DOI: 10.5061/dryad.f4qrfj72k
title: Data from: Hatching plasticity is associated with a more advanced stage at hatching in an Ambystoma with terrestrial eggs

description: 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.
description: 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). These two treatments were identical
 to the “saturated” and “air” treatments in Hale et al. (2016
 <em>Evolutionary Ecology</em>). In the water treatment, air
 was pumped into the jar via an airstone inserted through the jar lid,
 submerged in the water, and connected through tubing to an aquarium pump.
 Identical lids with airstones were placed on jars in the air treatment.
 However, due to difficulty maintaining air pressure from our pumps when
 connected to a high number of jars, airstones on air treatment jars were
 not connected to an air pump and lids were left loose on the jars to allow
 air circulation. All jars were randomly situated in a Conviron CMP6050
 growth chamber (Controlled Environments Limited, Manitoba) at 20 °C, 80 %
 relatively humidity, with a 12 h:12 h light:dark cycle. In the air
 treatment, embryos were moistened, as needed, to prevent desiccation;
 embryos rested in a small puddle of water in the bottom of the jar, but
 were not submerged. We inspected all embryos under a
 dissecting microscope daily and recorded the number of live, dead, and
 hatched embryos. Embryos were scored as dead if the egg membranes were
 opaque or if the yolk and embryo were collapsed and non-spherical. The
 latter often occurred in early stage embryos. The minimum and maximum
 embryonic stage (Harrison, 1969) of live, developing embryos were recorded
 for each jar and were later converted to median stage to assign the jar a
 single stage value. The embryonic stage upon hatching was recorded for
 each individual and the first five hatchlings per jar were euthanized in
 MS-222 and preserved in Shandon<sup>TM</sup>
 Glyo-Fixx<sup>TM</sup> (Richard Allan Scientific, Kalamazoo,
 MI, USA) before being vacuum dried for 48 h and weighed to the nearest 10
 g on a Mettler-Toledo XP2U microbalance (Mettler-Toledo LLC,
 Columbus, OH, USA).
description: # 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: Binary; indicates whether or not the embryo hatched. enddate: Date on which the embryo died or hatched. In both cases, embryos were removed from the jar on this date. stage: Harrison (1969) stage at hatching. mass: Dry mass (mg) at hatching. Only 5 embryos from each jar were vacuum dried and weighed. Therefore, many cells in this column are left blank and will be scored as "*NA"* automatically upon import into R. age: Number of days between entering a treatment and being scored as dead or hatched. Calculated as enddate - startdate. ## Sharing/Access information These data are original and are not compiled from other sources. If researchers have difficulty accessing these data, they can contact the authors for files or explanation. The data correspond to a manuscript submitted to *Ecology and Evolution.* ## Code/Software An R script is provided with the data file. The data will load in the first lines of the script, if the data file is located in the same directory at the script file.