DOI: 10.5061/dryad.83bk3jb1g
title: The transfer of male cuticular hydrocarbons provides a reliable cue of the risk and intensity of sperm competition in decorated crickets

description: Theoretically, males should increase their ejaculate expenditure when the
 probability of sperm competition occurring (or risk) is high but decrease
 ejaculate expenditure as the number of competing ejaculates (or intensity)
 increases. Here we examine whether male decorated crickets (Gryllodes
 sigillatus) use cuticular hydrocarbons (CHCs) transferred to females by
 rival males at mating to assess the risk and intensity of sperm
 competition and adjust their ejaculate accordingly. Unmated females and
 those perfumed with CHCs extracted from one, three or five males could be
 distinguished chemically, providing a reliable cue of the risk and
 intensity of sperm competition. In agreement with theory, males mating to
 these females increased sperm number with the risk of sperm competition
 and decreased sperm number with the intensity of sperm competition.
 Similarly, as the risk of sperm competition increased, males produced a
 larger and more attractive spermatophylax (an important non-sperm
 component of the ejaculate) but there these traits did not vary with the
 intensity of sperm competition. Our results therefore demonstrate that
 both sperm and non-sperm components of the male ejaculate respond to the
 risk and intensity of sperm competition in different ways and that CHCs
 provide males with an important cue to strategically tailor their
 ejaculate.
description: In Experiment 1, we collected the cuticular hydrocarbon (CHC)
 profiles of virgin females that had been perfumed with the CHCs of one
 male, three males and five males, as well as virgin males and virgin
 females that were not perfumed. We determined the CHC of crickets in these
 treatments using established GC-MS protocols for this species
 (<em>Gryllodes sigillatus</em>). This experiment showed that
 the CHC profile of crickets in these treatments could be statistically
 distinguished and therefore provide a reliable cue for the risk and
 intensity of sperm competition. In Experiment 2, we
 applied these same perfuming treatments to females (virgin female -
 control, one male, three males and five males) and then allowed them to
 mate with a naive virgin male. We measured each males sperm count using
 microscopy. We also measure the dry weight of the spermatophylax (using an
 electronic balance) and the attractiveness of the spermatophylax based on
 the free amino acid composition. We determined the free amino acid
 composition of the spermaotphylax using established GC-MS protocols for
 this species.
description: # The transfer of male cuticular hydrocarbons provides a reliable cue of
 the risk and intensity of sperm competition in decorated crickets This
 publications consists of two experiments. In Experiment 1, we perfumed
 virgin females with the cuticular hydrocarbons (CHCs) of one male, three
 males, five males and measured their CHC profile using GC-MS. We also
 measured CHCs in a sample of virgin males and virgin females. We used
 discriminant function analysis to show that the CHC profile of crickets in
 these treatment groups could be statistically distinguished and therefore
 provide a male cricket with information on the risk and intensity of sperm
 competition. In Experiment 2, we applied these same perfuming procedures
 (no perfuming - control, one male, three males and five males) to virgin
 females and then allowed them to mate to a naive and virgin male. For each
 male, we measure their sperm count (using microscopy), dry weight of the
 spermatophylax (using an electronic balance) and the multivariate
 attractiveness of the spermatophylax based on the free amino acid
 composition (using GC-MS). ## Description of the data and file structure
 Microsoft Excel is required to open the data files. We have uploaded 2
 files: named "Dryad_Experiment 1" and "Dryad_Experiment
 2". "Dryad_Experiment 1" contains all of the raw data for
 Experiment 1. The first column ("Treatment") contains the
 treatment group (virgin_female, virgin_male, one_rival, three rivals and
 five rivals). Column 2 ("Code") contains the unique numerical
 code used in a discriminant function analysis. Columns 3 to 17
 (**"Peaks 1 to 15", each peak is the area under the peak that
 characterizes one chemical (CHC)**) contain the abundance of each CHC peak
 (full names provided in Table 1 of the manuscript). Columns 18 to 20
 ("DF1, DF2 and DF3" - **discriminate functions do not have
 units**) contain the saved discriminant functions (with eigenvalues
 exceeding 1) on these 15 CHC peaks. "Dryad_Experiment 2"
 contains all of the raw data for Experiment 1. The first column
 ("Treatment) contains the treatment group (control, one_rival,
 three_rivals and five_rivals). The second column ("PW") contains
 the pronotum width of males (measured in **mm** using an eyepiece
 graticule in a dissecting microscope). The third column
 ("Sperm_count") contains the **number of sperm** contained in
 the male's ampulla (measured using a compound microscope). The fourth
 column ("SPHYLAX_DW") contains the dry weight of the
 spermatophylax (**ng**, measured after freeze drying using an electronic
 balance). The final column ("SPHYLAX_Attractiveness") is the
 multivariate attractiveness score of the spermatophylax (**there are no
 units of measurement as it is derived from a vector of linear selection
 gradients**) based on the free amino acid composition (determined using
 GC-MS). ## Sharing/Access information Links to other publicly accessible
 locations of the data: The data contained on Dryad will be also be made
 publically available via the Research Data Management System at Western
 Sydney University. Data was derived from the following sources: All
 uploaded data has been collected from experiments conducted by the
 authors. ## Code/Software R code is provided for the permutation based
 MANCOVA. All other analyses were conducted using IBM SPSS (version
 29.0.0.0).