2.1.1. Variation within species
Populations respond to spatial and temporal variation
in the environment by selection and adaptation.
Hence, the most important aspect of genetic variation
is the buffering it provides against fluctuations in environmental
conditions (Hattemer, 1994). Adaptation
involves physiological and evolutionary aspects (Larsen,
1988): the individual reacts to a perturbation
through physiological adaptation, which is limited by
the homeostatic capacity of its genotype. If not all genotypes
in a population are physiologically able to buffer
the perturbation, selectionp rocessesw ill induce adaptation
at the population level (Hattemer and Ziehe,
1987; Hattemer and Mtiller-Starck, 1989). The adapt