ADAPTATION OF HEART AND LUNG WEIGHT TO HIGH ALTITUDE IN THE ROBIN By
نویسنده
چکیده
Adaptation of heart and lung weight to high altitudes has not been conclusively studied in bird populations of one species. Rensch (1931) concluded that the ratio of heart weight to body weight increases with altitude in certain tropical passerines. Moreau (1944), while agreeing that such a trend would be expected, maintained that Rensch’s data were unsatisfactory. Altitudinal differences in the ratio of heart weight to body weight claimed by Strohl (1910) for ptarmigan have since been shown to be interspecific differences (Johnston, 1963). Hartman (1954, 19.55), Norris and Williamson (19.55) and Williamson and Norris (1958) have presented data on relative heart size in high and low altitude bird populations. Only Norris and Williamson (op. cit.) have attempted to show that adaptation in heart weight to high altitude occurs within different populations of the same species. Their data suggest but do not prove that relative heart weight varies directly with altitude. The present study was undertaken to provide a rigorous analysis of variation in weight of the heart and lungs in subspecifically distinct populations of American Robins (Turdus migratorius) from montane and lowland situations.
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