An early-life survival and reproductive trade-off shapes selection on body size

Evolutionary trade-offs - opposing trait effects on total fitness via different fitness components - are likely to be widespread. Some key trade-offs are expected to be the result of chains of causation acting across an organism's lifetime. For example, a trait imparting reproductive benefits early in life may trade off against reduced survival to attain later-life reproductive opportunities. Tools in evolutionary quantitative genetics have recently been developed to formally characterise selection acting through different causal pathways throughout the life cycle and, therefore, to formally characterise evolutionary trade-offs. We use these methods to investigate a trade-off between early life reproduction and survival, and how that trade-off affects selection on body size in the Soay sheep population inhabiting St Kilda (Outer Hebrides, Scotland). We decompose and quantify the total effects of first-year female body mass on lifetime fitness, with particular attention to the effect of ..., , # An early-life survival and reproductive trade-off shapes selection on body size

Dataset DOI: [10.5061/dryad.44j0zpct6](10.5061/dryad.44j0zpct6)

## Description of the data and file structure

Four datasets have been made available:

(a) data_ewes1.csv: it comprises data for female Soay sheep lambs, and includes the variables used in the statistical models (twin, mass, pregnancy, survival, fyres, and slres.

(b) data_ewes_all_ages.csv: data used in Figure 2f. It includes information to derive survival curves of Soay sheep according to maternal age at conception.

(c) data_ped.csv: the pedigree used in model (1) and in section *Alternate formulations of the bivariate relationship between lamb mass and early pregnancy (bivariate formulation)*

(d) data_pop.csv: population density in the study site for the years 1995-2015.

### Files and variables

#### File: data_ewes1.csv

**Description:** 

##### Variables

* cohort: year of birth
* birth_month: month of birth
* death_year: year of de...,