A 1968 study conducted by Rosenzweig et al. found an extremely strong direct relationship between wolf pack size and this variable. Thorson's rule states this variable is inversely related to number of eggs for benthic marine invertebrates. Ranges in this variable for an organism increase as this variable increases according to Rapoport's rule. Hesse's rule directly correlates heart size to this variable, in an extension 
A 1968 study conducted by Rosenzweig et al. found an extremely strong direct relationship between wolf pack size and this variable. Thorson's rule states this variable is inversely related to number of eggs for benthic marine invertebrates. Ranges in this variable for an organism increase as this variable increases according to Rapoport's rule. Hesse's rule directly correlates heart size to this variable, in an extension of Bergman's rule, stating that this variable is directly related to organism size. The best-known gradient in (*) biodiversity occurs in relation to this other variable. Elevation, humidity, and this climate factor are the most important factors determining the distribution of biomes. During winter, birds migrate to areas that have a lower value for this coordinate. For 10 points, name this geographical coordinate that is 90 degrees for polar organisms and 0 degrees if they live near the equator
A 1968 study conducted by Rosenzweig et al. found an extremely strong direct relationship between wolf pack size and this variable.