DOI: 10.5061/dryad.5mkkwh7cv
title: Data from: incubation as a driver of maternal effects: temperature influences levels of yolk maternally derived 5α-dihydrotestosterone

description: In birds, maternal hormones deposited into eggs in response to
 environmental stimuli can impact offspring phenotype. Although less
 studied, environmental conditions can also influence females’ incubation
 behavior, which might play a role in regulating embryo exposure to
 maternal hormones through changes in incubation temperature that affect
 the activity of the enzymes responsible for converting testosterone (T) to
 5α-dihydrotestosterone (DHT) or estradiol. Here, we tested the hypothesis
 that the initial T content of the yolk and incubation temperature
 determine exposure to T metabolites during early embryo development. In
 the Japanese quail (Coturnix japonica), we experimentally manipulated yolk
 T and incubation temperature (38° C versus 36° C) and analyzed DHT and
 estradiol titers on day four of  incubation. We found that eggs
 with experimentally increased T and those incubated at 36° C showed higher
 DHT concentration in egg yolk (with no synergistic effect of the two
 treatments). Estradiol titers were not affected by T manipulation
 or incubation temperature. Our study suggests that incubation temperature
 influences DHT titers and may act as an understudied source of maternal
 influence on offspring phenotype.
description: Data were collected under an experimental setting in captivitity
 conditions. Eggs from 29 Japanise quail females were individually marked
 and weighed with a digital balance (± 0.1 g). Same clutch eggs were
 randomly assigned to treatments, in a full factorial 2 × 2 design:
 increased-T eggs incubated at 38° C (n = 40 eggs from 20 clutches),
 increased-T eggs incubated at 36° C (n = 42 eggs from 26 clutches),
 control eggs incubated at 38° C (n = 39 eggs from 21 clutches), and
 control eggs incubated at 36° C (n = 40 eggs from 21 clutches). During the
 first day of incubation 82 eggs were injected with 25 ng of T (increased-T
 eggs) diluted in 10 μL sesame oil. The amount of testosterone injected was
 within the natural range of variation reported for this species (4-30 ng/g
 of yolk). Seventy-nine eggs were injected with only 10 μL sesame oil. The
 injection site was sealed with surgical glue. On day
 four of incubation, a yolk biopsy of 80 μL (&lt; 5% of total yolk
 volume) was taken from all eggs to quantify hormone concentration
 (testosterone, estradiol and DHT). Yolk samples were diluted in 100 μL
 deionized water and frozen at -80° C until hormone analyses. After biopsy,
 eggs continued with the assigned incubation treatment until
 hatching.
description: # Incubation as a driver of maternal effects: Temperature influences
 levels of yolk maternally derived 5α-dihydrotestosterone
 ## Description of the data
 and file structure | Column | Variable type | Value | Unit | Explanatation
 | | ------------ | ------------- | ------------------- |
 -------------------- |
 ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | egg\_id | Numerical | | | Sample egg identity | | biopsy\_id | Numerical | | | Identity of biopsy sample  taken at 4 days of incubation  | | inc\_temp | Factor | 36/38 | degree Celsius (° C) | Incubation temperature | | t\_treat | Factor | Increased-T/Control | | Yolk testosterone manipulation | | female\_id | Numerical | | | Identity of female that laid each egg | | log\_horm | Numerical | | pg hormone/mL yolk | Hormone concentration in yolk transformed to logarithm | | laying\_date | Numerical | | Julian days | Laying date  | | egg\_mass | Numerical | | grams | Egg mass | | embryo | Binomial | 1/0 | Presence/absence | Presence or absence of developing embryo through observation of egg vascularization or the beating heart at 4 days of incubation or examining the egg 3 days after estimated hatching date | | inc\_batch | Factor | 1-3 | | Incubation batch | T= Testosterone E= Estradiol DHT= 5α-Dihydrotestosterone Missing data code: NA