. CUMULATIVE PERCENTAGE COMPOSITION Fig. 131. Cumulative percentage composition of mammalian component of Coloradan life-zones attribut- able to each areographic faunal element. Chihuahuan species drop out, and highland kinds, especially those of the Boreo-cordil- leran element, evince a concomitant in- crease in importance. The coniferous forest "closes up" at the interface between Transi- tion and Canadian life-zones. The Canadian and Hudsonian zones differ in the general ab- sence of the Autochthonous Coloradan ele- ment in the higher zone and the propor- tionally greater importan
. CUMULATIVE PERCENTAGE COMPOSITION Fig. 131. Cumulative percentage composition of mammalian component of Coloradan life-zones attribut- able to each areographic faunal element. Chihuahuan species drop out, and highland kinds, especially those of the Boreo-cordil- leran element, evince a concomitant in- crease in importance. The coniferous forest "closes up" at the interface between Transi- tion and Canadian life-zones. The Canadian and Hudsonian zones differ in the general ab- sence of the Autochthonous Coloradan ele- ment in the higher zone and the propor- tionally greater importance of Cordilleran species there. As regards actual species com- position, the Cordilleran fauna of the two zones is the same. Some Boreo-cordilleran species typically are absent from the Hud- sonian Zone, however. The Alpine Zone compares closely with the Hudsonian in species composition, a fact consistent with the observation made earlier TABLE 32 Percentage of species of each areographic faunal element prevalent in a given Coloradan life-zone. Life-zone (and number of species) Cordil- leran Boreo- cordil- leran Neo- Cam- Great Eastern tropical pestrian Basin Yuman Chihua- huan Autoch- thonous Wide- Coloradan spread 100. 100. 100. Upper Sonoran (97) Transition (63) Canadian (53) Hudsonian (39) Alpine (17) 100. 100. 100. 100. 100.
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectmammals
