Skip to main content
. 2017 Oct 30;114(45):E9753. doi: 10.1073/pnas.1717717114

Table 1.

Loadings of the life-history traits grouped by their relation to turnover, and strategies to longevity, growth, and reproduction onto the first two PCA axes

Life-history trait Symbol Definition PCA 1 PCA 2
Turnover T Number of years necessary for the individuals of a population to be fully replaced by new ones 0.85 0.17
 Generation time
Longevity H Shape of the age-specific survivorship curve lx as quantified by Keyfitz’ entropy (H). H <1, =1, >1 correspond to survivorship curves types I, II and III, respectively 0.55 0.23
 Survivorship curve type
 Age at sexual maturity Lα Number of years that it takes an average individual in the population to become sexually reproductive 0.71 0.29
Growth γ Mean probability of transitioning to a larger/more developed stage in the life cycle of the species, weighted by the stable stage distribution (SSD) −0.73 −0.05
 Progressive growth
 Retrogressive growth ρ Mean probability of transitioning to a smaller/less developed stage in the life cycle of the species, SSD-weighted 0.07 −0.77
Reproduction Φ Mean per-capita number of sexual recruits across stages in the life cycle of the species, SSD-weighted −0.83 0.30
 Mean sexual reproduction
 Degree of iteroparity S Spread of reproduction throughout the lifespan of the individual as quantified by Demetrius’ entropy (S). High/low S values correspond to iteroparous/semelparous populations −0.23 0.51
 Net reproductive rate Ro Mean number of recruits produced during the mean life expectancy of an individual in the population 0.04 0.75
 Mature life expectancy Lω Number of years from the mean age at sexual maturity (Lα) until the mean life expectancy (ηe) of an individual in the population 0.15 0.27
Explained variation, % 34.06 21.23
Cumulative percentage of explained variation 34.06 55.38

Loadings in bold indicate a high contribution (greater than ±0.50) of the life-history trait to the PCA axis.