DOI: 10.5061/dryad.8sf7m0cvk
title: Heat-induced maternal effects shape avian eggshell traits and embryo development and phenotype at high incubation temperatures

description: Phenotypic plasticity is an important avenue by which organisms may
 persist in the face of rapid environmental change. Environmental cues
 experienced by the mother can also influence the phenotype of offspring, a
 form of plasticity called maternal effects. Maternal effects can
 adaptively prepare offspring for the environmental conditions they will
 experience, however, their ability to buffer offspring against
 environmental stressors as embryos is understudied. Using captive zebra
 finches, we performed a maternal-offspring environmental match-mismatch
 experiment utilizing a 2x2x2 factorial design. Mothers were exposed to a
 mild heat conditioning (38 °C) or control (22 °C) treatment as juveniles,
 an acute high heat (42 °C) or control (22 °C) treatment as adults, then
 paired for breeding. The eggs produced by those females were incubated at
 a hyperthermic (38.5 °C) or optimal temperature (37.2 °C). We found that
 when mothers were exposed to a mild heat conditioning as juveniles, their
 embryos exhibited reduced water loss, longer development times, and
 produced hatchlings with heavier pectoralis muscles when incubated at high
 incubation temperatures, compared to embryos from control mothers. Mothers
 exposed to both the mild heat conditioning as juveniles and a high heat
 stressor as adults produced eggs with a higher density of shell pores, and
 embryos with lower heart rates during development. However, there was a
 cost when there was a mismatch between maternal and embryo environment.
 Embryos from these conditioned and heat-stressed mothers had reduced
 survival at control incubation temperatures, indicating the importance of
 offspring environment when interpreting potential adaptive effects.
description: # Heat-induced maternal effects shape avian eggshell traits and embryo
 development and phenotype at high incubation temperatures
 [https://doi.org/10.5061/dryad.8sf7m0cvk](https://doi.org/10.5061/dryad.8sf7m0cvk) Give a brief summary of dataset contents, contextualized in experimental procedures and results. ## Description of the data and file structure The uploaded data files both contain the experimental group designation for each zebra finch mother as well as her offspring. The "Embryo" data file also contains measurements recorded from offspring both *in ovo* and after hatch, e.g. egg mass, time of mortality, survival, heart rates, mass change, hatch mass, and organ masses. The "Eggshell" data file also contains eggshell measurements such as the average eggshell thickness, the lowest thickness, the number of eggshell fragments used from each egg, the total area of the eggshell fragments, the number of eggshell pores, and the pore density. Below is a description of the values found in the file and the abbreviations used. NA values were used if a timely measurement could not be obtained or if embryos died due to damage to the eggshells (e.g. cracks due to collisions in the incubator). **Embryo data file** * FID - a unique identification number that corresponds to each zebra finch mother. * jtreat - the treatment group that the mothers were exposed to as juveniles. * atreat - the treatment group that the mothers were exposed to as adults. * treatment - a variable that represents the 4 potential combinations of juvenile and adult treatments. * juv:inc - a variable that represents the 4 potential combinations of maternal juvenile and offspring incubation treatments. * fulltreatment - a variable that represents the 8 potential combinations of maternal juvenile, maternal adult, and offspring incubation treatments. * Date laid - the date on which each individual egg was laid. * timelaid - a standardized estimate for the time at which eggs were laid (24 hour time). * nestid - the genetic nest from which each egg originated. * layorder - the order in which the egg was laid in the clutch. * eggid - a unique identification number used for each egg, which is the combination of the "nestid" and "layorder". * sex - the sex of the individual embryo. * eggmass - the mass of the egg on the day it was laid, measured prior to incubation (g). * inctreat - the incubation treatment group that offspring were exposed to. * fertility - whether an individual egg was fertile or infertile. * morttime - the estimated embryonic developmental stage (very early = 1, early = 2, mid = 3, late = 4, very late = 5, pipping = 6) at which mortality occurred or if they successfully hatched (7). * survival - whether the embryo died during development (1) or survived and successfully hatched (0). * survival2 - a text only version of the above "survival" variable. Whether the embryo died during development or survived and successfully hatched. * d4hr - the heart rate of embryos at day 4 of embryonic development (bpm). * d4time - the time (in seconds) and which the heart rate measurement was taken, starting when the egg was initially removed from the incubator. * d4incorder - the order in which the egg was removed from the incubator when heart rate measurements had to be recorded for