Ecological coupling of foraging and thermoregulation in harvester ants from a tropical deciduous forest in southern Mexico
- 1Universidad Autonoma del Estado de Morelos
Abstract
Diurnal ectotherms in hot and dry ecosystems face an acquisition trade-off between maximizing collective energy intake and minimizing individual exposure time. We employed optimal foraging and thermoregulation models to examine the surface foraging and thermoregulatory strategies of Pogonomyrmex barbatus foragers in response to habitat warming in a tropical deciduous forest. Foraging activity was evaluated using field-based thermal performance curves (fTPCs) for individual foraging speed and collective foraging success. Thermoregulation was assessed through indices of thermal unsuitability, as well as thermoregulatory effectiveness and exploitation. Our results show that afternoon conditions were significantly hotter and drier than those in the morning. Furthermore, the decoupling of fTPCs was dynamic; while the optimal temperature (Topt) for individual foraging speed remained stable at 44 degrees C, the Topt for collective foraging success shifted from 35 degrees C in the morning to 41 degrees C in the afternoon. This shift in foraging strategy, driven by stressful afternoon conditions, was reflected in a transition of the thermoregulatory strategy. Specifically, the probability of foraging activity decreased as thermal unsuitability increased, with a lower baseline in the afternoon. The thermoregulatory exploitation dropped from 94% in the morning to 63% in the afternoon. Based on thermoregulatory effectiveness, foragers transitioned from an active thermoregulatory strategy in the morning to a thermoconformist strategy in the afternoon while foraging on the surface. So, the observed colonies optimized the balance between individual foraging speed and collective foraging success through a thermoregulatory strategy that was primarily spatial in the morning and strictly temporal in the afternoon. A comparison with historical data from the same site reveals a 40% contraction in the total daily foraging window since 2013.
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BibTeX
@misc{valenciaesquivel2026ecological,
title = {{Ecological coupling of foraging and thermoregulation in harvester ants from a tropical deciduous forest in southern Mexico}},
author = {I. Valencia-Esquivel and I. Inchaurregui and A. Martinez and D. Zepeda and E. Arce and M. Osorio-Beristain},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.05.752865},
url = {https://www.biorxiv.org/content/10.64898/2026.10.05.752865v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Ecological coupling of foraging and thermoregulation in harvester ants from a tropical deciduous forest in southern Mexico
AU - I. Valencia-Esquivel
AU - I. Inchaurregui
AU - A. Martinez
AU - D. Zepeda
AU - E. Arce
AU - M. Osorio-Beristain
PY - 2026
DA - 2026/10/05
PB - bioRxiv
DO - 10.64898/2026.10.05.752865
UR - https://www.biorxiv.org/content/10.64898/2026.10.05.752865v1
AB - Diurnal ectotherms in hot and dry ecosystems face an acquisition trade-off between maximizing collective energy intake and minimizing individual exposure time. We employed optimal foraging and thermoregulation models to examine the surface foraging and thermoregulatory strategies of Pogonomyrmex barbatus foragers in response to habitat warming in a tropical deciduous forest. Foraging activity was evaluated using field-based thermal performance curves (fTPCs) for individual foraging speed and collective foraging success. Thermoregulation was assessed through indices of thermal unsuitability, as well as thermoregulatory effectiveness and exploitation. Our results show that afternoon conditions were significantly hotter and drier than those in the morning. Furthermore, the decoupling of fTPCs was dynamic; while the optimal temperature (Topt) for individual foraging speed remained stable at 44 degrees C, the Topt for collective foraging success shifted from 35 degrees C in the morning to 41 degrees C in the afternoon. This shift in foraging strategy, driven by stressful afternoon conditions, was reflected in a transition of the thermoregulatory strategy. Specifically, the probability of foraging activity decreased as thermal unsuitability increased, with a lower baseline in the afternoon. The thermoregulatory exploitation dropped from 94% in the morning to 63% in the afternoon. Based on thermoregulatory effectiveness, foragers transitioned from an active thermoregulatory strategy in the morning to a thermoconformist strategy in the afternoon while foraging on the surface. So, the observed colonies optimized the balance between individual foraging speed and collective foraging success through a thermoregulatory strategy that was primarily spatial in the morning and strictly temporal in the afternoon. A comparison with historical data from the same site reveals a 40% contraction in the total daily foraging window since 2013.
ER -