Data for: Evolution of avian heat tolerance: The role of atmospheric humidity

The role of atmospheric humidity in the evolution of endotherms’ thermoregulatory performance remains largely unexplored, despite elevated atmospheric humidity being known to impede evaporative cooling capacity. Using a phylogenetically informed comparative framework, we tested the hypothesis that pronounced hyperthermia tolerance among birds occupying humid lowlands evolved to reduce the impact of humidity-impeded scope for evaporative heat dissipation by comparing heat tolerance limits (HTL; maximum tolerable air temperature), maximum body temperatures (Tbmax) and associated thermoregulatory variables in humid (19.2 g H2O m− 3) versus dry (1.1 g H2O m− 3) air among 30 species from three climatically distinct sites (arid, mesic montane and humid lowland). Humidity-associated decreases in evaporative water loss and resting metabolic rate were 27 - 38% and 21 - 27%, respectively, and did not differ significantly between climatic sites. Decreases in heat tolerance limits were significantl..., Materials and Methods
Study areas
We collected data at three climatically distinct areas (hot arid, mesic montane and humid lowland) between latitudes of 27.90° and 30.04° S in South Africa [see Table 1 for general information and climatic data (Smit et al. 2011, Fick and Hijmans 2017)].
Study species
We collected physiological data under either dry (~1 g H2O m-3) or humid conditions (~19 g H2O m-3). Overall, our analysis includes data from 627 individuals (humid, n = 307; dry, n = 320) representing 30 species, 15 families and three orders – Passeriformes, Piciformes and Coraciiformes. Humidity and dry protocol data were collected during the austral summer between January – February (2021) [arid-zone species (see Appendix S1: Table S3, S4 and S5a and S5b)] and September 2021 – February (2022) [montane species (see Appendix S1: Table S9 and S10) and lowland species (see Appendix S1: Table S6, S7 and S8)]. Where available, data for species responses under dry air conditions at our montane..., , This README file was generated on 2024-01-27 by Marc Freeman

GENERAL INFORMATION

1. Title of Dataset: Data for: Evolution of avian heat tolerance: The role of atmospheric humidity

2. Author Information
Corresponding Investigator
Name: Dr Marc Trevor Freeman
Institution: South African National Biodiversity Institute and University of Pretoria, Pretoria, South Africa
Email:

Co-investigator 1
Name: Ms Bianca Coulson
Institution: South African National Biodiversity Institute and University of Pretoria, Pretoria, South Africa

Co-investigator 2
Name: Mr James Curtis Short
Institution: South African National Biodiversity Institute and University of Pretoria, Pretoria, South Africa

Co-investigator 3
Name: Dr Celiwe Angel Ngcamphalala
Institution: Department of Biological Sciences, University of Cape Town, Cape Town, South Africa

Co-investigator 4
Name: Mr Mathome Otto Makola
Institution: South African National Biodiversit...