Sociosexuality and sex ratio: Sex differences and local markets

2005 ◽  
Vol 28 (2) ◽  
pp. 288-288
Author(s):  
John Lazarus
Keyword(s):  
Sex Differences ◽  
Sex Ratio ◽  
Local Level ◽  
Psychological Effects ◽  
Operational Sex Ratio ◽  
Know How ◽  
Males And Females ◽  
Mating Market ◽  
The Relationship ◽  
Ratio Measure

Operational sex ratio (OSR) is the correct sex ratio measure for predicting sociosexuality, but it is unclear whether this is the measure used. It would be valuable to know how OSR and sociosexuality correlate separately for males and females. The relationship between sociosexuality and OSR should also be examined with OSR measured at the local level of the mating market, where sex ratio must be having its psychological effects.

Sex Differences in the Relationship between Machiavellianism and Self-Disclosure

1978 ◽  
Vol 42 (3) ◽  
pp. 715-721 ◽  
Author(s):  
David E. Domelsmith ◽  
James T. Dietch
Keyword(s):  
College Students ◽  
Sex Differences ◽  
Negative Correlation ◽  
Self Disclosure ◽  
Men And Women ◽  
Willingness To Disclose ◽  
Males And Females ◽  
Individual Achievement ◽  
The Relationship ◽  
Existing Data

Previous research suggests that there should be a negative correlation between Machiavellianism (Mach) and willingness to reveal things about oneself. However, existing data are unclear and contradictory, especially regarding differences between males and females. College students (48 male, 77 female) completed measures of both Machiavellianism and self-disclosure, and the two sets of scores were correlated. As expected, Mach was significantly correlated with unwillingness to self-disclose among males. For the females, however, Mach was significantly correlated with willingness to disclose. The two correlations are significantly different. Culturally defined differences in the goals of men and women may account for the results. According to current stereotypes, men are oriented toward individual achievement, while die goals of women are more “social,” being popular, nurturant, skilled at getting along with others, etc. Women who accept these goals and who are willing to employ manipulative (Machiavellian) tactics to achieve them could use self-disclosure effectively, while it would be an ineffective strategy for men.

scholarly journals Investigating the interaction between inter-locus and intra-locus sexual conflict using hemiclonal analysis in Drosophila melanogaster

2021 ◽  
Author(s):  
Manas Geeta Arun ◽  
Tejinder Singh Chechi ◽  
Rakesh Meena ◽  
Shradha Dattaraya Bhosle ◽  
Srishti ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Ratio ◽  
Genetic Correlation ◽  
Empirical Evidence ◽  
Sexual Conflict ◽  
Genetic Basis ◽  
Operational Sex Ratio ◽  
Female Fitness ◽  
Male And Female ◽  
Males And Females

Divergence in the evolutionary interests of males and females leads to sexual conflict. Traditionally, sexual conflict has been classified into two types: inter-locus sexual conflict (IeSC) and intra-locus sexual conflict (IaSC). IeSC is modeled as a conflict over outcomes of intersexual reproductive interactions mediated by loci that are sex-limited in their effects. IaSC is thought to be a product of selection acting in opposite directions in males and females on traits with a common underlying genetic basis. While in their canonical formalisms IaSC and IeSC are mutually exclusive, there is growing support for the idea that the two may interact. Empirical evidence for such interactions, however, is limited. Here, we investigated the interaction between IeSC and IaSC in Drosophila melanogaster. Using hemiclonal analysis, we sampled 39 hemigenomes from a laboratory-adapted population of D. melanogaster. We measured the contribution of each hemigenome to adult male and female fitness at three different intensities of IeSC, obtained by varying the operational sex-ratio. Subsequently, we estimated the intensity of IaSC at each sex-ratio by calculating the intersexual genetic correlation for fitness and the proportion of sexually antagonistic fitness-variation. Our results indicate a statistically non-significant trend suggesting that increasing the strength of IeSC ameliorates IaSC in the population.

Sexual selection, the division of labor, and the evolution of sex differences

1998 ◽  
Vol 21 (3) ◽  
pp. 444-447 ◽  
Author(s):  
David C. Geary
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Sex Ratio ◽  
Division Of Labor ◽  
Operational Sex Ratio ◽  
Female Competition ◽  
Human Populations ◽  
Human Sex Differences ◽  
Male Choice ◽  
Relative Contribution

Sexual selection traditionally involves male-male competition and female choice, but in some species, including humans, sexual selection can also involve female-female competition and male choice. The degree to which one aspect of sexual selection or another is manifest in human populations will be influenced by a host of social and ecological variables, including the operational sex ratio. These variables are discussed in connection with the relative contribution of sexual selection and the division of labor to the evolution of human sex differences.

scholarly journals Reproductive aspects of the gulf pipefish, Syngnathus scovelli (Teleostei: Syngnathidae), from Southeastern Brazil

