The Behavioral Ecology of Sex Tourism: The Consequences of Skewed Sex Ratios

2020 ◽  
pp. 004728752094610
Author(s):  
Florian Kock
Keyword(s):  
Sex Ratio ◽  
Behavioral Ecology ◽  
Sex Ratios ◽  
Reproductive Age ◽  
Operational Sex Ratio ◽  
Future Research ◽  
Sex Tourism ◽  
Same Sex ◽  
Biological Perspective ◽  
Attitudes Toward Sex

The operational sex ratio (i.e., the ratio of reproductive-age females to males in a population) shapes both animal and human behavior in important ways. Drawing on research in evolution and ecology, the author proposes that a local male-skewed sex ratio (i.e., a surplus of males) influences local men’s attitudes toward sex tourism. Analyzing historical field (study 1) and experimental data (study 2), the author demonstrates that male-skewed sex ratios increase men’s sex tourism rationalization and intent, while women’s predispositions are not sensitive to sex ratios. Sex tourism is explained as a subconscious ecological plasticity in response to perceived increased intensities of same-sex competition for mates, signaled by male-skewed sex ratios. The findings demonstrate a link between mating ecologies and sex tourism, with the latter serving as a compensatory behavior of same-sex mating competition. This research contributes a novel, biological perspective on sex tourism with implications for future research and practice.

scholarly journals Sex Chromosome Meiotic Drive in Stalk-Eyed Flies

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1169-1180 ◽  
Author(s):  
Daven C Presgraves ◽  
Emily Severance ◽  
Gerald S Willrinson
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Operational Sex Ratio ◽  
Genetic Modifiers ◽  
Ratio Distortion ◽  
The Impact ◽  
Sex Ratio Distortion

Meiotically driven sex chromosomes can quickly spread to fixation and cause population extinction unless balanced by selection or suppressed by genetic modifiers. We report results of genetic analyses that demonstrate that extreme female-biased sex ratios in two sister species of stalk-eyed flies, Cyrtodiopsis dalmanni and C. whitei, are due to a meiotic drive element on the X chromosome (Xd). Relatively high frequencies of Xd in C. dalmanni and C. whitei (13–17% and 29%, respectively) cause female-biased sex ratios in natural populations of both species. Sex ratio distortion is associated with spermatid degeneration in male carriers of Xd. Variation in sex ratios is caused by Y-linked and autosomal factors that decrease the intensity of meiotic drive. Y-linked polymorphism for resistance to drive exists in C. dalmanni in which a resistant Y chromosome reduces the intensity and reverses the direction of meiotic drive. When paired with Xd, modifying Y chromosomes (Ym) cause the transmission of predominantly Y-bearing sperm, and on average, production of 63% male progeny. The absence of sex ratio distortion in closely related monomorphic outgroup species suggests that this meiotic drive system may predate the origin of C. whitei and C. dalmanni. We discuss factors likely to be involved in the persistence of these sex-linked polymorphisms and consider the impact of Xd on the operational sex ratio and the intensity of sexual selection in these extremely sexually dimorphic flies.

Conclusion

2017 ◽  
Author(s):  
Gregory L. Carter ◽  
Maryanne L. Fisher
Keyword(s):  
Sex Ratio ◽  
Operational Sex Ratio ◽  
Future Research ◽  
Female Competition ◽  
Mate Poaching ◽  
Attitudes And Behaviors ◽  
Theoretical Perspectives ◽  
Wide Range ◽  
Mate Copying

This handbook has presented a wide range of theoretical perspectives on the motivations, attitudes, and behaviors involved in female competition. Using a metatheoretical framework, the contributors have examined how, when, and why women compete. This conclusion articulates the book’s main themes, beginning with evidence regarding women as active, competitive individuals and the value of mating information, addressing topics such as women’s competitive choices regarding mate copying, mate poaching, and mate retention. It then considers the role of intrasexual aggression in adolescence in relation to dating and reproduction, the importance of Operational Sex Ratio (OSR) to female competition, the concept of cooperative mothering or allomothering, and infanticide. It also discusses women as competitors in both traditional and novel social arenas as well as the role of women’s physiology in their competitive behaviors. Finally, it suggests directions for future research on topics that warrant further scrutiny.

scholarly journals Sex roles and adult sex ratios: insights from mammalian biology and consequences for primate behaviour

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160321 ◽  
Author(s):  
Peter M. Kappeler
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Social Organization ◽  
Sex Roles ◽  
Paternal Care ◽  
Sex Role ◽  
Sex Ratios ◽  
Theoretical Models ◽  
Operational Sex Ratio ◽  
Minimum Length

