Geographic Variation of the Screech Owls of the Deserts of Western North America

The Condor ◽  
1951 ◽  
Vol 53 (4) ◽  
pp. 161-177 ◽  
Author(s):  
Alden H. Miller ◽  
Loye Miller
Keyword(s):  
North America ◽  
Geographic Variation ◽  
Western North America

A morphometric study of geographic variation in the snowshoe hare (Lepus americanus)

1985 ◽  
Vol 63 (3) ◽  
pp. 567-579 ◽  
Author(s):  
David W. Nagorsen
Keyword(s):  
North America ◽  
Great Lakes ◽  
Geographic Variation ◽  
Principal Component ◽  
Lepus Americanus ◽  
Morphometric Study ◽  
Western North America ◽  
Environmental Selection ◽  
Local Selection ◽  
Central Canada

Geographic variation in Lepus americanus was studied by multivariate analyses of 15 cranial measurements. A total of 1494 specimens from the entire geographic range were grouped into 37 geographic samples of males and females. Principal component analyses demonstrated that hares are largest in eastern North America, Alaska, and northwestern Canada, and smallest in the Pacific Northwest. Size clines exist in the Appalachian Mountains and western North America but size is relatively uniform throughout central Canada and the Great Lakes. A multiple regression of size with 16 climatic variables factors demonstrated that size and climate are strongly correlated; the size trends may reflect environmental selection. The differentiation of hares from the western Cordillera and Pacific coast, the similarity of populations from central Canada and the Great Lakes, and the clines in the Appalachians and western North America were evident in discriminant analyses. These patterns of variation among populations can be attributed to both gene flow and local selection. There is no evidence from the morphometric analyses for classifying populations into the 15 subspecies currently recognized.

Geographic Variation in Fluted Projectile Points: A Hemispheric Perspective

1999 ◽  
Vol 64 (2) ◽  
pp. 215-230 ◽  
Author(s):  
Juliet E. Morrow ◽  
Toby A. Morrow
Keyword(s):  
North America ◽  
South America ◽  
Geographic Variation ◽  
Great Plains ◽  
North American ◽  
South American ◽  
Western North America ◽  
Radiocarbon Dates ◽  
Projectile Points ◽  
Fluted Points

This paper examines geographic variation in fluted point morphology across North and South America. Metric data on 449 North American points, 31 Central American points, and 61 South American points were entered into a database. Ratios calculated from these metric attributes are used to quantify aspects of point shape across the two continents. The results of this analysis indicate gradual, progressive changes in fluted point outline shape from the Great Plains of western North America into adjacent parts of North America as well as into Central and South America. The South American “Fishtail” form of fluted point is seen as the culmination of incremental changes in point shape that began well into North America. A geographically gradual decline in fluting frequency also is consistent with the stylistic evolution of the stemmed “Fishtail” points. Although few in number, the available radiocarbon dates do suggest that “Fishtail” fluted points in southern South America are younger than the earliest dates associated with Clovis points in western North America. All of these data converge on the conclusion that South American “Fishtail” points evolved from North American fluted points.

Male aggression and colour in divergent populations of the threespine stickleback: experiments with animations

1996 ◽  
Vol 74 (9) ◽  
pp. 1727-1733 ◽  
Author(s):  
Jeffrey S. McKinnon ◽  
J. D. McPhail
Keyword(s):  
North America ◽  
Geographic Variation ◽  
Gasterosteus Aculeatus ◽  
Threespine Stickleback ◽  
Agonistic Behaviour ◽  
Western North America ◽  
Colour Discrimination ◽  
Male Aggression ◽  
Nuptial Coloration ◽  
Negative Findings

We investigated the evolution of male agonistic behaviour and nuptial coloration in populations of the threespine stickleback, Gasterosteus aculeatus, with either monomorphic red or monomorphic black coloration. Specifically, we examined the responses of males from the two population types to computer-generated animations of males with black, red, or dull grey throats on otherwise identically coloured bodies. Males varied greatly in their aggressive responses among individuals and among trials, and did not show statistically significant discrimination towards the differently coloured animations. These results, therefore, do not suggest a role for interactions among males in the evolution of divergent male nuptial coloration. In addition, these negative findings are consistent with other studies of stickleback from western North America, suggesting that geographic variation in agonistic colour discrimination may account, in part, for the discrepancies between the results of earlier studies. Given the diverse methods of studies on this topic, however, methodological differences may also have contributed to the inconsistent results.

Geographic Variation in the Occurrence of Red- and White-Fleshed Chinook Salmon (Oncorhynchus tshawytscha) in Western North America

1989 ◽  
Vol 46 (7) ◽  
pp. 1107-1113 ◽  
Author(s):  
Jeffrey J. Hard ◽  
Alex C. Wertheimer ◽  
William F. Johnson
Keyword(s):  
British Columbia ◽  
North America ◽  
Geographic Variation ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Early Life History ◽  
Western North America ◽  
Flesh Color ◽  
Southeast Alaska ◽  
Southcentral Alaska

Flesh color, as reported by fishery processors, was surveyed in coded-wire tagged chinook salmon (Oncorhynchus tshawytscha) sampled from the 1983–85 Southeast Alaska commercial troll fisheries. Flesh color data were collected from 11 373 fish originating from 95 locations in western North America between southcentral Alaska and central California. White-fleshed chinook salmon were most common in stocks from coastal British Columbia, Southeast Alaska, and the tributaries of the Fraser River, British Columbia. Heterogeneity between neighboring locations was also greatest in this region, the most recently glaciated area of western North America. Differences in flesh color proportions are consistent with the hypothesis that chinook from the Pacific refuge colonized rivers in British Columbia and Southeast Alaska after the recession of the last Pleistocene glaciation. Genetic drift of populations founded by small numbers of parents is one explanation of the pattern of occurrence of white-fleshed chinook salmon. An alternate explanation is that geographic variation in the occurrence of red- and white-fleshed chinook salmon reflects evolutionary adaptations of these fish during early life history to local freshwater environments.

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