In many cases, rapid counteradaptation
by parasites can occur because of their relatively short generation times and high population densities, and a variety of adaptations may assist this.
by some lineage of insects enables them to exploit these plants and thus undergo their own adaptive radiation in the absence of competition form other insects.
A striking characteristic of this counteradaptation
is its cyclic behavior on an annual basis: lowest frequency in May, increasing frequency through August, and a drop in frequency (to just above that of the previous May) by the following May for populations in or near cotton fields (Luttrell et al.
High alkalinity of the midguts of many lepidopteran larvae has been suggested to be a counteradaptation
to plant tannins, because many tannin-protein complexes may dissolve under alkaline conditions (Berenbaum 1980).
Active pollination, and associated morphological and behavioral traits, can be selected for in a pollinator population when a small number of co-pollinators are present and the behavior does not require any counteradaptation
on the part of the plant (Pellmyr and Huth 1994, Pellmyr et al.