1999 ◽  
Vol 59 (1) ◽  
pp. 87-90 ◽  
Author(s):  
J. L. GASPARINI ◽  
R. L. TEIXEIRA
Keyword(s):  
Sex Ratio ◽  
Sandy Beach ◽  
Surf Zone ◽  
Southeastern Brazil ◽  
Immature Male ◽  
Female Sex ◽  
Total Length ◽  
Minimum Number ◽  
Males And Females ◽  
The Relationship

This study attempts to assess the relationship between fecundity and fertility of males and females of the gulf pipefish, Syngnathus scovelli. Specimens of this pipefish were collected in detached algae in the inner surf-zone of a dissipative sandy beach in southeastern Brazil. 97 specimens were collected, and they were associates to detached algae. From these, 14 were males, 36 females and 47 immature. Male-female sex ratio was 0.4:1, which was significantly different from the expected 1:1 ratio. Fish ranged from 43 to 98 mm TL (Fig. 1), and males and females showed similar size. Only 7 males were pregnants, while 9 females had hydrated oocytes. Minimum number of eggs/embryos in the pouch was 30 and the maximum 92. Minimum number of hydrated oocytes was 36, and the maximum was 165. The number of egg/embryos, and hydrated oocytes were weakly related to total length. It seems that the gulf pipefish occupy the inner surf-zone of the Praia do Iate are brought to the shallows accidentally when the specimens were inhabiting drifting vegetation.

Patterns of Gonadic Development and Operational Sex Ratio Promote Promiscuity of Euxesta bilimeki (Diptera:Ulidiidae)

2020 ◽  
Author(s):  
Christian L Rodríguez-Enríquez ◽  
Diana Pérez-Staples ◽  
Oscar Rios-Cardenas ◽  
Juan Rull
Keyword(s):  
Sex Ratio ◽  
Protein Content ◽  
Operational Sex Ratio ◽  
Mating Frequency ◽  
Body Protein ◽  
Protein Ingestion ◽  
Full Complement ◽  
Individual Mating ◽  
Males And Females ◽  
Testes Size

Abstract Promiscuous mating systems are widely distributed among animals and can be promoted by operational sex ratios (number of receptive adults; OSR). In populations where OSR is not biased towards any sex, the possibility that males and females mate with several individuals increases. For both sexes to synchronize in time and space for reproduction, adults should possess or simultaneously acquire nutrients required to reach sexual maturity. Among synovigenic (without a full complement of eggs at eclosion) species, nutrient acquisition, protein in particular, may influence the OSR. In the Agave fly Euxesta bilimeki (Hendel) (Diptera: Ulidiidae), both sexes engage in multiple mating and females frequently expel all or part of the ejaculate. Here, we assessed the effect of protein intake on gonadic development, and estimated OSR from field-collected individuals. Body protein content was compared between wild and laboratory individuals with access to different diets, and mating frequency and individual mating rate were analyzed for cohorts at a 1:1 sex ratio. Both sexes required protein ingestion for gonadic development, but there were no differences in protein content between field-collected males and males fed protein and sugar in the laboratory, despite the fact that males assigned 9.3% of their corporal weight to testicles. Euxesta bilimeki is a promiscuous species where both males and females mate multiply with one or several individuals in short periods of time; thus, large testes size may be linked to the need of voluminous ejaculate production, and might be further exacerbated by female ejaculate expulsion.

Sex differences may indeed exist for 3-D navigational abilities: But was sexual selection responsible?

1998 ◽  
Vol 21 (3) ◽  
pp. 443-444 ◽  
Author(s):  
Peter Frost
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Sex Ratio ◽  
Mortality Rates ◽  
Operational Sex Ratio ◽  
Hunter Gatherers ◽  
Selection Of

Polygyny does not necessarily entail sexual selection of men. All factors that affect the operational sex ratio must be considered. Data from contemporary hunter-gatherers indicate higher mortality rates in men than in women, and lost female reproductive time. If sexual selection did occur in ancestral hunter-gatherers, it was probably men selecting women and not women selecting men.

Short term changes in sex ratio and density alter coercive male mating tactics

Behaviour ◽  
2010 ◽  
Vol 147 (11) ◽  
pp. 1431-1442 ◽  
Author(s):  
James Cureton II ◽  
Raelynn Deaton ◽  
Rachel Martin
Keyword(s):  
Sex Ratio ◽  
Reproductive Activity ◽  
Operational Sex Ratio ◽  
Mating Frequency ◽  
Male Mating ◽  
Mating Tactics ◽  
Short Term ◽  
Classic Theory ◽  
Males And Females ◽  
The Impact

