DOI: 10.5061/dryad.x3ffbg7qh
title: Novel environments induce variability in fitness-related traits

description: Environmental change from anthropogenic activities threatens individual
 organisms, the persistence of populations, and entire species. Rapid
 environmental change puts organisms in a double bind, they are forced to
 contend with novel environmental conditions but with little time to
 respond. Phenotypic plasticity can act quickly to promote establishment
 and persistence of individuals and populations in novel or altered
 environments. In typical environmental conditions, fitness-related traits
 can be buffered, reducing phenotypic variation in expression of traits,
 and allowing underlying genetic variation to accumulate without selection.
 In stressful conditions, buffering mechanisms can break down, exposing
 underlying phenotypic variation and permitting the expression of
 phenotypes that may allow populations to persist in the face of altered or
 otherwise novel environments. Using reciprocal transplant experiments of
 freshwater snails, we demonstrate that novel conditions induce higher
 variability in growth rates and, to a lesser degree, morphology (area of
 the shell opening) relative to natal conditions. Our findings suggest a
 potentially important role of phenotypic plasticity in population
 persistence as organisms face a rapidly changing, human-altered world.
description: File 1: site information At three time
 intervals during the experiment at least two days apart, we measured
 temperature, conductivity, flow rate, and dissolved oxygen with a sonde
 (Yellow Springs Instrument, model 85) adjacent to the containers
 containing the experimental snails. Midway through the experiment, we
 measured pH (Corning pH meter, Model 430), magnesium and calcium carbonate
 hardness (Hach Test Kit, Model 5-EP), and ammonia (Hach Test Kit, Model
 NI-8) from water samples adjacent to the platforms. To analyze food
 quality and quantity, we collected epiphyton samples at each site by
 scrubbing an equivalent surface area of submerged macrophytes from the
 same locations where we collected macrophytes to feed the
 snails. File 2: snail_measurements
 Before and after each pair of experimental trials, we measured
 specific growth rate. We estimated specific growth rate by measuring shell
 length with an ocular micrometer (Leica S6E). To obtain consistent
 measurements, we used the same orientation and angle for all snails with
 the aperture facing upwards and the shell slightly rotated to measure
 maximum shell length.  File 3:
 Physella_morphology Before and after each pair of
 experimental trials, we measured three defense-related traits that are
 commonly induced by crayfish and can protect snails from predation by
 crayfish (Crowl and Covich, 1990; Dewitt et al., 2000; Stevison et al.,
 2016): specific growth rate, aperture shape and aperture area.  To obtain
 consistent measurements, we used the same orientation and angle for all
 snails with the aperture facing upwards and the shell slightly rotated to
 measure maximum shell length. We used an image-processing microscope
 (Olympus SZX2-ILLT) and ImageJ software (Schneider et al., 2012) to
 analyze shell morphology for each snail.