Fever is increasingly viewed as an adapted facultative response (Kluger et al. 1996).
Acclimation, in turn, is defined as a facultative response to changes in a single environmental variable, typically in the adult stage [1], [22].
This is a natural facultative response in female rodents when suckling.
It is difficult, however, to distinguish passive inherent response to chimeric development from active facultative response during social conflicts.
Furthermore, they suggested use of the estuary is a facultative response to growing conditions, and found similar relationships between population abundance and individual body sizes.
Many of these of disturbances can be considered unpredictable labile, or transient, perturbation factors that cause a facultative response at the individual level (e.g., Rykiel 1985; Wingfield 2003).
Populations of E. tynerensis characteristically exhibit a single life-history mode, suggesting that local habitat parameters are highly influential, via either selection for a facultative response or for particular genotypes [ 37].
However, evidence is growing, in many taxa, that as the adversity (harshness) and uncertainty of the environment increase cooperation is enhanced and we present a model here that attempts to explain this phenomenon as an adaptive facultative response favoured by selection.
