Sexual selection on a female copulatory device in an insect with nuptial gifts
Data files
Dec 11, 2023 version files 85.68 KB
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Bateman_data.xlsx
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Genetic_data.xlsx
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README.md
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Sexual_selection.xlsx
Abstract
Male genitalia are rapidly evolving structures, often driven by sexual selection to increase fertilization success. Although sexual selection on females can be strong in systems where males provide offspring care or feed their mates, sometimes resulting in the evolution of female ornamentation, there are no actual estimates of direct sexual selection on female genitalia. In a New Zealand ground weta, Hemiandrus pallitarsis (Orthoptera: Ensifera, Anostostomatidae), females possess a genitalic device (the accessory organ) that is necessary for successful copulation and the acquisition of glandular food-gifts from males. These nutritious gifts are known to result in sexual competition among females in other ensiferan species. In ground weta, the gifts are probably important in avoiding starvation during a months-long period when caring for (their lifetime production of) eggs and offspring. Here, we test the hypothesis that the accessory organ is a sexually selected device in H. pallitarsis by measuring the female Bateman gradient, Jones index, and directional sexual selection on the accessory organ. Using newly developed and characterized microsatellite loci, we analyze offspring and/or stored sperm to estimate female mating frequency for the first time in ground weta. As predicted, we found both a positive Bateman gradient and Jones index for females, and evidence of directional sexual selection on accessory organ length. Although organ length does not correlate well with female fecundity, it may increase mating success by indicating her condition and thus quality of her offspring care.
README
Genetic data.xlsx
Includes multiple sheets containing all genetic data:
-Sheet "population genotypes" contains all genotypes from our two collection sites, used to characterize loci (Genepop 4.7; results included in ESM 1) and to inform parentage analyses (Software GERUD).
-Sheets "KA", "KB", "PA", "PB", "PC", "PD", "PE", "PF", "K2A", "K2D", "K2E", "K2G", "K2J", "P2B", "P2C", "P2E", and "P2G" each represent a different weta family and contain Genotypic data for offspring, their mother, and one potential father, the "last male". These data were used to estimate female mating success (using GERUD to detect discrete sires) for Bateman gradients and Jones index.
In the above sheets, data are provided per specimen in rows, with separate columns for microsatellite loci, each containing 2 alleles. Alleles are shown as 3-digit numbers which represent the lengths (number of base pairs) of the DNA fragments. Samples beginning with "K" or "W" were collected from Kiriwhakapapa and samples beginning with "P" or "N" were collected from Palmerston North. "null" indicates undetected alleles.
-Sheet "Sperm stores_bateman" contains the alleles detected in the stored sperm of females at each locus. Used to estimate female mating success for measures of Bateman gradients and Jones index (in combination with offspring data).
-Sheet "Sperm stores_accessory organs" contains the alleles detected in the stored sperm of females at each locus. Used to estimate female mating success for directional selection on accessory organs.
In the above sheets, data are provided per specimen in rows, with separate columns for collection location and microsatellite loci, each containing 1-10 alleles. Alleles are shown as 3-digit numbers which represent the lengths (number of base pairs) of the DNA fragments. "null" indicates undetected alleles.
Bateman_data.xlsx
Includes data for all analyses and figures (Figure 3) regarding the Bateman gradient and Jones Index. Size was determined by measuring the length of the pronotum, Number of offspring (total and developed) were counted and estimates of mating success (number of mates) were obtained from genotypic data of offspring and stored sperm.
-Sheet "bateman" contains all data used to calculate pooled Bateman gradients and Jones Index.
-Sheet "bateman02" contains data used to calculate Bateman gradients for the year 2002.
-**Sheet "Bateman17" contains data used to calculate Bateman gradients for the year 2017.
In all sheets, each row contains a specimen with columns showing: Collection year, collection location (K indicates Kiriwhkapapa; PN indicates Palmerston North), body size (pronotum length; in mm), and our two measures of reproductive success. Any blank cells indicate missing data, and must be left empty to facilitate standardization of data. R code is set up to calculate relative (mean-standardized) values for body size, mating success, and both measures of reproductive success in Columns 8-11, therefore "TBD" is used as a place holder.
Sexual_selection.xlsx
-Sheet “females.ss” includes phenotypic data used to measure directional sexual selection on accessory organs (estimates of mating success determined from alleles found in stored sperm) and the relationship between accessory organs and fecundity (number of eggs in the abdomen).
Each row contains a specimen with columns showing: Collection location (K indicates Kiriwhkapapa; PN indicates Palmerston North), Collection year, body size (pronotum length; in mm), accessory organ length (in mm), accessory organ width (in mm), and mating success, and fecundity. Any blank cells indicate missing data, and must be left empty to facilitate standardization of data (as per R code).
R_code_acessory_organs.R
Includes the script for all analyses and graphs included in the article:
Female Bateman gradients contains code used to determine Bateman gradients (linear regression of mating success and reproductive success), using total eggs laid and those that developed to the nymphal stage. Next is the analysis of bateman gradients that include body size as well as interactions with collection site and year. Next is code used to make Figure 3 displaying bateman gradients. Uses datafile “bateman”. Next are Bateman gradients separated by collection year for both measures of reproductive success. Uses datafiles “bateman02” and “bateman17”
Jones Index contains calculations for Jones Index (also determined using Batemanator). We first calculate the variance in relative mating success and then multiply this by each bateman gradient (regression coefficient of mating success and reproductive success) to determine the Jones index. Uses datafile “bateman”.
Sexual selection on accessory organs contains all code used to measure sexual selection on accessory organs (multiple linear regression of accessory organ traits and mating success). It includes the MLS regression model reported in the text as well as a linear mixed model which includes site as a random effect (singular fit). Next are graphs used to visualize differences between collection sites, and regression models that test for an interaction with each of our trait variables. Next are plots for each trait that display variation between sites (included in ESM 1). Uses datafile “females.ss”
Relationship with number of eggs contains all code used to measure the relationship between accessory organs and fecundity (multiple linear regression of accessory organ traits and number of eggs in the abdomen). It includes an MLS regression model as well as the linear mixed model reported in the text (site as a random effect). Next are graphs used to visualize differences between collection sites, and regression models that test for an interaction with each of our trait variables. Next are plots for each trait that display variation between sites (included in ESM 1). Uses datafile “females.ss”
Usage notes
Excel, R studio