Affiliations: Department of Geography,Nanjing Normal
University,Nanjing 210097,China, E-mail:[email protected] | Department of Biology,the University of New
Mexico,Albuquerque,NM 87131-1091,USA
Abstract: Two revised drafts about a simple evolution trade-off function
studied by Mitchell( Mitchell,2000) were put up first.Considering the complex
of the environment,or the nonlinear interaction of the environment and
species,we put up two new cost functions:c ( u,z) = c_0 + c_1 u +
k(z+az²)/u, u >0; c (u,z)= c_0 + c_1u + kz^d/u, u>0. d>0. In the first case,if the environment is adverse to species ( a
>0),the region of low-stress which is more suitable for the intolerant
species is very small,and at the same environment stress z,the tolerant species
will pay the more cost than it will paid in the normal environment.However the
tolerant species will pay more cost but low strategies in the environment of a
< 0 than that it will paid in the environment of a =0 or a>0.In the
second case,the results showed that the greater the stress of the environment
is,or the more complex the environment is,the lower cost the intolerant species
will pay in the region of z < 1.In order to exist or to evolve from an
environment of high-stress,the organisms must possess a higher u,or a better
means of mitigating of the stress of environment.Meanwhile in the region d >
1,when d decrease,the intolerant species will pays more lower cost of
exploiting a habitat in the low-stress environment while the tolerant one will
pays more lower cost in the high-stress environment.This means that scale d
describes the selection character of the species system in the evolution
process,the smaller the d( d < 1 ) is,the better the selection or the
mitigation the system will possesses.
