Morphological canalization, integration and plasticity in response to
population density in Abutilon theophrasti: influences of soil
conditions and growth stages
Abstract
Phenotypic integration and developmental canalization have been
hypothesized to constrain the degree of phenotypic plasticity, but there
is little evidence for the relationships among the three processes in
different environments, especially for plants under natural conditions.
To address this issue, we conducted a field experiment by subjecting
plants of Abutilon theophrasti to low, medium and high densities, under
infertile and fertile soil conditions, measured a variety of traits and
analyzed canalization (coefficient of variation [CV]), integration
(coefficient of integration [CI] and the number of significant
correlations of a trait with other traits [NC]), and plasticity (REL
RDPIs and ABS RDPIs) in these traits and their relationships at two
stages of plant growth. Our results showed an increase in mean CV, NC
and ABS RDPIs of traits with density, and the positive correlations
between trait NC and ABS RDPIs became stronger with higher densities but
weaker over time in fertile soil, while correlations among trait CV, NC
and ABS RDPIs became stronger over time in infertile soil. Results
suggested shared or cooperation mechanisms among phenotypic integration,
canalization and plasticity. Soil conditions and growth stage may affect
responses of these correlations to density via modifying plant size and
competition strength. The attenuated canalization and enhanced
integration may be helpful for the production of plasticity, especially
under intense competition.