Sexual Dimorphism in Size, Relative Size of Testes, and Mating Systems in North American Voles

1990 ◽  
Vol 71 (4) ◽  
pp. 510-519 ◽  
Author(s):  
E. J. Heske ◽  
R. S. Ostfeld
Keyword(s):  
Sexual Dimorphism ◽  
North American ◽  
Mating Systems ◽  
Relative Size

Sexual Dimorphism and Food Habits in Three North American Accipiters

The Auk ◽  
1966 ◽  
Vol 83 (3) ◽  
pp. 423-436 ◽  
Author(s):  
Robert W. Storer
Keyword(s):  
Sexual Dimorphism ◽  
North American ◽  
Food Habits

The relationship between forelimb morphology and behaviour in North American carnivores (Carnivora)

1999 ◽  
Vol 77 (7) ◽  
pp. 1064-1074 ◽  
Author(s):  
Andrew N Iwaniuk ◽  
Sergio M Pellis ◽  
Ian Q Whishaw
Keyword(s):  
North American ◽  
Significant Relationship ◽  
Feeding Behaviour ◽  
Prey Capture ◽  
Relative Size ◽  
Independent Contrasts ◽  
Important Indicator ◽  
Predatory Behaviour ◽  
Olecranon Process ◽  
The Relationship

We tested the validity of previously described relationships between forelimb structure and behaviour in mammals by measuring the forelimbs of 22 species of North American carnivores. Nine ratios were calculated from these measurements and made independent of the effects of allometry and phylogeny through the use of log-transformed regressions and independent contrasts analysis. The ratios were then directly compared with two behavioural traits: arboreal locomotion and vertebrate predation. Only five of the nine ratios exhibited a significant relationship with arboreal locomotion and three with vertebrate predation. It was concluded that the brachial index, relative size of the olecranon process, and total forelimb robusticity may be reliable predictors of arboreal locomotion, and that the brachial index, relative size of the olecranon process, and radial robusticity may be accurate predictors of vertebrate predation. The data also suggest that the morphology of the lower forelimb may be an important indicator of prey-capture and feeding behaviour in carnivores and could be used in conjunction with craniodental variables to extrapolate predatory behaviour of extinct species.

Sexual Dimorphism in the Adipose Fin of Pacific Salmon (Oncorhynchus)

1983 ◽  
Vol 40 (11) ◽  
pp. 2019-2024 ◽  
Author(s):  
Terry D. Beacham ◽  
Clyde B. Murray
Keyword(s):  
Sexual Dimorphism ◽  
Chinook Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Relative Size ◽  
Correct Identification ◽  
Actual Amount ◽  
Adipose Fin

Male adipose fins of Oncorhynchus species were 30–50% larger than those of same-sized females, the actual amount depending on the species. Accuracy of classification of the standards ranged from 87% in chinook salmon (O. tshawytscha) to 98% in pink salmon (O. gorbuscha). Testing the method on new samples usually resulted in an accuracy of at least 90% correct identification of sex for any species. Relative size of the adipose fin should allow for easy and accurate external identification of the sexes of silver-bright Oncorhynchus.

Interspecific variation in sexual dimorphism in brain size in Nearctic ground squirrels (Spermophilus spp.)

2001 ◽  
Vol 79 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Andrew N Iwaniuk
Keyword(s):  
Sex Differences ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Ground Squirrel ◽  
Mating Systems ◽  
Resource Competition ◽  
Brain Size ◽  
Ground Squirrels ◽  
Detailed Knowledge ◽  
Size Dimorphism

A possible relationship between sexual dimorphism in brain size and mating system was investigated in five ground squirrel species: Spermophilus lateralis, S. tridecemlineatus, S. richardsonii, S. columbianus, and S. parryii. Relative brain size was measured by determining the endocranial volume of 247 ground squirrel skulls and regressing these values against two measurements of body size: mass and length. Analyses of covariation in the brain size / body size relationship within the five species revealed that sexual brain-size dimorphism occurs in three of the five species: S. lateralis, S. richardsonii, and S. tridecemlineatus. Application of a reduced major axis regression model indicated, however, that only S. lateralis and S. richardsonii exhibit significant sexual brain-size dimorphism. These findings suggest that the degree of sexual brain-size dimorphism is not directly correlated with variation in mating systems. Spatial abilities may play a role in the evolution of sexual brain-size dimorphism in ground squirrels, but the spatial requirements of mating systems appear to be insufficient. The possibility of sex differences in cognition, resource competition, and other variables as contributory factors to the evolution of sexual brain-size dimorphism is offered, but detailed knowledge of sex differences in the behaviour of ground squirrels is required to provide a definitive answer.

The Influence of Habitats on Mating Systems of North American Passerine Birds

Ecology ◽  
1966 ◽  
Vol 47 (1) ◽  
pp. 143-147 ◽  
Author(s):  
Jared Verner ◽  
Mary F. Willson
Keyword(s):  
North American ◽  
Mating Systems ◽  
Passerine Birds

Sexual Dimorphism and Mating Systems in Voles

1993 ◽  
Vol 74 (1) ◽  
pp. 230-233 ◽  
Author(s):  
R. S. Ostfeld ◽  
E. J. Heske
Keyword(s):  
Sexual Dimorphism ◽  
Mating Systems
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