MODELING AND ANALYZING DENSITY-DEPENDENT POPULATION PROCESSES - COMPARISON BETWEEN WILD AND LABORATORY STRAINS OF THE BEAN WEEVIL, CALLOSOBRUCHUS-CHINENSIS (L)
E. Kuno et al., MODELING AND ANALYZING DENSITY-DEPENDENT POPULATION PROCESSES - COMPARISON BETWEEN WILD AND LABORATORY STRAINS OF THE BEAN WEEVIL, CALLOSOBRUCHUS-CHINENSIS (L), Researches on population ecology, 37(2), 1995, pp. 165-176
Three models were constructed for analyzing the population characteris
tics of C. chinensis on stored beans; model A describing the whole rep
roductive process with a single equation, model B describing the three
age-specific processes (oviposition, egg survival and larval survival
) with separate equations, and model C which describes all these proce
sses not for the whole habitat but for the individual beans comprizing
it. The logit equation was employed here as a common basis to describ
e the density-response relationship involved. All three models showed
very good fit to the experimental data obtained for both laboratory an
d wild strains of the weevil. The parameter values characterizing the
population dynamics were, however, widely different between the two st
rains; the laboratory one which had been reared for some 500 generatio
ns showed significantly higher reproductive capacity, less sensitive a
nd gentler response to crowding in both adult and egg stages, and more
uniform egg distribution among individual beans, as compared with the
wild strain newly introduced. Sensitivity analyses using these models
suggested that these changes in population characteristics have been
attained by the process of domestication or adaptation to stable labor
atory conditions through a long period of time. This process seemed in
effect to have optimized the population's performances in the laborat
ory environment. Evolutionary significance of such optimization was di
scussed with reference to the selection pressure which may have acted
upon individuals.