AbstractShort term fluctuations in operational sex ratio (OSR) and density can strongly influence male mating, often exacerbating conflict between males and females. Livebearing fishes of the genus Gambusia are ideal for investigating sexual conflict because males of all sizes mate coercively. In this study, we tested how short-term fluctuations in OSR and density influence coercive male mating behaviours. Specifically, we tested the prediction that as OSR becomes more female biased, males will mate with all available females. In contrast, as OSR becomes more male biased, male aggression will inhibit mating frequency. As predicted, males mated with more females as the number of available females increased. Moreover, males were less aggressive as the proportion of females increased and more aggressive as the number of males increased. This resulted in an inverse relationship between mating and aggression with OSR and density. Coercive males attempt to maximize their reproductive success by mating with all available females, which supports classic theory on the impact of OSR and density on reproductive activity.

scholarly journals Estimating adult sex ratios in nature

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160313 ◽  
Author(s):  
Sergio Ancona ◽  
Francisco V. Dénes ◽  
Oliver Krüger ◽  
Tamás Székely ◽  
Steven R. Beissinger
Keyword(s):  
Sex Differences ◽  
Sex Ratio ◽  
Evolutionary Biology ◽  
Adult Population ◽  
Sex Ratios ◽  
Estimation Methods ◽  
Spatial And Temporal Variation ◽  
Animal Populations ◽  
Adult Sex Ratio ◽  
Males And Females

Adult sex ratio (ASR, the proportion of males in the adult population) is a central concept in population and evolutionary biology, and is also emerging as a major factor influencing mate choice, pair bonding and parental cooperation in both human and non-human societies. However, estimating ASR is fraught with difficulties stemming from the effects of spatial and temporal variation in the numbers of males and females, and detection/capture probabilities that differ between the sexes. Here, we critically evaluate methods for estimating ASR in wild animal populations, reviewing how recent statistical advances can be applied to handle some of these challenges. We review methods that directly account for detection differences between the sexes using counts of unmarked individuals (observed, trapped or killed) and counts of marked individuals using mark–recapture models. We review a third class of methods that do not directly sample the number of males and females, but instead estimate the sex ratio indirectly using relationships that emerge from demographic measures, such as survival, age structure, reproduction and assumed dynamics. We recommend that detection-based methods be used for estimating ASR in most situations, and point out that studies are needed that compare different ASR estimation methods and control for sex differences in dispersal. This article is part of the themed issue ‘Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies’.

Operational Sex Ratio and Female Competition

2014 ◽  
Author(s):  
Haley M. Dillon ◽  
Lora E. Adair ◽  
Gary L. Brase
Keyword(s):  
Sex Ratio ◽  
Sex Ratios ◽  
Intrasexual Competition ◽  
Operational Sex Ratio ◽  
Female Competition ◽  
Future Directions ◽  
Adaptive Changes ◽  
Mating Market ◽  
Mating Behaviors ◽  
Theoretical Foundations

When there is a surplus of one sex in a population, members of that sex often compete against each other for access to the scarcer sex. This chapter reviews the theoretical foundations for this phenomenon, focusing on the concept of operational sex ratio (OSR; the ratio of viable and available males to females in a given mating market) versus overall sex ratio, as well as the phylogenetic evidence of sex ratios as an important factor influencing mating behaviors. Research on human OSR and its effects is a fairly recent development but has already led to findings that are generally coherent and consistent with the nonhuman evidence. The evidence to date indicates that people who find themselves in female-disadvantaged mating markets show systematic and adaptive changes in their behaviors, including increased female intrasexual competition. The chapter concludes with discussions of additional issues and future directions for research on OSR.

scholarly journals Operational Sex Ratio Predicts Binge Drinking Across U.S. Counties

2019 ◽  
Vol 17 (3) ◽  
pp. 147470491987468 ◽  
Author(s):  
Toe Aung ◽  
Susan M. Hughes ◽  
Liana S. E. Hone ◽  
David A. Puts
Keyword(s):  
Sex Ratio ◽  
Binge Drinking ◽  
Evolutionary Theory ◽  
Age Groups ◽  
Census Bureau ◽  
Operational Sex Ratio ◽  
Mixed Effects Models ◽  
County Level ◽  
The Relationship ◽  
Binge Drinker

Previous research suggests that binge drinking among young men serves as a “costly signal” to potential mates, such that the binge drinker is capable of bearing the harmful consequences of alcohol consumption. Here, we propose that binge drinking among young adults is conditionally dependent upon the signaler’s willingness to take risks, which is influenced by the local operational sex ratio (OSR). Using archived binge drinking estimates from 2009 to 2012 and Census Bureau records of OSRs, we tested the relationship between OSR and binge drinking rates at the county level across 3,143 U.S. counties against hypotheses drawn from evolutionary theory. Results from our mixed-effects models revealed that a higher overall OSR (i.e., more eligible men compared to women) was associated with higher male binge drinking rates but lower female binge drinking rates. A higher OSR particularly in the 20–29 and 50+ age groups predicted higher male binge drinking rates but lower female binge drinking rates. Our findings generally support predictions derived from evolutionary theory and suggest that binge drinking may function as a costly sexual signal, conditionally regulated by age and the local sex ratio.

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