Sex bias in mortality risk changes over the lifespan of bottlenose dolphins

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 do..., , , # 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 [[e-mail]](mailto:[e-mail]).

### 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 indiv...,