DOI: 10.5061/dryad.r4xgxd2h3
title: Female chacma baboons modulate their sexual receptivity in response to male intrasexual competition

description: Research in social mammals has revealed the complexity of strategies
 females use in response to female-female reproductive competition and
 sexual conflict. One point at which competition and conflict manifest
 acutely is during sexual receptivity, indicated by swellings in some
 primates. Whether females can adjust their sexual receptivity from cycle
 to cycle to decrease reproductive competition and sexual conflict in
 response to social pressures has not been tested. As a first step, this
 study explores whether sexual receptivity duration is predicted social
 pressures in wild female chacma baboons (Papio ursinus). Given that female
 baboons face intense reproductive competition and sexual coercion, we
 predicted that: females could shorten the duration of their sexual
 receptive period to reduce female-female aggression and male coercion or
 increase it to access multiple or their preferred male(s). We quantified
 157 ovulatory cycles from 46 wild females living in central Namibia
 recorded over 15 years. We found no support for our hypothesis; however,
 our analyses revealed a negative correlation between maximal-swelling
 duration and group size, a proxy of within-group competition. This study
 provides further evidence that swelling is costly as well as a testable
 framework for future investigations of ‘cycle length manipulation’.
description: Data were collected from identifiable females within two
 habituated groups, J and L, of a wild chacma baboon population at Tsaobis
 Leopard Park (22º22´S, 15º 44´E) in central Namibia. Studies on this
 population, which have been ongoing since 2000, have revealed that the
 naturally-foraging baboons exhibit low predation risk and high
 female-female aggression rates that can result in reproductive
 suppression. Over the course of the study, troop numbers fluctuated around
 a median of 55 (44–69) in J troop and 52 (21–71) in L troop. 
 The data used in this study were collected periodically over 15
 years, from 2005 to 2019, during field seasons lasting between 2 and 8
 months per annum, usually during the austral winter. During field seasons,
 troops were visited daily, when possible, with some interruptions for
 other tasks or unforeseen circumstances. During troop visits, we collected
 data on troop composition (see below) and individual behaviour ad
 libitum.  Individuals’ ages were known from observing
 births or from patterns of dentition wear following capture. Individuals’
 relative ranks were calculated annually from ad libitum recorded dominance
 interactions in the package Matman 1.1.4 (Noldus Information Technology,
 2013). Absolute ranks were converted to a relative scale ranging from 0
 (lowest rank) to 1 (highest rank), to control for group size, using the
 formula 1-((1-r)/(1-n)), with r being individual’s absolute rank ranging
 from 1 to the total group size n.  Methods for
 processing the data:  Each day that the troop was
 contacted, a census was completed that recorded the identities of the
 individuals present and the reproductive states of each adult female.
 Females’ reproductive states were recorded as: (1) pregnant (determined
 post hoc based on lack of resumption of swelling, reddening of the
 paracallosal skin and subsequent birth); (2) lactating (i.e., period
 following the birth of an infant until cycle resumption); (3)
 oestrous/swollen (i.e., exhibiting periovulatory swelling of the
 anogenital region); (4) non-swollen (i.e., deturgescent but not pregnant).
 For females in oestrus, we also recorded swelling size on a scale from 0.5
 (smallest) to 4 (largest), on an absolute (cf. the population) rather than
 relative (cf. for that particular female) scale.  As mentioned above,
 baboon troops were not followed daily, and as such there were some missing
 data during some females’ cycles. We discarded any observations where the
 start or end of the swelling duration was missing and thus could introduce
 inaccuracy.  For females in oestrus, swelling duration
 was calculated as the number of continuous days that a female was recorded
 with a swelling of any size. Because different mechanisms could act on the
 different parts of the cycle, in addition to swelling durations, we
 calculated the maximal-swelling duration as the number of days the focal
 female exhibited the largest swelling size during that respective cycle.
 We excluded from the initial data 8 observations of maximal-swelling
 duration which were calculated as 0, i.e., observations that showed that
 females were only swollen, and this resulted in 158 swellings and 158
 maximal-swellings from 47 females (median number of swellings / female =
 5, range = 1-14).  We calculated five variables
 describing aspects of the social environment relevant to our hypotheses:
 for H1, we calculated (1) the sum of pregnant and lactating females (“PL”)
 during the time a focal female was either swollen or maximally-swollen.