multiple embryos. * d10hr - the heart rate of embryos late in embryonic development, measured on day 10 for embryos in the high temperature incubator and day 11 for embryos in the control temperature incubator (bpm). * d10time - the time (in seconds) and which the heart rate measurement was taken, starting when the egg was initially removed from the incubator. * d10incorder - the order in which the egg was removed from the incubator when heart rate measurements had to be recorded for multiple embryos. * d10mass - the egg mass late in development, recorded after heart rate measurements (g). * wtchange - the difference in mass (g) between the initial egg mass and the egg mass recorded later in development (day 10 or 11). * Hdate - egg hatch date. * Htime - egg hatch time (24 hour time). * inctime - the amount of time (in days) between the egg was laid and when it hatched. * Edate - hatchling euthanasia/dissection date. * Etime - hatchling euthanasia/dissection time (24 hour time). * Timebtw - the time (in minutes) between hatch and euthanasia/dissection. * body - hatchling total body mass (g). * pec - hatchling pectoralis mass (g). * yolk - hatchling residual yolk mass (g). * heart - hatchling heart mass (g). **Eggshell data file** * nestid - the genetic nest/female the egg came from (provides the same information as "FID"). * layorder - the order in which the egg was laid in the clutch. * eggid - a unique identification number used for each egg, which is the combination of the "nestid" and "layorder". * avgthickness - the average thickness of an individual eggs shell (mm). * low - the lowest thickness of an individual eggs shell (mm). * Numfragments - the number of eggshell fragments used from each egg for measurement. * Totalarea - the total area of the eggshell fragments used from each individual egg (cm<sup>2</sup>). * Totalpores - the number of eggshell pores. * Poredensity - the pore density of individual eggs (pores/cm<sup>2</sup>). * jtreat - the treatment group that the mothers were exposed to as juveniles. * atreat - the treatment group that the mothers were exposed to as adults. * treatment - a variable that represents the 4 potential combinations of juvenile and adult treatments. * inctreat - the incubation treatment group that offspring were exposed to. * fulltreatment - a variable that represents the 8 potential combinations of maternal juvenile, maternal adult, and offspring incubation treatments. * juv:inc - a variable that represents the 4 potential combinations of maternal juvenile and offspring incubation treatments. * Date laid - the date on which each individual egg was laid. * timelaid - a standardized estimate for the time at which eggs were laid (24 hour time). * eggmass - the mass of the egg on the day it was laid, measured prior to incubation (g). * fertility - whether an individual egg was fertile or infertile. * morttime - the estimated embryonic developmental stage (very early = 1, early = 2, mid = 3, late = 4, very late = 5, pipping = 6) at which mortality occurred or if they successfully hatched (7). * morttime2 - a text only version of the above "morttime" variable. The estimated embryonic developmental stage (very early, early, mid, late, very late, pipping) at which mortality occurred or if they successfully hatched * survival - whether the embryo died during development (1) or survived and successfully hatched (0). * survival2 - a text only version of the above "survival" variable. Whether the embryo died during development or survived and successfully hatched. * d4hr - the heart rate of embryos at day 4 of embryonic development (bpm). * d4time - the time (in seconds) and which the heart rate measurement was taken, starting when the egg was initially removed from the incubator. * d4incorder - the order in which the egg was removed from the incubator when heart rate measurements had to be recorded for multiple embryos. * d10hr - the heart rate of embryos late in embryonic development, measured on day 10 for embryos in the high temperature incubator and day 11 for embryos in the control temperature incubator (bpm). * d10time - the time (in seconds) and which the heart rate measurement was taken, starting when the egg was initially removed from the incubator. * d10incorder - the order in which the egg was removed from the incubator when heart rate measurements had to be recorded for multiple embryos. * d10mass - the egg mass late in development, recorded after heart rate measurements (g). * wtchange - the difference in mass (g) between the initial egg mass and the egg mass recorded later in development (day 10 or 11). * Hdate - egg hatch date. * Htime - egg hatch time (24 hour time). * inctime - the amount of time (in days) between the egg was laid and when it hatched. * Edate - hatchling euthanasia/dissection date. * Etime - hatchling euthanasia/dissection time (24 hour time). * Timebtw - the time (in minutes) between hatch and euthanasia/dissection. * body - hatchling total body mass (g). * pec - hatchling pectoralis mass (g). * yolk - hatchling residual yolk mass (g). ## Code/Software All statistical analyses were done using R version 4.2.3 "Shortstop Beagle" and RStudio version 2023.03.0.386 "Cherry Blossom".