DOI: 10.5061/dryad.4xgxd25mk
title: Dance or disappear: Strategic sexual signalling in female Peninsular rock agama

description: Sexual signalling has traditionally been studied in the context of male
 competition and female mate choice, with female signalling considered of
 limited consequence. However, there is growing evidence of extensive
 sexual signalling in females in a wide range of taxa. Here, we test how
 females strategize the use of sexual signals in a socially polygynous
 lizard, Psammophilus dorsalis. We evaluated key hypotheses for how females
 should modulate their signalling, focussing on male quality, mate
 availability and stage of the breeding season. We simulate male quality
 using artificial male models to individually tagged, and intensely
 monitored wild female lizards, measuring their strategic investment in
 sexual signalling. We found that females invest more in signalling towards
 high quality males and increased their investment towards the later part
 of the only breeding season. We demonstrate that, contrary to typical
 expectations in polygynous systems, females invest in costly sexual
 signals and adjust their use to maximise benefits and minimise costs. We
 argue that in spatially dispersed species, females may face limited access
 to high quality mates, favouring costly sexual signalling. Our findings
 underscore the need to reassess sexual selection frameworks across taxa,
 recognising female signalling as an active force in shaping mating
 dynamics.
description: <strong>Data collection</strong>
   To assess hypotheses for variation in
 sexual signalling in females, a field experiment was conducted. Male
 models of different colour states, representing two levels of male
 quality, were presented to tagged females on their territories.  Regular
 monitoring of the study population provided information on mate
 availability.  
 <strong>Model presentation
 experiment</strong>  
 Female signalling responses to potential mates were assessed
 through field experiments on individually tagged females. 3D printed
 models mimicking male lizards were painted in two different colour states
 chosen to represent male quality: yellow (low), and bright orange (high).
 Female lizards were presented with these models at different times during
 their breeding lifespan. During each trial, the behaviour of the female
 before and after the presentation of a model was recorded on a video
 camera mounted on a tripod. The video camera was placed at a distance of
 at least 15 metres from the focal lizard to avoid any disturbance to the
 focal lizard. The behaviour of the focal lizard was recorded for 15
 minutes. Next, a male model was carried towards the focal individual and
 placed on a perch at a distance less than 5 metres from the focal lizard.
 After placing the model on a perch where male lizards usually display, the
 observer returned back to the video camera. We began the trial  only when
 the focal lizard was in a position such that the model was in direct line
 of sight of the lizard. Observations of the focal lizard were carefully
 recorded on the video camera for a period of up to 30 minutes. Any adult
 conspecific lizard appearing within 5 m of the focal lizard during the
 experiment was noted. If the model or focal lizard was disturbed by other
 lizards in the area, then the trial was aborted. The order in which the
 models (orange, yellow) were presented to a tagged lizard was randomised.
 A gap of a minimum of 4 days was given between different model trials to
 avoid habituation to models by the focal lizard. There were at least two
 individual models printed and painted of each type to offset the effect of
 the model.  
 <strong>Assessing mate
 availability</strong>  
 To assess mate availability, lizards were followed and observed
 through regular surveys. The surveys involve the observer walking along a
 fixed path through the sheet rocks and making note of all the lizards in
 the study area. Tagged individuals can be identified with images shot from
 a camera without disturbing the lizard. The lizards were noted down onto a
 map, which was later geo-referenced to get the exact location of the
 lizard. Colour status of males and gravidity status of females was noted
 for each lizard. Each area was surveyed twice within the same session to
 maximise sightings, however only previously unrecorded tagged lizards were
 noted the second time to avoid duplicating records. The survey data on
 lizard distributions let us estimate mate availability.
   <strong>Data
 Analysis</strong>  
 Model presentation trials were transcribed using the software
 BORIS (Friard and Gamba, 2016).  
  An elaborate ethogram of all behaviours was created. We
 identified sexual signalling behaviours as those associated with courtship
 interactions from previous studies (Deodhar and Isvaran, 2018; R. S.
 Radder et al., 2006; Ranade, 2020), and ad-libitum observations of
 courtship behaviour in the field. The behaviours "crouch" and
 "tail-raise," along with the colour states "red-head"
 and "dark-body," (Fig:2, supplementary video) were further
 analysed as they were associated with sexual signalling. The behaviours
 are described in greater detail in the supplementary section. The analysis
 was carried out in R (Version 4.1.3)(Team, 2021).
