scholarly journals Geographic variation in thermal physiological performance of the intertidal crab Petrolisthes violaceus along a latitudinal gradient

2014 ◽  
Vol 217 (24) ◽  
pp. 4379-4386 ◽  
Author(s):  
J. D. Gaitan-Espitia ◽  
L. D. Bacigalupe ◽  
T. Opitz ◽  
N. A. Lagos ◽  
T. Timmermann ◽  
...  
Keyword(s):  
Geographic Variation ◽  
Latitudinal Gradient ◽  
Physiological Performance ◽  
Intertidal Crab

Geographic Variation in Clutch Size in the Northern Flicker (Colaptes auratus): Support for Ashmole's Hypothesis

The Auk ◽  
1984 ◽  
Vol 101 (4) ◽  
pp. 698-706 ◽  
Author(s):  
Walter D. Koenig
Keyword(s):  
Geographic Variation ◽  
Clutch Size ◽  
Latitudinal Gradient ◽  
Size Variation ◽  
Inverse Correlation ◽  
Climatic Conditions ◽  
Substantial Portion ◽  
Seasonal Fluctuations ◽  
Northern Flicker ◽  
Colaptes Auratus

Abstract The Northern Flicker (Colaptes auratus), a common hole-nesting North American woodpecker, exhibits a highly significant latitudinal increase in clutch size. Using preserved clutches and information on climatic conditions and breeding densities of confamilial species, I examined the hypothesis that this geographic trend is the result of seasonal fluctuations in resources ("Ashmole's hypothesis"; Ashmole 1961, 1963; Ricklefs 1980). Clutch size is significantly correlated both with the ratio of summer productivity to estimated breeding densities of all woodpecker species and with the ratio of summer to winter productivity, supporting Ashmole's hypothesis. In addition, a substantial portion of the latitudinal gradient can be directly explained by the seasonality of resources, primarily because of an inverse correlation between clutch size and winter productivity. These results provide the first corroboration of Ashmole's hypothesis from an examination of intraspecific clutch-size variation and suggest that geographic trends in fecundity in some cases may be largely attributable to trends in seasonal fluctuations of resources.

Geographic variation in balsam fir: 11-year results in the Lake States

1976 ◽  
Vol 6 (3) ◽  
pp. 389-394 ◽  
Author(s):  
D. T. Lester ◽  
C. A. Mohn ◽  
J. W. Wright
Keyword(s):  
Geographic Variation ◽  
Latitudinal Gradient ◽  
Shoot Elongation ◽  
Balsam Fir ◽  
Geographic Pattern ◽  
Spring Frost ◽  
Lake States ◽  
Phenotypic Instability ◽  
Seed Provenance

Up to 60 balsam fir provenances were evaluated at five locations in the Lake States at an age of 11 years from seed. Provenance effects were statistically significant at each location and, in general, eastern provenances were taller and produced more branches than western ones, while the initiation of shoot elongation followed a latitudinal gradient, with earliest flushing among provenances from north of 49° N. There were large differences, however, between some provenances from the same state or province. Provenance-plantation interaction was present in all tested combinations of plantations, but no geographic pattern of phenotypic instability was found. The observed results may reflect a geographic pattern of high vigor in eastern provenances confounded by effects of spring frost mediated through phenology of shoot elongation. Certain provenances have the desirable combination of vigor and late flushing.

Cognitive and physiological performance of soldiers while they carry loads over various Terrains

1999 ◽  
Author(s):  
Harrison P. Crowell ◽  
Andrea S. Krausman ◽  
William H. Harper ◽  
Jim A. Faughn ◽  
Marilyn A. Sharp ◽  
...  
Keyword(s):  
Physiological Performance

To Whistle or Not to Whistle? Geographic Variation in the Whistling Behavior of Small Odontocetes

2008 ◽  
Vol 34 (3) ◽  
pp. 288-302 ◽  
Author(s):  
Julie N. Oswald ◽  
Shannon Rankin ◽  
Jay Barlow
Keyword(s):  
Geographic Variation
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