SINGLE-SPECIES DYNAMICS IN CHANGING ENVIRONMENTS

A priori bounds are obtained for positive solutions of scalar delay di fferential equations of the form dN(t)/dt=N(t)f(t,N(t-tau(t)) modellin g single species dynamics in a temporally changing environment. Suffic ient conditions are derived for the existence of periodic and almost p eriodic solutions when f is a periodic and almost periodic function re spectively in t. Applications of our analysis enable the derivation of known results in Gopalsamy et al. (1994), Gopalsamy and Ladas (1990), Ladas and Qian (1993) and Lalli and Zhang (1994) as special cases.