DOI: 10.5061/dryad.qn363dv
title: Data from: Invasion and high-elevation acclimation of the red imported fire ant, Solenopsis invicta, in the southern Blue Ridge escarpment region

description: The red imported fire ant (Solenopsis invicta) is a non-native invasive
 species that rapidly spread northward in the United States after its
 introduction from South America to the southern coast in the 1930s.
 Researchers predicted that the northward spread of this invasive ant would
 be limited by minimum temperatures with increased latitude and elevation
 in the Southern Appalachian Mountains. The presence of S. invicta at
 relatively high elevations north of their projected limits suggests
 greater cold tolerance than previously predicted; however, these
 populations might be ephemeral indications of strong dispersal abilities.
 In this study we investigated potential physiological and behavioral
 adaptations of S. invicta that would indicate acclimation to high
 elevation environments. We hypothesized that if S. invicta colonies can
 persist in colder climates than where they originated, we would find
 gradients in S. invicta worker cold tolerance along a montane elevational
 gradient. We also predicted that higher elevation S. invicta ants might
 require greater physiological costs to persist in the colder climate, so
 we measured colony lipid content to assess health status. Finally, we
 predicted that the ants might compensate for colder climates by adjusting
 microscale colony locations (e.g., nearer to radiant heat masses). For
 comparison, we also collected physiological temperature tolerance data for
 the co-occurring dominant native woodland ant Aphaenogaster picea. We
 found that S. invicta occurring at higher elevations exhibited greater
 physiological tolerance for cold temperatures as compared to
 lower-elevation conspecifics – a cold tolerance pattern that paralleled of
 the native A. picea ants along the same gradient. Whereas S. invicta had a
 higher tolerance for heat compared to A. picea, both exhibited a similar
 downward shift in thermal tolerances when moving up the elevational
 gradient. There was no change in S. invicta colony lipid content with
 elevation, suggesting that greater metabolic rates were not needed to
 sustain these ants through high-elevation winter dormancy. In addition, S.
 invicta ants at high elevations did not appear to offset the colder
 high-elevation temperatures by selecting nest sites proximate to thermal
 masses. 
description: ThermalToleranceData Thermal tolerance data (CTmin and CTmax) for two species of ant: Solenopsis invicta and Aphaenogaster picea. This file also includes collection dates and collection locations.   Lipid Analysis data Lipid Analysis for Solenopsis invicta ants. This file includes dry weights before and after lipid extraction and dates that the assays were run.   iButton temperature data for nine pairs of high-elevation Solenopsis invicta colonies iButton temperature data for nine pairs of high-elevation Solenopsis invicta colonies. Dates and times of temperature recordings are included. For each colony, temperature data from two iButtons is recorded (e.g. 1A1 and 1A2) and the average of those two is recorded in another column (e.g. 1A). Sheet two includes colony location and elevation. iButton.xlsx 34 high-elevation S. invicta colonies Location descriptions of 34 high-elevation Solenopsis invicta colonies. This file includes observational data about where colonies are located and what the nest is placed on or near.