Theoretical models and empirical studies in various taxa have identified important links between variation in sex roles and the number of adult males and females (adult sex ratio (ASR)) in a population. In this review, I examine these relationships in non-human primates. Because most existing theoretical models of the evolution of sex roles focus on the evolutionary origins of sex-biased behaviour, they offer only a general scaffold for predicting variation in sex roles among and within species. I argue that studies examining sex role variation at these more specific levels need to take social organization into account to identify meaningful levels for the measurement of ASR and to account for the fact that ASR and sex roles mutually influence each other. Moreover, taxon-specific life-history traits can constrain sex role flexibility and impact the operational sex ratio (OSR) by specifying the minimum length of female time outs from reproduction. Using examples from the primate literature, I highlight practical problems in estimating ASR and OSR. I then argue that interspecific variation in the occurrence of indirect forms of paternal care might indeed be linked to variation in ASR. Some studies also indicate that female aggression and bonding, as well as components of inter-sexual relationships, are sensitive to variation in ASR. Thus, links between primate sex roles and sex ratios merit further study, and such studies could prompt the development of more specific theoretical models that make realistic assumptions about taxon-specific life history and social organization. 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 Culled males, infant mortality and reproductive success in a pre-industrial Finnish population

2015 ◽  
Vol 282 (1799) ◽  
pp. 20140835 ◽  
Author(s):  
Tim A. Bruckner ◽  
Samuli Helle ◽  
Elisabeth Bolund ◽  
Virpi Lummaa
Keyword(s):  
Reproductive Success ◽  
Infant Mortality ◽  
Sex Ratio ◽  
Sex Ratios ◽  
Male Infant ◽  
In Utero ◽  
Reproductive Age ◽  
Empirical Literature ◽  
Lifetime Reproductive Success ◽  
Natural Fertility

Theoretical and empirical literature asserts that the sex ratio (i.e. M/F) at birth gauges the strength of selection in utero and cohort quality of males that survive to birth. We report the first individual-level test in humans, using detailed life-history data, of the ‘culled cohort’ hypothesis that males born to low annual sex ratio cohorts show lower than expected infant mortality and greater than expected lifetime reproductive success. We applied time-series and structural equation methods to a unique multigenerational dataset of a natural fertility population in nineteenth century Finland. We find that, consistent with culled cohorts, a 1 s.d. decline in the annual cohort sex ratio precedes an 8% decrease in the risk of male infant mortality. Males born to lower cohort sex ratios also successfully raised 4% more offspring to reproductive age than did males born to higher cohort sex ratios. The offspring result, however, falls just outside conventional levels of statistical significance. In historical Finland, the cohort sex ratio gauges selection against males in utero and predicts male infant mortality. The reproductive success findings, however, provide weak support for an evolutionarily adaptive explanation of male culling in utero .

Does perceived sex ratio influence intrasexual competitiveness in women?

2020 ◽  
Author(s):  
Thomas Richardson
Keyword(s):  
Sex Ratio ◽  
Statistical Power ◽  
Sex Ratios ◽  
Facial Attractiveness ◽  
Single Women ◽  
Operational Sex Ratio ◽  
Type I ◽  
Double Blind ◽  
Future Career ◽  
Biased Sex Ratio

The operational sex ratio has been shown to influence a variety of behaviours in humans and non-human animals, particularly relating to intrasexual competition. One way females compete for mates is by derogating other women’s attractiveness. Recent studies have shown that priming participants with different sex ratios can induce sex ratio effects on behaviour. In a pre-registered, double blind experiment, 71 single women came to the lab twice and were primed with either a favourable (many men) or unfavourable (few men) sex ratio. I assessed whether unfavourable sex ratios increased self reported intrasexual competitiveness, as well as competitor derogation in the form of decreased ratings of female facial attractiveness and kindness. I also assessed whether they expressed less choosiness by rating male faces as more attractive. I tested whether any sex ratio effects are weaker for more attractive women. Finally, I attempted to replicate previous work suggesting that a male biased sex ratio increases women's preference for their future career over their future family. Despite having higher statistical power than most previous studies of this type, I did not find evidence for any of the hypothesised effects and failed to replicate 2 previous findings. The data indicated that the sex ratio manipulation likely did not work.

scholarly journals Do Local Sex Ratios Approximate Subjective Partner Markets?

