W. Bradshaw et Cm. Holzapfel, GENETIC CONSTRAINTS TO LIFE-HISTORY EVOLUTION IN THE PITCHER-PLANT MOSQUITO, WYEOMYIA-SMITHII, Evolution, 50(3), 1996, pp. 1176-1181
Life-history theory relies heavily an the hypothesis that genetic trad
eoffs among the components of fitness constrain their independent evol
ution and joint maximization. Herein we show that selection on preadul
t development time in the pitcher-plant mosquito, Wyeomyia smithii,, l
eads to a correlated response in cohort mean generation time but no co
rrelated response in survivorship, fecundity. or cohort replacement ra
re. Lines selected for fast development achieve a higher capacity for
increase (r(c)) than lines selected for slow development, independentl
y of larval density. These results imply that tradeoffs due to underly
ing antagonistic pleiotropy affecting growth, development, survivorshi
p. and reproduction are not necessary constraints to life-history evol
ution. Previous work with W. smithii has shown a positive generic corr
elation between development time and a general, genetically coordinate
d diapause syndrome. We propose that the observed nontradeoffs among t
he components of r(c) may be subsumed into an even more fundamental tr
adeoff between performance during the summer generations and synchroni
zation of development and reproduction with the changing seasons, Cons
equently, critical tests of genetic tradeoffs as a constraint to the i
ndependent evolution or simultaneous optimization of fitness component
s may need to consider the seasonal context.