Data from: Multiple simultaneous treatments change plant response from adaptive parental effects to within-generation plasticity, in Arabidopsis thaliana

In general, studies on plant phenotypic plasticity concentrate on plant
responses to different levels of a single environmental factor. Under
natural conditions, however, multiple environmental factors often vary
simultaneously. I studied the consequences for lifetime fitness caused by
single treatments or treatment combinations by investigating patterns of
phenotypic plasticity within and between generations. The parental plants
(3 genotypes of the annual plant Arabidopsis thaliana) received zero, one
or two stress treatments at an early life-stage. The treatments included
wounding, shading, chilling, and their pairwise combinations. In the
second generation, offspring of treated plants received either the
parental or no treatment. Offspring of non-treated plants were reared
under all treatment conditions. Plants responded strongly to the
treatments, especially through delayed reproduction, which positively
affected lifetime fitness. Notably, treatment combinations triggered
stronger plastic responses on average. Because the delay in reproduction
was offset by a delay in senescence, the treatments resulted in a fitness
gain instead of a loss. However, under adverse environmental conditions,
this delay represents a potential fitness cost, especially when the time
for reproduction is limited. The treatments wounding and shading triggered
parental effects that increased fitness only in plants that themselves
received the treatment. Untreated offspring of wounded or shaded parents
performed like control plants. Also, these parental effects were not
accompanied by potential fitness costs, such as delayed reproduction.
Chilling triggered genotype-specific parental effects that increased or
reduced fitness. Of the treatment combinations only wounding and shading
resulted in genotype-specific parental effects that increased or reduced
fitness independently of offspring treatment. These results suggest that
the response of annual plants to treatment combinations triggers
predominantly within-generation plastic responses that include potential
fitness costs, which cannot be inferred from studies that manipulate
environmental factors individually. Therefore, single treatment studies
likely underestimate the costs of plasticity in natural environments.