DOI: 10.5061/dryad.pq161
title: Data from: How well can body size represent effects of the environment on demographic rates? Disentangling correlated explanatory variables

description: Demographic rates are shaped by the interaction of past and current
 environments that individuals in a population experience. Past
 environments shape individual states via selection and plasticity, and
 fitness-related traits (e.g. individual size) are commonly used in
 demographic analyses to represent the effect of past environments on
 demographic rates. We quantified how well the size of individuals captures
 the effects of a population's past and current environments on
 demographic rates in a well-studied experimental system of soil mites. We
 decomposed these interrelated sources of variation with a novel method of
 multiple regression that is useful for understanding nonlinear
 relationships between responses and multicollinear explanatory variables.
 We graphically present the results using area-proportional Venn diagrams.
 Our novel method was developed by combining existing methods and expanding
 upon them. We showed that the strength of size as a proxy for the past
 environment varied widely among vital rates. For instance, in this
 organism with an income breeding life history, the environment had more
 effect on reproduction than individual size, but with substantial overlap
 indicating that size encompassed some of the effects of the past
 environment on fecundity. This demonstrates that the strength of size as a
 proxy for the past environment can vary widely among life-history
 processes within a species, and this variation should be taken into
 consideration in trait-based demographic or individual-based approaches
 that focus on phenotypic traits as state variables. Furthermore, the
 strength of a proxy will depend on what state variable(s) and what
 demographic rate is being examined; that is, different measures of body
 size (e.g. length, volume, mass, fat stores) will be better or worse
 proxies for various life-history processes.
description: Individual soil mite
 dataIndiv is a data frame
 stored in "Individual soil mite data.Rdata" which contains the
 following columns relevant to the sampling experiment. *trt* has levels
 that represent the food treatment: T1 (constant), T2 (famine), T3
 (declining), T4 (fluctuating) *pop.ID* is a unique identifier for each of
 2 replicate populations per treatment. *date* is the date when a sampling
 event began *stage* is the life stage of the individual at the beginning
 of the 24 hour sampling period. *ind.ID* is a unique identifier of an
 individual observed for a sampling period. *s24* is 1 if the individual
 was alive after 24 hours, 0 if it was dead, or NA if it was lost. *t24*
 indicates transiton to either the same stage as the beginning of the
 sampling period (initial stage) the next, or in between stages
 (quiescent). *f24* is the number of eggs laid in the 24 hour sampling
 period. *l0* is the body length at the beginning of the sampling period
 (mm). *l24* is the body length at the end of the sampling period (mm).
 *density* is the approximate value of body lenghths summed over the
 population on the date of sampling (see apendix S2 from publication) (mm).
 *supply* is food given divided by density on the date of sampling (mg/mm).
 *food* is the amount of food given to the population on that date (mg).
 *density.s* is the density scaled to have mean 0 and variance 1.
 *supply.s* is the supply scaled to have mean 0 and variance 1. *l0.s* is
 body length scaled to have mean 0 and variance 1. *day* is the number of
 days since the start of the experiment.Egg size from
 samplingeggdat is a data frame
 stored in "Egg size from sampling.Rdata" contianing measurments
 of individual eggs from sampled females. *egg.ID* is a unique identifier
 for an egg. *pop.ID*, *date*, *trt*, *s24*, *f24*, *l0*, *l0.s*,
 *density*, *density.s*, *supply*, and *supply.s* are the same as in the
 individual data in another file. *fem.ID* is the same as indiv.ID above
 for the mother of the eggs. *esize* is the size of the sampled egg
 (mm).Population Counts with
 PredictorsPop.counts is a data
 frame stored in "Population Counts with Predictors.Rdata"
 containing stage specific counts from both sampling and counting
 populations. *date*, *trt*, *pop.ID*, *density*, *supply*, *food*,
 *density.s*, *supply.s*, and *day* are the same as in the individual data
 in another file. *pop.type* is the type of the population counting or
 sampling (see appendix S1 for details). *eggtot*, *larvaetot*, *prottot*,
 and *trittot* are are *4 times* the number of soil mites in a given stage
 (egg, larvae, protonymph, tritoonymph) counted in a quarter of the tube
 where the population was living (see appendix S1 for details). *maletot*
 and *femaletot* are the number of adult mites counted in the entire
 population (see appendix S1 for details).