Temperature tolerance of the mosquitofish, <i>Gambmia affinis</i> (Baird and Girard)

Abstract

The capacity of a warm‐adapted population of mosquito fish ( Gambusia affinis ) from the Sonoran Desert and a cold‐adapted population from northern Utah to adjust to changing environmental temperatures has been described in terms of four criteria: (1) critical thermal maxima, (2) resistance times at high, lethal temperatures, (3) upper incipient lethal temperatures, and (4) lower lethal temperatures. Non‐genetic scope for adaptation as related to changes in the thermal history of the individual and expressed in terms of the tolerance domain was identical for both populations. Genetic differences in adaptive capacity were apparent. The cold‐adapted population was less tolerant of heat and more tolerant of cold as would be anticipated.