 For hypothesis H2a, we measured the number of other females that were (2)
 not maximally-swollen and (3) maximally-swollen, both when the focal
 female started swelling. To test hypothesis H2b and part of H2c, we
 calculated the (4) operational sex ratio (“OSR”) as the ratio of sexually
 active females (i.e., swollen at any level) to adult males. For H2c, we
 also calculated the (5) the number of in-group adult males.
description: All statistical analyses were performed using R (version 4.0.3,
 2020-10-10). Repeatability (R) was calculated using the rpt function (rptR
 package).
description: This readme file was generated on 27/08/2023 by Fragkiskos Darmis GENERAL
 INFORMATION Title of Dataset: Baboons\_complete Author Name: Fragkiskos
 Darmis ORCID: 0000-0002-1457-676X Institution: Max Planck Institute for
 Evolutionary Biology Address: August-Thienemann-Straße 2, 24306 Plön
 Email: darmis@evolbio.mpg.de Author Name: Alecia J. Carter ORCID:
 0000-0001-5550-9312 Institution: University College London Address: 14
 Taviton Street Kings Cross, WC1H 0BW, London Email:
 alecia.carter@ucl.ac.uk Author Name: Élise Huchard ORCID:
 0000-0002-6944-449X Institution: Institut des Sciences de L'Evolution
 de Montpellier, UMR 5554, CNRS, Université de Montpellier Address:
 1093-1317 Rte de Mende, 34090, Montpellier Email:
 elise.huchard@umontpellier.fr Author Name: Guy Cowlishaw ORCID:
 0000-0002-7269-4625 Institution: Institute of Zoology, Zoological Society
 of London Address: Zoological Society of London, Regent's Park,
 NW14RY Email: guy.cowlishaw@ioz.ac.uk Date of data collection: 2005-2019
 Geographic location of data collection: Tsaobis Leopard Park (22º22´S, 15º
 44´E) in central Namibia Information about funding sources that supported
 the collection of the data: Long-term data collection was partially funded
 by grants from: the Agence Nationale de la Recherche (ANR
 ERS-17-CE02-0008, 2018-2021) awarded to EH; a Fenner School of Environment
 and Society Scholarship awarded to A.J.C., a Ministère de l’Education et
 de la Recherche Studentship awarded to E.H; a NERC Advanced Research
 Fellowship awarded to G.C.; Leakey Foundation grants awarded to AJC; and a
 Templeton World Charity Foundation grant (TWCF0502) awarded to AJC. This
 paper is a contribution ISEM (n° TBD) and a publication of the ZSL
 Institute of Zoology’s Tsaobis Baboon Project, supported by Research
 England. SHARING/ACCESS INFORMATION Licenses/restrictions placed on the
 data: - Links to publications that cite or use the data: - Links to other
 publicly accessible locations of the data: - Links/relationships to
 ancillary data sets: - Was data derived from another source? If yes, list
 source(s): - Recommended citation for this dataset: Baboons\_complete DATA
 & FILE OVERVIEW File List: Baboons\_complete Relationship between
 files, if important: - Additional related data collected that was not
 included in the current data package: - Are there multiple versions of the
 dataset? If yes, name of file(s) that was updated: - Why was the file
 updated? When was the file updated? METHODOLOGICAL INFORMATION Description
 of methods used for collection/generation of data: Data were collected
 from identifiable females within two habituated groups, J and L, of a wild
 chacma baboon population at Tsaobis Leopard Park (22º22´S, 15º 44´E) in
 central Namibia. Studies on this population, which have been ongoing since
 2000, have revealed that the naturally-foraging baboons exhibit low
 predation risk and high female-female aggression rates that can result in
 reproductive suppression. Over the course of the study, troop numbers
 fluctuated around a median of 55 (44–69) in J troop and 52 (21–71) in L
 troop. The data used in this study were collected periodically over 15
 years, from 2005 to 2019, during field seasons lasting between 2 and 8
 months per annum, usually during the austral winter. During field seasons,
 troops were visited daily, when possible, with some interruptions for
 other tasks or unforeseen circumstances. During troop visits, we collected
 data on troop composition (see below) and individual behaviour ad libitum.
 Individuals’ ages were known from observing births or from patterns of
 dentition wear following capture. Individuals’ relative ranks were
 calculated annually from ad libitum recorded dominance interactions in the
 package Matman 1.1.4 (Noldus Information Technology, 2013). Absolute ranks
 were converted to a relative scale ranging from 0 (lowest rank) to 1
 (highest rank), to control for group size, using the formula
 1-((1-r)/(1-n)), with r being individual’s absolute rank ranging from 1 to
 the total group size n. Methods for processing the data: Each day that the
 troop was contacted, a census was completed that recorded the identities
 of the individuals present and the reproductive states of each adult
 female. Females’ reproductive states were recorded as: (1) pregnant
 (determined post hoc based on lack of resumption of swelling, reddening of
 the paracallosal skin and subsequent birth); (2) lactating (i.e., period
 following the birth of an infant until cycle resumption); (3)
 oestrous/swollen (i.e., exhibiting periovulatory swelling of the
 anogenital region); (4) non-swollen (i.e., deturgescent but not pregnant).
