Session Alignment

Three basic adaptive responses—regulatory , acclimatory , and developmental—may occur in organisms as they react to changing environmental conditions .

In all three , adjustment of biological features ( morphological adjustment ) or of their use ( functional adjustment ) may occur .

Regulatory responses involve rapid changes in the organism ’s use of its physiological apparatus—increasing or decreasing the rates of various processes , for example .

Acclimation involves morphological change—thickening of fur or red blood cell proliferation—which alters physiology itself .

Such structural changes require more time than regulatory response changes .

Regulatory and acclimatory responses are both reversible .

Developmental responses , however , are usually permanent and irreversible : they become fixed in the course of the individual ’s development in response to environmental conditions at the time the response occurs .

One such response occurs in many kinds of water bugs .

Most water - bug species inhabiting small lakes and ponds have two generations per year .