Biology Reference
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but is selected to die in a particular generation, it will participate in the
reproductive matings selection process for that generation producing any
resultant offspring, and then die.
Mortality rate for a cohort of a given generation age can be set from
<functionpoint x=“0” y=“0”/>
where there is no mortality (probability y = 0) for generation x = 0, to
<functionpoint x=“0” y=“1”/>
which specifi es that there is 100% mortality (y = 1) for individuals of a cohort
aged generation 0. The latter case would describe monocarpic (semelparous)
annual species, for which all individuals of each newly generated cohort
(age x = 0) would reproduce according to input specifi cations and then
all individuals of that cohort would die. The only remaining individuals
would be the newly generated cohort, which would then also die after
reproducing, and so on. Since the individuals of the reproducing generation
cohort die, they are removed from the data set and the grid points they
occupied become available for establishment by the next cohort. For an
annual monocarpic semelparous species, the NEWGARDEN data output
will be the same for the cohorts and each age of the entire population since
there are no surviving mature individuals beyond a given cohort. Only the
created new offspring cohort goes on to the next age and reproduces, and
then members of that cohort die.
Statements for a biennial with no mortality in the fi rst year would be
(x = age; y = probability of death):
<functionpoint x=“0” y=“0”/>
<functionpoint x=“1” y=“1”/>
For a triennial with 35% mortality in year 1, and 43% mortality of remaining
cohort survivors in year 2, they would be:
<functionpoint x=“0” y=“0.35”/>
<functionpoint x=“1” y=“0.43”/>
<functionpoint x=“2” y=“1”/>
As is true for a triennial, there is 100% mortality for remaining individuals of
a cohort in its third generation. Note that mortality “compounds” through
the years, so that 43% of the 65% of the original individuals of year 1 die at
reproductive bout 2 (age x = 1). Only 37.1% of the initial year 1 individuals
survive to reproduce at the end of year 2. Thus, the mortality rate designated
for a cohort of given age applies only to those individuals of that cohort still
living, not to a percentage of the number in the initial cohort.
For each cohort, NEWGARDEN selects and deletes the specified
percentage of remaining individuals, as designated for a given cohort age,
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