 For females in oestrus, we also recorded swelling size on a scale from 0.5
 (smallest)-4 (largest), on an absolute (cf. the population) rather than
 relative (cf. for that particular female) scale. As mentioned above,
 baboon troops were not followed daily, and as such there were some missing
 data during some females’ cycles. We discarded any observations where the
 start or end of the swelling duration was missing and thus could introduce
 inaccuracy. For females in oestrus, swelling duration was calculated as
 the number of continuous days that a female was recorded with a swelling
 of any size. Because different mechanisms could act on the different parts
 of the cycle, in addition to swelling durations, we calculated the
 maximal-swelling duration as the number of days the focal female exhibited
 the largest swelling size during that respective cycle. We excluded from
 the initial data 8 observations of maximal-swelling duration which were
 calculated as 0, i.e., observations that showed that females were only
 swollen, and this resulted in 158 swellings and 158 maximal-swellings from
 47 females (median number of swellings / female = 5, range = 1-14). We
 calculated five variables describing aspects of the social environment
 relevant to our hypotheses: for H1 we calculated (1) the sum of pregnant
 and lactating females (“PL”) during the time a focal female was either
 swollen or maximally-swollen. For hypothesis H2a, we measured the number
 of other females that were (2) not maximally-swollen and (3)
 maximally-swollen, both when the focal female started swelling. To test
 hypothesis H2b and part of H2c, we calculated the (4) operational sex
 ratio (“OSR”) as the ratio of sexually active females (i.e., swollen at
 any level) to adult males. For H2c, we also calculated the (5) the number
 of in-group adult males. We have also calculated group size, the number of
 adults and subadults in each troop, to test if Instrument- or
 software-specific information needed to interpret the data: All
 statistical analyses were performed using R (version 4.0.3, 2020-10-10).
 Repeatability (R) was calculated using the rpt function (rptR package),
 Standards and calibration information, if appropriate: -
 Environmental/experimental conditions: - Describe any quality-assurance
 procedures performed on the data: - People involved with sample
 collection, processing, analysis and/or submission: Past Tsaobis Baboon
 Project leaders, students, volunteers and interns contributed to the
 long-term data collection at the field site. AJC, EH and FD contributed to
 the conceptualization. AJC and EH designed the study. GC established the
 study system and oversaw data collection, with assistance from AJC and EH.
 FD performed the statistical analyses. All authors contributed to draft
 the manuscript. DATA-SPECIFIC INFORMATION FOR: Baboons\_complete Number of
 variables: 18 Number of cases/rows: 158 Variable List: * ID: The
 individual ID of a female, here a number is used to indicate it. * troop:
 The troop to which a female belonged during the observation, with three
 troops being recorded (M, J, L). * so\_date: The date the focal female
 started swelling. * state: The size of the swelling at the start of the
 swelling period. * mxm\_sw\_dur: The number of days the focal oestrous
 female exhibited the largest swelling size during that respective cycle. *
 sw\_dur: For females in oestrus, swelling duration was calculated as the
 number of continuous days that a female was recorded with a swelling of
 any size. * not\_mxm\_sw\_fem: The number of other females that were not
 maximally-swollen when the focal female started swelling. * mxm\_sw\_fem:
 The number of other females that were maximally-swollen when the focal
 female started swelling. * p\_females: The number of pregnant females
 during the time a focal female was either swollen or maximally-swollen. *
 l\_females: The number of lactating females during the time a focal female
 was either swollen or maximally-swollen. * p\_l: The sum of pregnant and
 lactating females during the time a focal female was either swollen or
 maximally-swollen. * cycling\_females: The number of females that were
 cycling (i.e., not pregnant or lactating) but not swollen. * group\_size:
 The total number of individuals of any age in the troop. * adult\_males:
 The number of adult males in the troop of the focal female during the time
 of observation. * age: The age of the focal female, measured in years. *
 relative\_rank: The relative rank of the focal female compared to other
 females of the troop at the time of observation. The relative scale ranged
 from 0 (lowest rank) to 1 (highest rank), and was created using the
 formula 1-((1-r)/(1-n)), with r being individual’s absolute rank ranging
 from 1 to the total group size n. * sw\_females: The number of other
 females that were swollen at any stage (maximally and non-maximally) when
 the focal female started swelling. * OSR\_(f/m): The number of sexually
 receptive females to the number of adult males. Missing data codes: NA
 (data not available / not applicable) Specialized formats or other
 abbreviations used: -