TY - JOUR
T1 - Optimal reproductive effort in stochastic, density-dependent environments
AU - Benton, T. G.
AU - Grant, Alastair
PY - 1999/6/1
Y1 - 1999/6/1
N2 - The amount of effort organisms should put into reproducing at any given time has been a matter of debate for many years. Early models suggested a simple rule of thumb: iteroparity should be favored when juvenile survival is relatively variable and semelparity when adult survival is relatively variable. When more mathematically complex models were developed, these simple conclusions were found to be special cases. Variability can select toward iteroparity or semelparity depending on a number of factors irrespective of relative adult/juvenile survival (e.g., the density-independent models of Orzack and Tuljapurkar). Using new techniques, we estimate the ESS reproductive effort for stage-structured models in density-dependent and stochastic conditions. We find that variability causes significant changes in reproductive effort, these changes are often small (± 10% of determinstic ESS effort, but up to 50% change in some instances), and the amount that effort increases or decreases depends on many factors (e.g., the deterministic population dynamics, the vital rates affected by density, the amount of variation, the correlations between the vital rates, the distribution from which the variation is drawn, and the deterministic ESS effort). In a variable environment, semelparity is the ESS in only 3.5% of cases; iteroparity is the rule.
AB - The amount of effort organisms should put into reproducing at any given time has been a matter of debate for many years. Early models suggested a simple rule of thumb: iteroparity should be favored when juvenile survival is relatively variable and semelparity when adult survival is relatively variable. When more mathematically complex models were developed, these simple conclusions were found to be special cases. Variability can select toward iteroparity or semelparity depending on a number of factors irrespective of relative adult/juvenile survival (e.g., the density-independent models of Orzack and Tuljapurkar). Using new techniques, we estimate the ESS reproductive effort for stage-structured models in density-dependent and stochastic conditions. We find that variability causes significant changes in reproductive effort, these changes are often small (± 10% of determinstic ESS effort, but up to 50% change in some instances), and the amount that effort increases or decreases depends on many factors (e.g., the deterministic population dynamics, the vital rates affected by density, the amount of variation, the correlations between the vital rates, the distribution from which the variation is drawn, and the deterministic ESS effort). In a variable environment, semelparity is the ESS in only 3.5% of cases; iteroparity is the rule.
KW - Density-dependence
KW - Iteroparity
KW - Reproductive effort
KW - Semelparity
KW - Stochastic environments
UR - http://www.scopus.com/inward/record.url?scp=0032781303&partnerID=8YFLogxK
U2 - 10.1111/j.1558-5646.1999.tb05363.x
DO - 10.1111/j.1558-5646.1999.tb05363.x
M3 - Article
AN - SCOPUS:0032781303
VL - 53
SP - 677
EP - 688
JO - Evolution
JF - Evolution
SN - 0014-3820
IS - 3
ER -