Individual soil mite data

Indiv 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.