Life history traits of Potamopyrgus antipodarum in variable salinity and temperature

Organisms exposed to major environmental change face atypical and
stressful conditions across multiple environmental variables, yet studies
of phenotypically plastic responses historically focus on one
environmental variable at a time. Evaluating multivariate plasticity of
traits across different, simultaneously varying environmental variables
provides new insights into the fate of populations amidst environmental
changes. We aimed to investigate plasticity in multivariate environments
by 1) examining the individual and joint effects of two environmental
variables and 2) calculating genotype-by-environment interactions and
genetic correlations of character states to investigate potential
evolutionary constraints. We performed a lab controlled-environment
experiment under a full factorial design of low and high temperatures and
salinities with multiple maternal lineages of a parthenogenetic freshwater
snail, Potamopyrgus antipodarum. Our results revealed that predictions of
plastic trait responses among multivariate environments may be unexpected
due to non-additive effects of environmental variables and varying
magnitudes and orientations of genetic correlations among fitness-related
traits. Considering multivariate environments provides deeper insight and
advancement of understanding trait evolution by revealing trait patterns
that would otherwise be missed in univariate studies.