Variation in the thermal plasticity of avian embryos is produced by the developmental environment, not genes

Limited evidence suggests that variation in phenotypic plasticity within populations may arise largely from environmental sources, thereby constraining its evolvability. This is of concern for temperature-sensitive metabolism in the face of climate change. We quantified the relative influence of the developmental environment versus genes on the metabolic plasticity of avian embryos to temperature. We partially cross-fostered 602 house sparrow eggs (Passer domesticus), measured the heart rate plasticity of these embryos to egg temperature, and partitioned variance in plasticity. We found that the foster (incubation) environment was the sole meaningful source of variance in embryonic plasticity (not genes, pre-laying effects, or ambient conditions). In contrast to heart rate plasticity, nestling growth was influenced by the foster environment, genes/pre-laying parental effects, and ambient conditions. Although embryonic plasticity to temperature varied in this population, these results su..., In this study, we cross-fostered the eggs of house sparrows in a free-living nest box population located at the University of Kentucky. Nests were paired into dyads, and two eggs were reciprocally swapped between the two nests within the dyad upon the completion of egg laying. We then repeatedly measured the heart rate, egg temperature, and egg mass for all individual eggs. Upon hatching, we repeatedly measured the tarsus length of nestlings until they fledged the nest. Data is presented as it was entered., , # **Variation in the thermal plasticity of avian embryos is produced by the developmental environment, not genes**

**Description of the data collection**

In this study, we cross-fostered the eggs of house sparrows in a free-living nest-box population located at the University of Kentucky. Nests were paired into dyads, and two eggs were reciprocally swapped between the two nests within the dyad upon the completion of egg laying. We then repeatedly measured the heart rate, egg temperature, and egg mass for all individual eggs. Upon hatching, we repeatedly measured the tarsus of nestlings until they fledged the nest. Data is presented as it was entered.

**Description of the data and file structure**

Data is included as an excel file. Here is a description of the contents of each column:

* eggID: individual egg identity
* originID: nest of origin identity
* fosterID: foster nest identity
* dyadID: experimental dyad identity
* order: lay order for each egg
* stage: whether the individua...