Data from: Pace and shape of senescence in three species of duckweed

Senescence is progressive bodily deterioration associated with declines in
survival and fecundity in older age classes. There is great diversity in
patterns of senescence across species, but these patterns can be difficult
to compare formally due to variation in the absolute time scales in which
species live and die: members of some species live for a matter of days,
others for millennia. To address this issue, the ‘pace-shape’ approach was
developed to decouple absolute time from analyses and instead standardize
life history traits in terms of average life expectancy, facilitating
intra- and interspecific comparisons. Here, we use this approach to
distinguish the generic form of demographic trajectories (shape) from the
time scale on which the trajectories occurred (pace) in three species of
tiny, free-floating aquatic plants known as duckweeds (Lemna gibba L., L.
minor L., and L. turionifera Landolt), which have mean lifespans of less
than a month under typical lab conditions, and exhibit age-related
declines in survivorship and reproduction. Using a randomized block design
in which we tracked a final total of 430 individuals, we report
differences in pace and shape among the three species. Specifically, the
largest, least-fecund, and typically longest-lived species, L. gibba,
tended to exhibit more rapid decreases in time-standardized survivorship
and fecundity compared to the other two species. This study emphasizes
variation in aging patterns that can be found among plant species,
including those in the same genus, and provides further validation for the
utility of applying the pace and shape approach in interspecific
comparisons.