 | Shefferson, R.P. and D.A. Roach. 2010. Longitudinal analysis of Plantago: | |
| adaptive benefits of iteroparity in a short-lived, herbaceous perennial. Ecology 91:441-447. |
Abstract Theory suggests that iteroparity may confer greater fitness than semelparity
in situations in which temporal environmental variation is high and unpredictable.
Variable age-specific mortality, density dependence, and other factors may also favor
iteroparity over semelparity. Here, we empirically test the adaptive benefits of greater
numbers of reproductive years in a study of reproductive schedules in an
experimental population of a short-lived polycarpic perennial, Plantago lanceolata. A
large experimental population was established that included four cohorts with similar
genetic structure. Individuals were censused for mortality, size, and reproduction for
seven years. Plants experienced variable numbers of reproductive years, but one or
two years were most common (;46.7% of the population reproduced only once). The
probability of flowering at least once prior to death was determined strongly by
extrinsic, environmental or intrinsic but environmentally influenced variables, including
early-life size, cohort, and block, but also varied with a number of interactions involving
paternal lineage. Maternal effects explained small but significant components of the
variance in the number of reproductive years among individuals in each cohort, while
paternal effects were significant in only two cohorts. Number of reproductive years
contributed significantly to fitness in this system, more so than all other variables
tested, although most of the variation in relative fitness may be attributed ultimately to
environmental influences. We suggest that the high proportion of each cohort
composed of plants reproducing only once may be due to environmental constraints
on either growth or size. Such environmental influences, particularly on early life size,
may result in small but important indirect effects on fitness.
Copyright 2010 Richard P. Shefferson. All rights reserved.
Shefferson and Roach 2010
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |