THE LENGTH OF GROWING SEASON AND ADULT SEX RATIO AFFECT SEXUAL SIZE DIMORPHISM IN MOOSE

Ecology ◽  
2006 ◽  
Vol 87 (3) ◽  
pp. 745-758 ◽  
Author(s):  
Mathieu Garel ◽  
Erling Johan Solberg ◽  
Bernt-Erik SÆther ◽  
Ivar Herfindal ◽  
Kjell-Arild Høgda
Keyword(s):  
Sex Ratio ◽  
Sexual Size Dimorphism ◽  
Growing Season ◽  
Size Dimorphism ◽  
Adult Sex Ratio

scholarly journals Evolution of sexual size dimorphism and its relationship with sex ratio in carabid beetles of Genus Ceroglossus Solier

2013 ◽  
Vol 59 (6) ◽  
pp. 769-777 ◽  
Author(s):  
Hugo A. Benítez ◽  
Jorge Avaria-Llautureo ◽  
Cristian B. Canales-Aguirre ◽  
Viviane Jerez ◽  
Luis E. Parra ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Sexual Size Dimorphism ◽  
Phylogenetic Signal ◽  
Comparative Method ◽  
Carabid Beetles ◽  
Entire Group ◽  
Geometrical Shape ◽  
Specific Level ◽  
Size Dimorphism ◽  
Morphological Studies

Abstract Although the degree of mate competition, given extreme differences in sex ratio, explains much of the pattern of male-biased size dimorphism among diverse taxa, it fails for some species which have potential for intense male competition for mates and yet exhibit little or no sexual size dimorphism (SSD). This fact suggest that species with low SSD should be express the effect of evolutionary pressure in non-obvious geometrical shape promoted by sex ratio in an evolutionary time scale. To evaluate this hypothesis we used phylogenetic comparative method in a Bayesian framework to investigate the evolution of SSD and the role of sex ratio at inter-specific level in the species of Ceroglossus (Coleoptera: Carabidae). In our results the proportion farthest from 1:1 is associated with more disparate body shape, even though the entire group has minimum variation in sex ratio, which is an intrinsic life history character of this group considering its phylogenetic conservatism or phylogenetic signal. We suggest that the sex ratio has determined the dimorphism degree during evolution of this group, since both traits have increased or decreased together during the species divergence (i.e. positive phylogenetic correlation: r2≈0.85). We suggest that morphological studies of SSD will benefit from using comparative method with Bayesian approaches to assess the effect of phylogenetic history and its uncertainty. Finally, this will be allow to researchers to quantify the uncertainty of specific evolutionary hypotheses accounting for observed sexual dimorphism patterns.

Male–male contests for mates, sexual size dimorphism, and sex ratio in a natural population of a solitary parasitoid

2013 ◽  
Vol 100 ◽  
pp. 1-8 ◽  
Author(s):  
Margarete V. Macedo ◽  
Ricardo F. Monteiro ◽  
Mariana P. Silveira ◽  
Peter J. Mayhew
Keyword(s):  
Sex Ratio ◽  
Natural Population ◽  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Solitary Parasitoid ◽  
Male Contests

Sexual size dimorphism and food requirements of nestling birds

1993 ◽  
Vol 71 (12) ◽  
pp. 2541-2545 ◽  
Author(s):  
David J. Anderson ◽  
Jo Reeve ◽  
Juan E. Martinez Gomez ◽  
Wesley W. Weathers ◽  
Siobhan Hutson ◽  
...  
Keyword(s):  
Gender Difference ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Sexual Size Dimorphism ◽  
Positive Association ◽  
Size Dimorphism ◽  
American Kestrels ◽  
Sex Allocation Theory ◽  
Strong Positive Association ◽  
And Gender

The food requirements of dependent sons and daughters have important implications for evolution of the sex ratio, according to current sex allocation theory. We studied food requirements of nestling American kestrels (Falco sparverius), a moderately size-dimorphic falcon, by hand-feeding 61 birds from hatching to fledging. Daughters, the larger gender, consumed 6.99% more food than did sons. Sons did not have higher energy expenditure from higher effort during sibling competition than daughters did, so parents must supply more food to satisfy daughters' needs than to satisfy sons'. A review of all related studies shows a strong positive association between the degree of sexual size dimorphism and gender difference in food requirements.

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