Relationships between ambient temperature and diurnal variation in physiological responses to acute stress in the house sparrow, Passer domesticus
Description
These data include plasma glucose, corticosterone, heat shock proteins Hsc70 and Hsp90, and additional measures taken from wild house sparrows (Passer domesticus) at three sites in Australia. The goal of this data collection was to test how these plasma measures varied across latitude, time, and temperature. Climate change will alter the frequency and intensity of environmental extremes, as well as diurnal rates of environmental change. The daily reaction norms of wild animals show spatial and temporal plasticity to allow appropriate physiological responses to predictable environmental challenges, but these responses have rarely been quantified in wild birds. To address this, we determined whether physiological stress indices (corticosterone [CORT], glucose [GLU], and circulating heat shock proteins) vary across a latitudinal gradient, with ambient temperature (Ta) or time of day. We sampled wild house sparrows, Passer domesticus, across three locations with varying daily rates of Ta increases in 2015 and in 2019-2020 to determine whether physiological responses to capture and handling stress change diurnally. Consistent with predictions, plasma CORT and GLU increased in response to capture and handling stress. Baseline levels of CORT and GLU did not change during the day, but the amplitude of plasma CORT increase (delta CORT) in response to capture decreased as Ta increased, as was the case for GLU, in birds with initially high baseline CORT. Neither baseline nor stress-related plasma CORT or GLU differed consistently across sampling locations. Both heat-shock cognate 70 (Hsc70) and heat-shock protein 90α (Hsp90) showed clear temporal dynamics across the day. These results indicate temporal plasticity of reaction norms during the day (Hsp) and in response to daily Ta changes, as well as to acute stress (CORT and GLU), but they provide little evidence for such plasticity in reaction norms across our geographical range.
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Steps to reproduce
Field procedures: • Catch adult House Sparrows, Passer domesticus of known sex at (sub)urban sites located along a latitude gradient, using Japanese mist nets. All birds in the present study were caught during their breeding season in 2015-16. The study was repeated at the same sites and time of year, but on other birds, in 2019. Birds were caught from dawn to dusk and the time of capture, as well as ambient temperature at this time, were noted. • Collect a first blood sample (150 ul) from the jugular vein using a heparinized syringe within 3 minutes of a bird being netted. These samples are to be used to measure baseline concentrations of metabolites. • Place bird in an opaque bag for 30 min and then collect a second blood sample. These samples are to be used to measure handling/restraint (= stress-induced) concentrations of metabolites. • Collect standard morphometric data from each bird: Body mass, wing chord, tarsus length, furcular fat reserves, brood patch development (females). • Take a picture of the bib of each male by placing it in a standardized position (belly up) on a sheet of graduated paper. • Mark each bird with a uniquely numbered metal tarsal band, and release it where caught. Laboratory procedures: • Centrifuge blood samples and separately collect plasma and erythrocytes. • Store samples at -80C until assayed. • Assay plasma corticosterone, plasma glucose, and erythrocyte heat shock proteins Hsc70 and Hsp 90 using validated, standardized procedures. All samples are assayed in duplicate if sufficient volumes of plasma and erythrocytes are available. Correct heat shock protein measurements for protein concentrations (measured using the Bradford assay) of each sample. • Determine the bib size of each male from photos, using ImageJ software.