Human Nature ◽  
2021 ◽  
Author(s):  
Andreas Filser ◽  
Richard Preetz
Keyword(s):  
Sex Ratio ◽  
Sex Ratios ◽  
Population Data ◽  
Future Research ◽  
Relationship Formation ◽  
Logistic Regression Models ◽  
Fine Grained ◽  
Adult Sex Ratio ◽  
And Behavior ◽  
Partner Market

AbstractSex ratios have widely been recognized as an important link between demographic contexts and behavior because changes in the ratio shift sex-specific bargaining power in the partner market. Implicitly, the literature considers individual partner market experiences to be a function of local sex ratios. However, empirical evidence on the correspondence between subjective partner availability and local sex ratios is lacking so far. In this paper, we analyzed how closely a set of different local sex ratio measures correlates with subjective partner market experiences. Linking a longitudinal German survey to population data for different entities (states, counties, municipalities), we used multilevel logistic regression models to explore associations between singles’ subjective partner market experiences and various operationalizations of local sex ratios. Results suggest that local sex ratios correlated only weakly with subjective partner market experiences. Adult sex ratios based on broad age brackets, including those for lower-level entities, did not significantly predict whether individuals predominantly met individuals of their own sex. More fine-grained, age-specific sex ratios prove to be better predictors of subjective partner market experiences, in particular when age hypergamy patterns were incorporated. Nevertheless, the respective associations were only significant for selected measures. In a complementary analysis, we illustrate the validity of the subjective indicator as a predictor of relationship formation. In sum, our results suggest that subjective partner availability is not adequately represented by the broad adult sex ratio measures that are frequently used in the literature. Future research should be careful not to equate local sex ratios and conscious partner market experiences.

scholarly journals Do local sex ratios approximate subjective partner markets? Evidence from the German Family Panel

2019 ◽  
Author(s):  
Andreas Filser ◽  
Richard Preetz
Keyword(s):  
Sex Ratio ◽  
Scientific Reasoning ◽  
Sex Ratios ◽  
Social Consequences ◽  
Event History ◽  
Future Research ◽  
Multilevel Regression ◽  
Relationship Formation ◽  
Partner Market ◽  
Market Indicator

A growing body of evidence suggests that imbalanced local sex ratios are correlated with social consequences, including the pattern and timing of union formation, fertility and relationship stability. Scholars have argued that these findings can be understood as a result of imbalances in the bargaining power the respective sex holds in male- or female-skewed regions, but they remain vague on the underlying mechanisms. Specifically, the literature implicitly considers individual partner market experiences to be a function of local sex ratios. However, empirical evidence on the correspondence between subjective partner availability and local sex ratios remains scarce. This study addresses this gap by linking individual-level German longitudinal survey data (pairfam) with local sex ratios from population data for different entities (states, counties, and municipalities). Using multilevel regression models, this paper analyses the correlations between a subjective partner market indicator and a variety of local sex ratio measures. Moreover, an event history analysis explored how either indicator relates transitions into relationships. Results revealed that none of the local sex ratio measures, including those for narrow age ranges and/or lower level administrative entities, significantly predicted whether individuals predominantly met individuals of their own sex. Event history models yielded significant correlations between this subjective partner market indicator and relationship formation for both genders, substantiating the validity of the subjective indicator. For local sex ratios, results revealed an additional association between local sex ratios and female relationship formation when the sex ratios were adjusted for age hypergamy. Male relationship formation was uncorrelated with any local sex ratio. Both evolutionary and social scientific reasoning on the consequences of sex ratio imbalances rest on assumptions of subjective partner availability that may not be adequately represented by local sex ratios. Future research should be careful not to equate local sex ratios and conscious partner market experiences.

scholarly journals Sex-specific deaths in Norway and Sweden during the COVID-19 pandemic: Did mandates make a difference?

2021 ◽  
pp. 140349482110100
Author(s):  
Ralph Catalano
Keyword(s):  
Sex Ratio ◽  
Infection Control ◽  
Temporal Variation ◽  
Risky Behavior ◽  
Control Strategies ◽  
Sex Ratios ◽  
Female Mortality ◽  
All Cause Mortality ◽  
Societal Expectations ◽  
Male To Female

Aims: To determine whether differences between Norway’s and Sweden’s attempts to contain SARS-CoV-2 infection coincided with detectably different changes in their all-cause mortality sex ratios. Measuring temporal variation in the all-cause mortality sex ratio before and during the pandemic in populations exposed to different constraints on risky behavior would allow us to better anticipate changes in the ratio and to better understand its association with infection control strategies. Methods: I apply time Box–Jenkins modeling to 262 months of pre-pandemic mortality sex ratios to arrive at counterfactual values of 10 intra-pandemic ratios. I compare counterfactual to observed values to determine if intra-pandemic ratios differed detectably from those expected as well as whether the Norwegian and Swedish differences varied from each other. Results: The male to female mortality sex ratio in both Norway and Sweden increased during the pandemic. I, however, find no evidence that the increase differed between the two countries despite their different COVID-19 containment strategies. Conclusion: Societal expectations of who will die during the COVID-19 pandemic will likely be wrong if they assume pre-pandemic mortality sex ratios because the intra-pandemic ratios appear, at least in Norway and Sweden, detectably higher. The contribution of differences in policies to reduce risky behavior to those higher ratios appears, however, small.

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