Spatial variation in the evolutionary potential and constraints of basal metabolic rate and body mass in a wild bird

Organismal energy budget is strongly related to resource consumption, performance, and fitness. Hence, understanding the evolution of key energetic traits, such as basal metabolic rate (BMR), in natural populations is central for understanding life-history evolution and ecological processes. Here we used quantitative genetic analyses to study evolutionary potential of BMR in two insular populations of the house sparrow (Passer domesticus). We obtained measurements of BMR and body mass (Mb) from 911 house sparrows on the islands of Leka and Vega along the coast of Norway. These two populations were the source populations for translocations to create an additional third, admixed "common garden" population in 2012. With the use of a novel genetic group animal model concomitant with a genetically determined pedigree, we differentiate genetic and environmental sources of variation, thereby providing insight into the effects of spatial population structure on evolutionary potential. We found that the evolutionary potential of BMR was similar in the two source populations, whereas the Vega population had a somewhat higher evolutionary potential of Mb than the Leka population. BMR was genetically correlated with Mb in both populations, and the conditional evolutionary potential of BMR (independent of body mass) was 41% (Leka) and 53% (Vega) lower than unconditional estimates. Overall, our results show that there is potential for BMR to evolve independently of Mb, but that selection on BMR and/or Mb may have different evolutionary consequences in different populations of the same species.All analyses were performed in R (version 4.1.0), using the packages MCMCglmm, nadiv, pedantics, tidyverse and boot. Funding provided by: Norges ForskningsrådCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100005416Award Number: 274930Funding provided by: Norges ForskningsrådCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100005416Award Number: 302619Funding provided by: Norges ForskningsrådCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100005416Award Number: 223257Funding provided by: Norges Teknisk-Naturvitenskapelige UniversitetCrossref Funder Registry ID: http://dx.doi.org/10.13039/100009123Award Number:Phenotypic data were collected during winters (February-Marc) in 2012–2015. Wild house sparrows were captured, and their metabolic rates were measured as oxygen consumption rates (mL O2 h-1) during evening-night, and the lowest 20-minute running average oxygen consumption rate was recorded as the basal metabolic rate (BMR). Simultaneously, body mass was measured to the nearest 0.1 g. A blood sample (approx 25 μL) was obtained by brachial venipuncture and stored in absolute ethanol. The blood samples were used for genetic analyses, by genotyping 603 SNP markers that were used for pedigree reconstruction using the R package sequoia. The data and code sections provided in this archive provide further analyses of these data