PARENT SESSION
Oral Session # 77: Plant Ecology VI: Temperature and Water Stress.
Presiding: C Ford
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Meeting Room 102.

Temperature and temperature variability in determining gradients in plant species range.

Thygerson, Tonya^*,1, Smith, Bruce¹, Hansen, Lee², Criddle, Richard², McCarlie, V.², ¹ BYU Dept Plant and Animal Science, Provo, UT² BYU Dept Chemistry and Biochemistry, Provo, UT

ABSTRACT- There are many factors that determine where a plant (an ectotherm) will grow. One of the primary factors is temperature. This paper develops the hypothesis that temperature (T) and temperature variability (T) are the primary climatic variables determining global-scale gradients in species range. The physiological factor defining adaptation of ectotherms to temperature is respiratory energy metabolism. Ectotherms adapt to the latitudinal/longitudinal gradients of T and T which correspond to their gradients of adapted energy metabolism. Natural selection results in ectotherms with metabolic properties corresponding with their environment. Measurements of the rates of respiration and energy production as a function of temperature show that respiratory rates and efficiency of ectotherms are closely adapted to their native environment. Principles developed in this paper yield fundamental laws of ecology that allow the calculation of the contributions of global temperature patterns to the formation of the global gradient of species range. Relative values of range can therefore be calculated from data on abiotic variables. Predictions agree with known patterns of plant distribution.

Key words: plant distribution, Temperature, respiratory metabolism