   <strong>Measuring social
 condition of lizards</strong>  
 The spatial information from regular surveys was geo-referenced
 from maps with the help of Qgis software. The tagged female lizards we
 sampled through assays were followed through regular surveys. We
 considered survey data 30 days prior to the day of a trial to measure the
 provisional mate availability for the focal female for that trial. Females
 were usually recorded in multiple surveys over the 30 day window. To each
 spatially marked sighting of a focal female, we used a 20 m radius buffer
 (using gbuffer function in R, package rgeos) and recorded the number of
 males that were observed for each unique sighting of the focal female. The
 20 m was considered based on home range sizes from earlier studies. We
 measured the number of unique males each female was exposed to, in the
 30-day period before the assay. For each sighting of the female, in the
 surveys, we were able to assign a total number of males and since the
 males were tagged, we were able to identify the number of unique males a
 female was exposed to, and this was considered as a proxy for mate
 availability.  
 <strong>Breeding season</strong>
   The breeding season lasts from May
 till October. Trials were predominantly carried out between June and
 October. June and July were considered as early breeding season and August
 and September were considered late breeding season.
description: # Dance or disappear: Strategic sexual signalling in female Peninsular
 rock agama
 [https://doi.org/10.5061/dryad.4xgxd25mk](https://doi.org/10.5061/dryad.4xgxd25mk) ## Description of the data and file structure ### Files and variables #### File: behaviour\_data\_Procb.csv **Description:**  ##### Variables * lizard.id: Unique ID of lizard   * bead.code: Unique bead code for each lizard (Character that describes the colour of ceramic beads, example WWB mean white,white, blue in the order) * date: Date (%%dd%%mm%%yyyy) * model.id: Two colour states were presented - Orange and Yellow (denoted as ORM and YLM) * prop.redhead: Proportion of time spent in red-head colour state ;Range: 0 to 1 (Time spent in behavioural state/Total observation time) * prop.crouchposture: Proportion of time spent in crouch posture ;Range: 0 to 1(Time spent in behavioural state/Total observation time) * prop.tailraise: Proportion of time spent in tail raise posture ;Range: 0 to 1(Time spent in behavioural state/Total observation time) * prop.darkbody: Proportion of time spent in dark-body colour state ;Range: 0 to 1(Time spent in behavioural state/Total observation time) * nmal: Number of males in the 20 m vicinity within a 1 month period (This data was obtained from regular surveys. In each survey the number of male neighbours were calculated for every individual female and unique males were calculated for each female) * breeding: Categories - Early and late breeding season #### File: Behaviourdata\_mean\_CI.csv **Description:**  ##### Variables * Behaviour: The  four behaviours - Tail raise, crouch, red-head, dark-body * Model: Orange and yellow model representing colour states * mean: Mean * lower: Lower CI * upper: Upper CI ## Code/software We used R software. The workflow begins by loading the necessary libraries, `ggplot2` for visualization and `glmmTMB` for mixed-effects modeling. A cleaned behavioral dataset (`behaviour_data_Procb.csv`) is then imported, containing pre-filtered behaviors of interest. To estimate variability, a bootstrap function is defined and used to calculate 95% confidence intervals (CI) for `prop.tailraise` as an example, separately for the `YLM` and `ORM` models based on breeding status. Mean values of `prop.tailraise` as an example are also computed for each model. The same is done for each behaviour and saved in a CSV file (`Behaviourdata_mean_CI.csv`) and reloaded for visualization. A bar plot is created using `ggplot2`, displaying mean values with error bars representing CIs, styled for clarity. Since beta regression requires values between 0 and 1, any occurrences of `1` in `prop.tailraise` are replaced with `0.999`. Similar graphs were plotted for other behaviours and conditions. A zero-inflated beta regression model is then fitted to `prop.tailraise`, incorporating `model.id`, `nmal.cat`, and `breeding` as fixed effects, with `lizard.id` as a random effect. The same was done for prop.darkbody and prop.redhead.  Additionally, since `prop.crouchposture` is relatively rare, it is converted into a binary presence-absence variable, and a binomial mixed-effects model is fitted.  ## Access information Other publicly accessible locations of the data: * NA Data was derived from the following sources: * From data we collected in field