scholarly journals Sex differences in age-to-maturation relate to sexual selection and adult sex ratios in birds

2020 ◽  
Vol 4 (1) ◽  
pp. 44-53
Author(s):  
Sergio Ancona ◽  
András Liker ◽  
M. Cristina Carmona-Isunza ◽  
Tamás Székely
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Sex Ratios

Changing sex differences in undernutrition of African children: findings from Demographic and Health Surveys

2021 ◽  
pp. 1-11
Author(s):  
Michel Garenne ◽  
Susan Thurstans ◽  
André Briend ◽  
Carmel Dolan ◽  
Tanya Khara ◽  
...  
Keyword(s):  
Sex Differences ◽  
Health Surveys ◽  
Sex Ratios ◽  
Sub Saharan Africa ◽  
Demographic And Health Surveys ◽  
Growth Charts ◽  
Sub Saharan ◽  
Male To Female ◽  
Height For Age ◽  
Weight For Age

Abstract The study investigates sex differences in the prevalence of undernutrition in sub-Saharan Africa. Undernutrition was defined by Z-scores using the CDC-2000 growth charts. Some 128 Demographic and Health Surveys (DHS) were analysed, totalling 700,114 children under-five. The results revealed a higher susceptibility of boys to undernutrition. Male-to-female ratios of prevalence averaged 1.18 for stunting (height-for-age Z-score <−2.0); 1.01 for wasting (weight-for-height Z-score <−2.0); 1.05 for underweight (weight-for-age Z-score <−2.0); and 1.29 for concurrent wasting and stunting (weight-for-height and height-for-age Z-scores <−2.0). Sex ratios of prevalence varied with age for stunting and concurrent wasting and stunting, with higher values for children age 0–23 months and lower values for children age 24–59 months. Sex ratios of prevalence tended to increase with declining level of mortality for stunting, underweight and concurrent wasting and stunting, but remained stable for wasting. Comparisons were made with other anthropometric reference sets (NCHS-1977 and WHO-2006), and the results were found to differ somewhat from those obtained with CDC-2000. Possible rationales for these patterns are discussed.

scholarly journals Was facial width-to-height ratio subject to sexual selection pressures? A life course approach

2020 ◽  
Author(s):  
Carolyn R. Hodges-Simeon ◽  
Graham Albert ◽  
George B. Richardson ◽  
Timothy S. McHale ◽  
Seth M. Weinberg ◽  
...  
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Current Evidence ◽  
Facial Morphology ◽  
Facial Growth ◽  
Height Ratio ◽  
Lower Face ◽  
Male Adolescents ◽  
Classic Pattern ◽  
Facial Development

AbstractSexual selection researchers have traditionally focused on adult sex differences; however, the schedule and pattern of sex-specific ontogeny can provide insights unobtainable from an exclusive focus on adults. Recently, it has been debated whether facial width-to-height ratio (fWHR; bi-zygomatic breadth divided by midface height) is a human secondary sexual characteristic (SSC). Here, we review current evidence, then address this debate using ontogenetic evidence, which has been under-explored in fWHR research. Facial measurements collected from males and females aged 3 to 40 (Study 1; US, n=2449), and 7 to 21 (Study 2; Bolivia, n=179) were used to calculate three fWHR variants (which we call fWHRnasion, fWHRstomion, and fWHRbrow) and two other common facial masculinity ratios (facial width-to-lower-face-height ratio, fWHRlower, and cheekbone prominence). We test whether the observed pattern of facial development exhibits patterns indicative of SSCs, i.e. differential adolescent growth in either male or female facial morphology leading to an adult sex difference. Results showed that only fWHRlower exhibited both adult sex differences as well as the classic pattern of ontogeny for SSCs—greater lower-face growth in male adolescents relative to females. fWHRbrow was significantly wider among both pre- and post-pubertal males in the 2D sample; post-hoc analyses revealed that the effect was driven by large sex differences in brow height, with females having higher placed brows than males across ages. In both samples, all fWHR measures were inversely associated with age; that is, human facial growth is characterized by greater relative growth in the mid-face and lower face relative to facial width. This trend continues even into middle adulthood. BMI was also a positive predictor of most of the ratios across ages, with greater BMI associated with wider faces. Researchers collecting data on fWHR should target fWHRlower and fWHRbrow and should control for both age and BMI.

