EVOLUTIONARY IMPLICATIONS OF WING AND SIZE VARIATION IN RED-WINGED BLACKBIRD IN RELATION TO GEOGRAPHIC AND CLIMATIC FACTORS - A MULTIPLE REGRESSION ANALYSIS

Power, Dennis M. (Royal Ontario Museum and University of Toronto, Toronto 5, Ont. Can.) 1969. Evolutionary implications of wing and size variation in the red-winged blackbird in relation to geographic and climatic factors: a multiple regression analysis. Syst. Zool, 18:363-373.—In red-winged blackbirds from central North America, geographic variation in wing length is a good indicator of geographic variation in body size. Multiple regression analysis is used to consider the relationship between geographic variation and eight geographic and climatic factors. Variation in males appears inversely related to two factors, latitude and July wet-bulb temperature, while variation in females is inversely related to only wet-bulb temperature. The statistical associations may indicate natural selection in terms of thermoregulatory efficiency. [Geographic variation. Thermoregulation. Multiple regression. Agelaius.]. © 1969, Oxford University Press. All rights reserved.