Simulating biases in the timing of collection within
flowering periods of individuals
In addition to biases towards collection of early or late individuals
within a local population, botanists may also preferentially collect
individuals from the early or late portion of their individual flowering
period (i.e., individual collection bias). In some cases, collectors may
preferentially collect individuals that are proximate to their peak
flowering date because this is when the most flowers are displayed. In
other cases, collectors may preferentially collect specimens that have
only recently begun to flower, when floral structures may exhibit less
damage from inclement weather or herbivores, or proximate to flowering
termination in cases where the collector prefers specimens that include
both flowers and fruits. Accordingly, for each population of each
species, we simulated DOYs within each individual’s flowering period
both at random (i.e., without bias) and with three different types of
bias (Fig. S2). Unbiased collections were simulated by selecting a
random date chosen uniformly within the flowering period of each sampled
individual (Fig. S2a). To represent a bias toward collection of
individuals close to their peak (median) flowering DOY, we sampled
collection dates from a truncated normal distribution centered on an
individual’s mean flowering date and with σ = 25% of the flowering
duration for that species and location (henceforth referred to asmean-biased collection data , Fig. S2b). To represent a bias
toward collection dates shortly after flowering onset (henceforth,onset-biased collection data ), we sampled collection dates from a
truncated normal distribution centered on a date 25% earlier than the
mean flowering onset date of that individual (σ = 25%; Fig. S2c).
Finally, to represent a bias toward collection on dates shortly before
flowering termination (henceforth termination-biased collection
data ), we sampled collection dates from a truncated normal distribution
centered on a date 25% later than the mean flowering onset date of that
individual (σ = 25%; Fig. S2d). As with examinations of
population-level bias, collection biases within the flowering periods of
individuals were examined only for the subset of species for which
phenological responsiveness to mean annual temperature equaled 4
days/˚C, intrapopulation variation was high (σ = 30), individual
flowering duration was moderate (30 days), and no population-level bias
was present.