Hatching plasticity is associated with a more advanced stage at hatching in an Ambystoma with terrestrial eggs

These data are from a 2019 study of embryonic development in marbled salamander (Ambystoma opacum) and ringed salamander (Ambystoma annulatum). Egg masses were collected in Arkansas in the fall of 2019 and transported to the University of North Carolina Asheville. Clutches were split and embryos were reared in one of two environments mimicking the terrestrial environment typical of A. opacum nests and the aquatic environment typical of A. annulatum egg masses. Response variables recorded include number of embryos that hatched, age (days) at hatching, Harrison stage at hatching, and dry mass at hatching., All embryos were collected as either an egg mass, constituting a group of presumed half or full siblings surrounded by a jelly layer (ringed salamander), or a clutch of half or full siblings found together in a nest site (marbled salamander). Hereafter, we refer to both of these grouping as clutches. Clutches were kept separate in gas-permeable bags for transport back to Asheville, NC.
We removed jelly from ringed salamander embryos by gently pulling the jelly apart and releasing intact, encapsulated embryos into tap water (aged to allow chlorine to evaporate before use). Marbled salamander embryos are not encased in jelly so were not separated, but were rinsed in the same tap water to remove sediment. 
Each clutch was divided into two treatment groups of 20 embryos. One group was placed in 50 ml specimen jar submerged in ~ 40 ml aged tap water (water treatment) whereas the other group was placed in an identical jar with ~ 1 ml aged tap water to prevent desiccation (air treatment). Thes..., , # Data from: Hatching plasticity is associated with a more advanced stage at hatching in an Ambystoma with terrestrial eggs

[https://doi.org/10.5061/dryad.f4qrfj72](https://doi.org/10.5061/dryad.f4qrfj72)

## Description of the data and file structure

The data are organized in an .xlsx file with each embryo on its own line. The data are organized with the following headings:

species: *Ambystoma annulatum* or *Ambystoma opacum*
clutch: Unique egg mass identification number. Each mass collected from the field is assumed to have been laid by a single female, such that embryos from the same mass (clutch) are half or full siblings.
trt: Treatment, indicates whether the embryo was reared in an Air or Water treatment.
jar: Each rearing jar was giving a unique number. Embryos in the same jar were siblings. Two jars, one for each treatment, were established from each clutch.
ind: Number given to individual embryos.
startdate: Date the embryo first entered the experimental treatment.
hatch: Bi...