Areography of North American fishes, amphibians, and reptiles. American Museum novitates ; no. 2802

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New York, N.Y. : American Museum of Natural History
"Sizes of geographic ranges of species of freshwater fishes (635), amphibians (141), and reptiles (199) occurring north of Mexico in North America were measured and compared with each other and with ranges of birds and mammals. All groups have 'hollow curve' frequency distributions in which most species have small ranges; and all groups have latitudinal gradients in which more species occur at lower latitudes. For fishes and amphibians the greatest density is in the southeastern United States and not the southwest. The frequency distributions of range sizes for amphibians and reptiles are approximately lognormal. The geometric means (in 10[superscript 5] km[superscript 2] units) for ranges of species in these groups are: fishes 0.82, salamanders (Caudata) 0.86, lizards (Lacertilia) 2.8, turtles (Chelonia) 4.1, frogs and toads (Anura) 4.6, snakes (Serpentes) 6.2, and the alligator (Crocodilia) 8. Comparable means for mammals and birds are 5.8 and 16, respectively. At most local areas in North America, the percentage of the continental fauna present for each of these groups is correlated with the mean size of the geographic ranges in the groups. Exceptions for certain localities or subgroups are of interest. Species of amphibians and reptiles occurring in places of higher diversity have smaller geographic ranges. Available space (probably chiefly related to climatic conditions) and analytical artifacts provide a better explanation than competition for this correlation. Fishes were not examined in this regard; adequate data have not been assembled. Amphibians and reptiles have a higher percentage of species that are North American endemics than do mammals and birds, which are groups with generally larger species ranges. On the average, fishes have smaller ranges than amphibians and reptiles but have a higher percentage of intercontinental cosmopolitan species (or a smaller percentage of North American endemics) than do amphibians and reptiles. This is because fishes have Arctic and coastal proclivities not present in the other groups"--P. [1].
16 p. : ill., maps ; 26 cm.
Includes bibliographical references (p. 15-16).