Female biased offspring sex ratios of eastern wild turkeys across the southeastern United States
Data files
Aug 14, 2025 version files 222.41 MB
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All_Eggshells_SexID_10.csv
41.15 KB
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Dryad_GPS_Data_FemalE_010925.csv
222.36 MB
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OSR_Code.R
11.70 KB
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README.md
2.42 KB
Abstract
Prevailing theory suggests that sex ratios of offspring at birth should not differ from parity if costs of producing offspring of both sexes are similar. However, offspring sex ratios may deviate from parity when there is sex specific variation in fitness returns. We assessed offspring sex ratios of eastern wild turkeys (Meleagris gallopavo silvestris) across the southeastern United States by molecular determination of sex from eggshell membranes of hatched clutches. Our objective was to evaluate whether offspring sex ratios differed from parity and to examine potential drivers of variation in offspring sex ratios across and within our study sites. We sexed 724 offspring from 83 nests using molecular markers and identified 278 males and 446 females, with a sex ratio of 38% male. We found that offspring sex ratios were biased towards females on 3 hunted study sites but did not differ from parity at our remaining non-hunted site. Specifically, on sites with spring hunting, where male mortality was increased due to harvest, the probability of producing male offspring was 47% lower than on our non-hunted site. Our findings suggest that female wild turkeys may adaptively adjust the sex ratio of their offspring based on predictable, sex specific mortality, favoring the sex with higher survival, thereby enhancing their lifetime fitness. Our results provide insights into reproductive strategies of wild turkeys and the influence of hunting on sex ratios in Galliform offspring.
Dataset DOI: 10.5061/dryad.rr4xgxdm0
Description of the data and file structure
Analysis of offspring sex ratios of eastern wild turkeys by molecular determination of sex from eggshell membranes of hatched clutches.
Files and variables
File: OSR_Code.R
Description: R code for offspring sex ratio analysis and hidden markov model
File: All_Eggshells_SexID_10.csv
Description: input for offspring sex ratio analysis
Variables
- ID: unique identifier for each nest offspring belonged to
- clientSampleid: unique identifier for each offspring
- Sex: sex of offspring, either male (1) or female (0)
- State: state where nests were located
- Site: study site where nests were located
- SRS = Savannah River Site
- GA = Georgia
- WLA = west Louisiana
- SELA = southeast Louisiana
- Year: year of which collection occurred
- age: Age of incubating mother, either juvenile (0) or adult (1)
- Date_Laying: Date that the nest was initiated
- Total_Offspring: clutch size of nest
- Hunted_Site: indicates if nest was located on a hunted site (1) or non-hunted site (0)
- BehaviorState1.2: percentage spent in combined stationary and restricted behavioral state
File: Dryad_GPS_Data_FemalE**_**010925.csv
Description: input for Hidden Markov Model analysis
Variables
- X: number of entries
- DOP: dilution of precision for GPS locations
- Lat: Latitude of GPS locations
- Longitude: Longitude of GPS locations
- Site: study site for each individual
- GMT_Time: Greenwhich Mean Time for GPS location
- GMT_Date: Greenwich Mean Time of date for GPS location
- LMT_Date: Local Mean Time of date for GPS location
- LMT_Time: Local Mean Time for GPS location
- ID: Unique identifier for each female
- Phase: Reproductive phase for each female
- Year: Year of gps data collection
- DateTime: Local Mean Time and Date in mm/dd/yyyy H:M format
Code/software
RStudio
packages:
library(ggplot2)
library(tidyverse)
library(tidyr)
library(dplyr)
library(lubridate)
library(lme4)
library(bayestestR)
library(pROC)
library(easystats)
library(brms)
library(sf)
library(dplyr)
library(splitstackshape)
library(momentuHMM)
library(adehabitatLT)
library(lubridate)
library(readr)
library(stringr)
library(hms)