Thermal regulation of ant colonies is driven by biological rhythms and acclimation

McGlynn, Terry 1 ; Clifton, Elizabeth 2 ; Escamilla, Sasha1; Garcia, Jade1; Santizo, Ashley1; Tafoya, Diana1

Published Sep 30, 2026 on Dryad. https://doi.org/10.5061/dryad.hdr7sqvz6

Data files

Sep 30, 2026 version files 162.71 KB

Abstract

Two experiments were conducted on the ant Ectatomma ruidum in Costa Rica. In one experiment, foraging ants were marked in the field, and a knockdown thermal tolerance assay was conducted in the laboratory. In the second, colonies were excavated and brought into the laboratory at different experimental treatments and subjected to the same knockdown assay. Columns in the data file indicate treatment, day, time, assay protocol, and tolerance threshold.

Dataset DOI: 10.5061/dryad.hdr7sqvz6

Description of the data and file structure

Ants were collected from the field, subjected to experimental treatments or marked for timing of field foraging and a knockdown assay was conducted to measure thermal tolerance on individuals.

EctaThermalAnalyses.R

This is the code for statistical analyses and figures.

MainExptsForRCleanedUp.csv

796 rows, one per ant; 25 columns. Cells that do not apply to a given ant are coded n/a. All data were collected at La Selva Biological Station, Costa Rica, in May–June 2018.

Variables:

1. AntID — Unique identifier for each ant. Integer, 175–987. No units.

2. ColonyID — Colony of origin, coded as year-colony number (e.g. 18-34 = colony 34 of 2018). 21 colonies. Categorical.

3. ThermalPersistence — Thermal tolerance, the response variable: time until the ant failed to right itself when held at 42 °C. Units: whole minutes, recorded at 1-minute intervals. Range 3–35.

4. ForagerOrColony — How the ant was obtained. Colony = taken from an excavated colony or a laboratory colony fragment; FreshForager = collected while foraging in the field.

5. CollectionDate — Date the ant was collected from the field. Format day-month (e.g. 27-May); all dates 2018.

6. CollectionTime — Local clock time of collection. Format h:mm:ss AM/PM.

7. #ofForagersRemovedPreviously — Count of foragers previously removed from the same colony in the preceding sampling event. Integer, 0–20. Recorded for 68 ants; n/a otherwise.

8. TempAtCollection — Air temperature at the time of collection. Units: degrees Celsius. Range 24–34. Recorded for 157 ants; n/a otherwise.

9. Manipulation — Thermal treatment experiment only: the thermal environment of the ant's colony fragment. Ambient = laboratory room tracking outdoor shade temperature; Ambient+3°C = ambient plus 3 °C; Constant 24°C = held at a constant 24 °C; Field Control = ant from the undisturbed paired colony in the field. n/a for marking experiment ants.

10. Marking — Color of enamel paint on the gaster, which records the period when the ant was seen foraging; Green, Gold, White,Green/Gold, White/Green; None = unmarked.

11. ExperimentName — Experiment the ant belongs to. TheMarking = marking experiment (Experiment 1, 399 ants); CircadianRhythm = thermal treatment experiment (Experiment 2, 397 ants).

12. MarkingTimeCategory — Marking experiment only: when the ant was observed foraging. Afternoon = marked at daily thermal maxima; Morning = marked at daily thermal minima; Both = marked in both periods; Unmarked = never observed foraging (non-forager). n/a for thermal treatment ants.

13. LocationInNest — Marking experiment only: position in the nest at excavation. Upper = upper two chambers; Deep = lower chambers. n/a for thermal treatment ants.

14. StorageLocation — Where the ant was held between collection and assay. Amb lab = ambient laboratory; Lab 10 (also written lab10) = laboratory room 10; Office = air-conditioned office. Lab 10 is the office.

15. RampingDate — Date of the thermal tolerance assay. Format day-month; all dates 2018.

16. RampingTimeStart — Local clock time the assay began. Format h:mm:ss AM/PM. Range 05:00–16:55.

17. RampingTimeCategory — Time of day of the assay, coded separately for each experiment. Thermal treatment experiment: thermal minimum = assays at the daily thermal minimum (05:00–07:30); thermal maximum = assays at the daily thermal maximum (13:00–14:00). Marking experiment: morning = 09:00–11:30; afternoon = 12:40–17:00.

18. MinutesElapsedBetweenCollectionandRamping — Elapsed time between field collection and the start of the assay. Units: minutes. Range 11–5,627.

19. paintedornot — Whether the ant carried a paint mark. painted, notpainted.

20. StorageContainer — Container the ant was held in before the assay. Ziploc bag; green tub with closed lid (also spelled green tub with close lid and green tub with a closed lid); ziploc bag.

21. WeatherAtCollection — Sky conditions when the ant was collected. Sunny, Cloudy, Overcast.

22. Site — Location of the colony within the study area: CES-0, CES-50, Porch. These are three locations at La Selva Biological Station; CES-0= Camino Experimental Sur indicates the start of the trail; CES-50 indicates near the 50 meter signpost on the same trail; Porch indicates areas within a few meters of the a porch of the lab buildings, colloquially known as "the porch" at the field station.

23. Status — Event indicator required by the Cox proportional hazards model. 1 = the ant reached the knockdown endpoint. All 796 ants are 1; no observations were censored.

24. DaysInTreatment — Days the colony fragment had been held in its thermal treatment when the ant was assayed. Units: days, 1–4. Coded 0 for field controls and for marking experiment ants, neither of which received a treatment.

25. CorrectRampingDate — Assay date in m/d/yy format (e.g. 5/28/18). Identical to RampingDate in all 796 rows.

Code/software

Statistical analyses were run in R, and associated packages are listed within the files.