the first ant appeared after bait placement.…”

“…Baiting experiments are used to approximate ephemeral protein, lipid, and carbohydrate resources such as carrion, large dead insects, or nectar. While baits may bias estimates of community composition, particularly by excluding dietary specialists (Bestelmeyer et al, 2000), they are widely used in studies of ant community ecology yielding information about ant resource use (Achury et al, 2020). Although the nutrient composition of the bait does not significantly affect the ant composition visiting these resources (Bestelmeyer et al, 2000), volatiles are important for ant attraction, resulting, for example, in lower levels of attraction for pure sugar baits that emit little or no volatiles compared with the highly odorous tuna baits.…”

The role of anthropogenic disturbance and invasion of yellow crazy ant in a recent decline of land crab population

“…Although many studies focused on the effect of habitat disturbance on overall ant assemblages 54 – 56 , our current study is one of the few attempts to correlate worker abundance of single invasive ant species and the intensity of human disturbance. Our data show a clear trend of higher worker abundance at human-modified areas with major anthropogenic modifications such as agricultural land, farmhouses, forest edges, or fishing ports.…”

Patrones de actividad de hormigas urbanas y su preferencia de cebos en Alajuela, Costa Rica

“…La actividad de las distintas especies de hormigas coincide con lo esperado por condiciones ambientales (Silva, 2010) y competencia entre especies (Hölldobler y Wilson 1990, Achury et al, 2008. La preferencia por ciertos alimentos, como soluciones azucaradas, no es sorprendente porque está bien documentada (Rico & Moráis, 2006).…”

“…Algunas especies dominan mediante la agresión (Hölldobler & Wilson, 1990), como se observó en Tapinoma melanocephalum, Linepithema angulatum y Camponotus atriceps. En este estudio, Camponotus atriceps, bastante agresiva, desplazó a Pheidole pugnax y a Camponotus novogranadensis (ambas especies escaseaban en los cebos en la noche, cuando eran dominados por C. atriceps; ver Hölldobler & Wilson, 1990;Achury, Chacon de Ulloa & Arcilla, 2008).…”