DOI: 10.5061/dryad.7d7wm3868
title: A family history: Effects of parental age on offspring life-history traits in bighorn sheep

description: Long-term fitness effects of parental age could affect population
 dynamics, as age structure can vary considerably over time. Few studies of
 wild animals, however, have examined the possible long-term fitness
 consequences of parental age. Based upon 50 years of data on wild bighorn
 sheep, we investigated how parental age affected three offspring traits –
 mass at three years, longevity, and female lifetime reproductive success.
 We also tested for a survival filter which could mask or increase fitness
 effects of parental age. Our results showed a significant, quadratic
 negative association between maternal age, offspring longevity and female
 lifetime reproductive success. Offspring born to mothers aged 5-6 years
 lived about 2 years longer and weaned about 1.5 lambs more than siblings
 born to mothers aged 12-13 years. The effect of paternal age was not
 significant. There was also a positive association between the longevity
 of mothers and offspring. We did not detect any effects of parental age on
 mass at three years for offspring of either sex. These results demonstrate
 the presence of persistent maternal age effects in a long-lived species.
 The sex-specific effects support the importance of analyzing maternal and
 paternal age effects separately, as well as effects on female and male
 offspring. This study advances our understanding of evolutionary processes
 and population dynamics in wild long-lived mammals.
description: # A family history: Effects of parental age on offspring life-history
 traits in bighorn sheep Dataset DOI:
 [10.5061/dryad.7d7wm3868](10.5061/dryad.7d7wm3868) ## Description of the
 data and file structure This dataset contains information on individual
 sheep, including their ID, sex, mass at 3 years old, birth and death
 years, parental information, and reproductive traits. ### Files and
 variables #### File: dataLongevityDad.csv **Description:** This dataset
 contains information on **offspring longevity** in relation to **paternal
 age and longevity**. It includes details on the focal individual's
 birth and death years, parental identifiers, and the number of adult
 females in the population. ##### Variables * ID: Unique identifier for
 each sheep. * idSex: Sex of the focal individual (*F * for female, *M* for
 male). * idLongevity: Longevity, in years, of the focal individual (the
 offspring). * birthYear: Year the individual was born (the cohort). *
 deathYear: Year the individual died (corresponding to the last sighting).
 * mumID: Unique identifier for the individual's mother (dam). *
 dadID: Unique identifier for the individual's father (sire). *
 dadLongevity: Total lifespan of the father (years). * dadAgeAtConception:
 Age (years) of the father at the time of offspring conception (also simply
 dadAge in some analyses). * fem: Number of females **older than 2 years**
 in the population. #### File: dataLongevityMum.csv **Description:** This
 dataset is structured similarly to `dataLongevityDad.csv`, but focuses on
 **maternal age and longevity effects** on offspring longevity. It includes
 additional variables specific to the mother. ##### **Additional Variables
 (not in `dataLongevityDad.csv`):** * **mumAge**: Age, in years, of the
 mother at the time of **offspring birth**. * **mumLongevity**: Total
 lifespan of the mother (years). #### Files: dataMassDad.csv and
 dataMassMum.csv **Description:** These datasets contain information used
 for **mass analyses**. All variables, except the following, are defined
 consistently with the previous datasets. The data are divided into
 **father** and **mother** files, focusing on paternal and maternal
 influences on the offspring’s mass. **Variables:** * **massAt3yoFall**:
 Body mass, in kg, of the offspring measured in the fall of their third
 year. * **fem3yo**: Number of females **older than 2 years** in the
 population when the offspring was 3 years old. #### Files: dataLRSMum.csv
 and dataLRSDad.csv **Description**: These datasets are used for analyzing
 **lifetime reproductive success (LRS)** in relation to **parental age and
 longevity**. The datasets are divided based on whether the focus is on
 **maternal** or **paternal** effects on offspring LRS. All other variables
 are defined consistently with previous datasets. ##### Variables *
 nbLbWeaned: The number of lambs successfully **weaned** by the focal
 individual (offspring); this variable is recorded **for females only**. *
 nbLbProduced: The total number of **lambs born** to the focal individual
 (offspring), regardless of survival; this variable is recorded **for
 females only**. * **Note:** For paternal LRS, we retained the full
 dataset, including missing values marked as 'NA', because the
 reproductive success of males (fathers) is less completely documented than
 that of females (mothers). ## Code/software Microsoft Excel, Numbers,
 LibreOffice.