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Data from: Why do ants differ in acclimatory ability? Biophysical mechanisms behind cuticular hydrocarbon acclimation across species

Citation

Baumgart, Lucas et al. (2022), Data from: Why do ants differ in acclimatory ability? Biophysical mechanisms behind cuticular hydrocarbon acclimation across species, Dryad, Dataset, https://doi.org/10.5061/dryad.k98sf7m8n

Abstract

Maintaining water balance is vital for terrestrial organisms. Insects protect themselves against desiccation via cuticular hydrocarbons (CHCs). CHC layers are complex mixtures of solid and liquid hydrocarbons, with a surprisingly diverse composition across species. This variation may translate to differential phase behaviour, and hence varying waterproofing capacity. This is especially relevant when temperatures change, which requires acclimatory CHC changes to maintain waterproofing. Nevertheless, the physical consequences of CHC variation are still little understood. We studied acclimatory responses and their consequences for CHC composition, phase behaviour, and drought survival in three congeneric ant species. Colony fragments were kept under cool, warm, and fluctuating temperature regimes. Lasius niger and platythorax, both of which are rich in methyl-branched alkanes, showed largely predictable acclimatory changes of the CHC profile. In both species, warm acclimation increased drought resistance. Warm acclimation increased the proportion of solid compounds in L. niger but not in L. platythorax. In both species, the CHC layer formed a liquid matrix of constantly low viscosity, which contained highly viscous and solid parts. This phase heterogeneity may be adaptive, increasing robustness to temperature fluctuations. In L. brunneus, which is rich in unsaturated hydrocarbons, acclimatory CHC changes were less predictable, and warm acclimation did not enhance drought survival. The CHC layer was more homogenous, but matrix viscosity changed with acclimation. We showed that ant species use different physical mechanisms to enhance waterproofing during acclimation. Hence, the ability to acclimate, and thus climatic niche breadth, may strongly depend on species-specific CHC profile.

Methods

We studied ants of the three species Lasius niger, Lasius platythorax and Lasius brunneus. Per species, 12 colonies were collected and divided into sub-groups. These were maintained at different climate regimes: constant 20°C, constant 28°C or fluctuating temperature (20°C at night and 28°C during the day, with 4h-ramps in between). After three weeks, we analysed cuticular hydrocarbons of the ants using GC-MS. Viscosity of some of these CHC extracts was analysed using microrheology. Melting ranges of the CHCs were determined using differential scanning calorimetry (DSC), based on pooled CHC samples. Finally, we determined drought survival of the differently acclimated ants at 20°C and at 28°C.

Usage Notes

Microsoft Excel

Funding

Deutsche Forschungsgemeinschaft, Award: ME 3842/4-2

Deutscher Akademischer Austauschdienst, Award: 57388961

Bundesministerium für Bildung und Forschung

PHC Procope 2018, Award: 40427NM

Ministère de l’Europe et des Affaires étrangères

Ministère de l’Enseignement Supérieur, de la Recherche et de l’Innovation

Deutsche Forschungsgemeinschaft, Award: ME 3842/6-1

Deutscher Akademischer Austauschdienst France, Award: 40427NM