Synthesis and Outlook

2021 ◽  
pp. 153-161
Author(s):  
Ingo Schlupp
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sex Ratios ◽  
Empirical Work ◽  
Male Mate Choice ◽  
Female Ornamentation ◽  
Female Quality ◽  
Investment In Reproduction ◽  
Selection Research ◽  
Male Mate

In this final chapter I want to briefly recap what I presented in the previous chapters and provide a few ideas on what might be done in the future to move the field forward. All three factors I discussed as relevant in male mate choice—male investment in reproduction, sex ratios, and variability in partner quality—are still emerging fields in sexual selection research and need more theoretical and empirical work. I suggest that variability in female quality is more important and more complex than currently known. The same is true for sex ratios. On the other hand, I suggest that sheer investment in gametes may be a little less important than currently assumed. Most importantly we need to explore the interactions of these three pathways to male mate choice. Female competition and also female ornamentation are still somewhat enigmatic and both topics are likely to grow in importance for our understanding of sexual selection. I think considering male and female choice together, as well as female and male competition will ultimately provide a more complete picture of Darwinian sexual selection.

Sexual Selection, Receiver Biases, and the Evolution of Sex Differences

1998 ◽  
Vol 281 (5385) ◽  
pp. 1999-2003 ◽  
Author(s):  
M. J. Ryan
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Evolution Of Sex

Operational sex ratios and behavioural sex differences in a pipefish population

1994 ◽  
Vol 34 (6) ◽  
pp. 142-435 ◽  
Author(s):  
Amanda Vincent ◽  
Ingrid Ahnesj� ◽  
Anders Berglund
Keyword(s):  
Sex Differences ◽  
Sex Ratios ◽  
Operational Sex Ratios ◽  
Behavioural Sex Differences

Sexual selection does not provide an adequate theory of sex differences in aggression

2009 ◽  
Vol 32 (3-4) ◽  
pp. 276-277 ◽  
Author(s):  
Alice H. Eagly ◽  
Wendy Wood
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Social Role ◽  
Adequate Account ◽  
Selection Theory ◽  
Biosocial Theory ◽  
Adequate Theory ◽  
Sexual Selection Theory ◽  
Physical Attributes ◽  
Reproductive Activities

AbstractOur social role/biosocial theory provides a more adequate account of aggression sex differences than does Archer's sexual selection theory. In our theory, these sex differences arise flexibly from sociocultural and ecological forces in interaction with humans' biology, as defined by female and male physical attributes and reproductive activities. Our comments elaborate our theory's explanations for the varied phenomena that Archer presents.

scholarly journals Sex differences in lizard escape decisions vary with latitude, but not sexual dimorphism

2015 ◽  
Vol 282 (1805) ◽  
pp. 20150050 ◽  
Author(s):  
Diogo S. M. Samia ◽  
Anders Pape Møller ◽  
Daniel T. Blumstein ◽  
Theodore Stankowich ◽  
William E. Cooper
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Risk Taking ◽  
Reproductive Effort ◽  
Meta Analysis ◽  
Specific Behaviour ◽  
Underlying Mechanisms ◽  
Natural And Sexual Selection ◽  
Predator Behaviour ◽  
Latitudinal Effect

Sexual selection is a powerful evolutionary mechanism that has shaped the physiology, behaviour and morphology of the sexes to the extent that it can reduce viability while promoting traits that enhance reproductive success. Predation is one of the underlying mechanisms accounting for viability costs of sexual displays. Therefore, we should expect that individuals of the two sexes adjust their anti-predator behaviour in response to changes in predation risk. We conducted a meta-analysis of 28 studies (42 species) of sex differences in risk-taking behaviour in lizards and tested whether these differences could be explained by sexual dichromatism, by sexual size dimorphism or by latitude. Latitude was the best predictor of the interspecific heterogeneity in sex-specific behaviour. Males did not change their escape behaviour with latitude, whereas females had increasingly reduced wariness at higher latitudes. We hypothesize that this sex difference in risk-taking behaviour is linked to sex-specific environmental constraints that more strongly affect the reproductive effort of females than males. This novel latitudinal effect on sex-specific anti-predator behaviour has important implications for responses to climate change and for the relative roles of natural and sexual selection in different species.

scholarly journals Does sexual selection explain human sex differences in aggression?

2009 ◽  
Vol 32 (3-4) ◽  
pp. 249-266 ◽  
Author(s):  
John Archer
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Physical Aggression ◽  
Role Theory ◽  
Social Roles ◽  
Social Role ◽  
Conflicts Of Interest ◽  
Reproductive Competition ◽  
Threat Displays ◽  
Males And Females

AbstractI argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent with an alternative life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained.

Sex Ratios, Sexual Selection, and Sexual Dimorphism in Quails

1980 ◽  
Vol 44 (1) ◽  
pp. 198 ◽  
Author(s):  
David E. Brown ◽  
R. J. Gutierrez
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Ratios
Sign in / Sign up

Export Citation Format

Share Document