DOI: 10.5061/dryad.dz08kps30
title: Data from: Sex bias in mortality risk changes over the lifespan of bottlenose dolphins

description: Research on sex biases in longevity in mammals often assumes that male
 investment in competition results in a female survival advantage that is
 constant throughout life. We use 35 years of longitudinal data on 1,003
 wild bottlenose dolphins (Tursiops aduncus) to examine age-specific
 mortality, demonstrating a crossover effect of sex on mortality hazard
 over the five-decade lifespan of a social mammal. Males are at higher risk
 of mortality than females during the juvenile period, but female mortality
 hazard begins to exceed male mortality hazard in the mid-teens, coincident
 with the onset of female reproduction. Female mortality hazard remains
 higher than male hazard throughout most of adulthood. Bottlenose dolphins
 have an intensely male-competitive mating system, and juvenile male
 mortality has been linked to social competition. Contrary to predictions
 from classical sexual selection theory, however, male-male competition
 does not result in sustained male-biased mortality. As female dolphins
 experience high costs of sexual coercion in addition to long and
 energetically expensive periods of gestation and lactation, this suggests
 that substantial female investment in reproduction can elevate female
 mortality risk relative to males in adulthood.
description: # Sex bias in mortality risk changes over the lifespan of bottlenose
 dolphins ## Description of the data and file structure This file explains
 all of the variables in each of the datasets that accompany: McEntee,
 M.H.F., Foroughirad, V., Krzyszczyk, E., Mann, J. 2023. Sex bias in
 mortality risk changes over the lifespan of bottlenose dolphins. For more
 information please contact Molly McEntee at
 [mhm95@georgetown.edu](mailto:mhm95@georgetown.edu). ### Files and
 variables #### File: lifespan_data.csv **Description:** data to produce
 Kaplan-Meier plots, Cox proportional hazards analysis, PAM analysis, and
 sensitivity analysis. ##### Variables * Dolphin.ID = dolphin ID *
 Birth.Date = date of dolphin birth (YYYY-MM-DD) * Death.Date = date of
 dolphin death if known (YYYY-MM-DD), NA if the dolphin is alive * Sex =
 Female, Male, or Unknown * total.num.sightings = Total number of sightings
 of that dolphin in the dataset * gap = maximum individual sighting gap
 (years), NA if the individual occurred one time or fewer in the data. *
 time = time at death if dead, time at right censorship if alive (years) *
 event = 1 if dead, 0 if alive * trunc.time = age the dolphin entered the
 dataset (years) * first.sight.date = first occurrence of the dolphin in
 the dataset (YYYY-MM-DD) * last.sight.date = last occurrence of the
 dolphin in the dataset (YYYY-MM-DD) #### File: BaSTA_data.csv
 **Description:** data used for BaSTA analysis. This is mark-recapture data
 for the same juvenile and adult sample as the lifespan data. #####
 Variables * ID = dolphin ID * Birth = year of birth, 0 if unknown. In this
 analysis we blinded the model to year of birth, so all values are 0. *
 Death = year of death, 0 if unknown. In this analysis we blinded the model
 to year of death, so all values are 0. * 1985-2019 = 1 if the dolphin was
 seen in that year, 0 if the dolphin was not seen in that year * SexFemale
 = 1 if the dolphin is female, 0 if the dolphin is male * SexMale = 1 if
 the dolphin is male, 0 if the dolphin is female ## Code/software ####
 File: R.code.Lifespan.R Code to reproduce all figures in R. ###