Sex-Ratio Adjustment in Odocoileus: Does Local Resource Competition Play a Role?

1987 ◽  
Vol 129 (3) ◽  
pp. 452-457 ◽  
Author(s):  
M. Julian Caley ◽  
Thomas D. Nudds
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Local Resource Competition ◽  
Local Resource ◽  
Sex Ratio Adjustment

Sex Ratio and Local Resource Competition in a Prosimian Primate

Science ◽  
1978 ◽  
Vol 201 (4351) ◽  
pp. 163-165 ◽  
Author(s):  
A. B. CLARK
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Local Resource Competition ◽  
Local Resource

Sex Ratio in Primates: A Test of the Local Resource Competition Hypothesis

Oikos ◽  
1989 ◽  
Vol 56 (1) ◽  
pp. 132 ◽  
Author(s):  
Colin A. Chapman ◽  
Lauren J. Chapman ◽  
Karen S. Richardson
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Local Resource Competition ◽  
Local Resource ◽  
Competition Hypothesis

Sex Ratio and Local Resource Competition

1981 ◽  
Vol 117 (5) ◽  
pp. 796-797 ◽  
Author(s):  
John L. Hoogland
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Local Resource Competition ◽  
Local Resource

Local Resource Competition and Sex Ratio Variation in Birds

1995 ◽  
Vol 26 (2) ◽  
pp. 168 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Robert Montgomerie
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Local Resource Competition ◽  
Local Resource ◽  
Ratio Variation

Differential Dispersal, Local Resource Competition, and Sex Ratio Variation in Birds

1993 ◽  
Vol 141 (2) ◽  
pp. 263-280 ◽  
Author(s):  
Patricia Adair Gowaty
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Local Resource Competition ◽  
Local Resource ◽  
Ratio Variation

scholarly journals Sex Ratio Is Synergistically Modulated by Local Resource Competition and Enhancement: the Case of a Primitively Eusocial Wasp Under Female Philopatry

2021 ◽  
Author(s):  
Koji Tsuchida ◽  
Norio Ishiguro ◽  
Fuki Saito-Morooka ◽  
Jun-Ichi Kojima ◽  
Philip Spradbery
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Female Competition ◽  
Offspring Sex Ratio ◽  
Local Resource Competition ◽  
Local Resource ◽  
Female Philopatry ◽  
Primitively Eusocial Wasp ◽  
Before And After ◽  
Biased Sex Ratio

Abstract BackgroundIn animals, the offspring sex ratio is modulated by kin conflict and cooperation, and determining the ratio is a main concern in evolutionary biology. Male competition for access to local mates is predictive of a female-biased sex ratio in the offspring (local mate competition; LMC). Conversely, female competition for access to local resources is predictive of a male-biased sex ratio in the offspring (local resource competition; LRC). However, several factors other than competition should synergistically operate in real-world populations. In the Australian paper wasp Ropalidia plebeiana, LRC and local resource enhancement (LRE) may operate simultaneously. To determine whether this is the case, we evaluated colony sex ratios and examined whether competition and/or enhancement operates at the population level in this species. ResultsIn spring, many foundress queens started their colonies by comb-cutting, in which nest combs from the previous season were divided into several combs to be reused. Genetic relatedness among foundresses did not differ before and after comb-cutting. Relatedness among foundresses was 0.339, whereas relatedness among new foundresses was 0.589, revealing nearly functional monogyny. The global FST value calculated with mtDNA markers was higher than that calculated with microsatellite markers, even after we corrected for differences in effective population sizes between sexes. This finding indicates female philopatry, which was also confirmed by mark–release–recapture before and after the hibernation of new foundresses. The colony sex ratio of reproductives became slightly biased toward males in larger colonies. In addition, both the number of foundresses and number of workers were positively associated with the number of reproductives, which indicates that LRE was also operating.ConclusionsOur results suggest that although the population structure seems to meet the requirements of LRC, the sex ratio is not modulated solely by LRC. Instead, the availability of female helpers at the founding stage likely mitigates the sex ratio predicted by LRC through LRE. Thus, LRC at the founding stage and LRE at the reproductive stage synergistically modulate the colony sex ratio in R. plebeiana.

Sex-Ratio Variation in Marsupials

1989 ◽  
Vol 37 (3) ◽  
pp. 467 ◽  
Author(s):  
A Cockburn
Keyword(s):  
Sex Ratio ◽  
High Frequency ◽  
Sex Allocation ◽  
Resource Competition ◽  
Data Sets ◽  
Current Interest ◽  
Local Resource Competition ◽  
Mode Of Reproduction ◽  
Local Resource ◽  
Data Dredging

Many marsupials produce sex ratios biased towards male or female young. In several cases these changes are comfortably accommodated in the existing theory of sex allocation. Local resource competition and the Trivers-Willard hypothesis have been usefully applied to several data sets, and preliminary experimental work has supported the main tenets of theory. By contrast, several data sets lack explanation, and provide challenges to theoreticians. The high frequency of bias in marsupials does not result from data-dredging, as bias is usually reported in descriptive accounts of marsupial reproduction, without recourse to any theoretical or mechanistic explanations. It is not possible to distinguish whether the marsupial mode of reproduction is well suited to manipulate sex allocation, or whether it facilitates measurement of biased sex allocation. As for most eutherians and birds, the mechanism of prenatal sex allocation is unknown for any marsupial. However, the current interest in sex-determining mechanisms in marsupials suggests a profitable avenue for collaboration between geneticists, physiologists and evolutionary ecologists.

scholarly journals Local resource competition and sex ratio in the ant Cataglyphis cursor

2006 ◽  
Vol 17 (4) ◽  
pp. 569-574 ◽  
Author(s):  
Morgan Pearcy ◽  
Serge Aron
Keyword(s):  
Sex Ratio ◽  
Resource Competition ◽  
Local Resource Competition ◽  
Local Resource ◽  
Cataglyphis Cursor

scholarly journals Problems with primate sex ratios

2000 ◽  
Vol 355 (1403) ◽  
pp. 1627-1635 ◽  
Author(s):  
Craig Packer ◽  
D. Anthony Collins ◽  
Lynn E. Eberly
Keyword(s):  
Sex Ratio ◽  
Environmental Conditions ◽  
National Park ◽  
Resource Competition ◽  
Sex Ratios ◽  
Adaptive Variation ◽  
Gombe National Park ◽  
Local Resource Competition ◽  
Local Resource ◽  
Complex Processes

Birth sex ratios of baboons in Gombe National Park, Tanzania, show an overall male bias of ca . 20%, but there is no obvious explanation for this trend. Individual females did not alter their sex ratios according to persistent levels of local resource competition. Sex ratios showed an unexpected relationship between age and rank: subordinate females had more sons when they were young; dominant females had more sons when they were old. The sex ratio of low–ranking females also varied with the severity of environmental conditions during pregnancy. Our findings suggest that mammalian sex ratios might be the product of more complex processes than is generally recognized or that sex–determining mechanisms impose sufficient constraints to prevent adaptive variation in all contexts.

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