Article
Ecology
Thibaut Barra, Vincent A. Viblanc, Claire Saraux, Jan O. Murie, F. Stephen Dobson
Summary: It has been found that mothers in better physical condition tend to produce male offspring, while those in worse condition tend to produce female offspring. Competitive interactions within families and relative maternal condition both influence the offspring sex ratio, with no strong support for any single-factor model.
Article
Obstetrics & Gynecology
Hanbo Wu
Summary: The study examined the relationship between maternal stress and sex ratio at birth over a period of 243 years in Sweden, finding that most measures of stress showed no statistically significant association with sex ratio at birth, not supporting the Trivers-Willard hypothesis.
HUMAN REPRODUCTION
(2021)
Article
Psychology, Biological
Valentin Thouzeau, Jeanne Bollee, Alejandrina Cristia, Coralie Chevallier
Summary: The Trivers-Willard hypothesis suggests that parents' bias towards sons or daughters depends on their condition. Numerous studies have been conducted to test this hypothesis in humans, with a total of 821 hypothesis tests reported in 87 articles. The overall results support the Trivers-Willard hypothesis. Additionally, the relationship between sex ratio and post-birth investment yielded mixed results and further research is recommended to evaluate the validity of the hypothesis and its underlying mechanisms.
EVOLUTION AND HUMAN BEHAVIOR
(2023)
Article
Behavioral Sciences
Sara A. Kaiser, Kathryn C. Grabenstein, T. Scott Sillett, Michael S. Webster
Summary: This study found that food availability does not affect offspring sex ratio in the migratory black-throated blue warbler, contradicting the predictions of the Trivers-Willard hypothesis. It highlights the challenges of studying mechanisms driving patterns in offspring sex allocation in migratory species.
BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY
(2023)
Article
Agriculture, Dairy & Animal Science
Radica Djedovic, Dragan Stanojevic, Vladan Bogdanovic, Dusica Ostojic Andric, Ljiljana Samolovac, Tamara Stamenic
Summary: This study aimed to investigate whether the sex of calves affects milk production in cows, and tested the Trivers-Willard hypothesis. The results showed that mothers invest more in female offspring by producing a higher milk yield, especially under better environmental conditions.
Article
Behavioral Sciences
Yan-Peng Li, Wei Ding, Zhi-Pang Huang, Ru-Liang Pan, Na Li, Guo-Peng Ren, Liang-Wei Cui, Qing-hua Cai, Wen Xiao
Summary: This study examines Trivers and Willard's hypothesis by analyzing a database of Chinese imperial families. The findings suggest that mothers with privileged conditions tend to produce more boys than girls.
BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY
(2022)
Article
Behavioral Sciences
Bojun Yi, Song Wang, Tao Sun, Ruoshuang Liu, Michael J. Lawes, Li Yang, Xuefeng Liu, Yifeng Li, Chengming Huang, Qihai Zhou, Penglai Fan
Summary: This study found that experienced mothers in captive populations of Francois' langur are more likely to produce female offspring. Although male offspring have higher mortality rates, the overall offspring mortality and interbirth interval are not influenced by maternal parity.
BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY
(2023)
Article
Ecology
Denyelle A. V. Kilgour, Courtney R. R. Linkous, Todd W. W. Pierson, Sarah Guindre-Parker
Summary: The Trivers-Willard hypothesis suggests that mothers adjust their offspring sex ratio based on their own condition and breeding environment. This study investigates the impact of urbanization on parental body condition and secondary offspring sex ratios in European starlings. The results indicate that parental body condition and site did not affect the production of male offspring, but the similarity of maternal and paternal CORT levels may increase the likelihood of successfully fledging sons.
FRONTIERS IN ECOLOGY AND EVOLUTION
(2022)
Article
Multidisciplinary Sciences
Marta Cholewa, Lukasz Jankowiak, Magdalena Szenejko, Andrzej Dybus, Przemyslaw Smietana, Dariusz Wysocki
Summary: Research on European Blackbirds has shown that parental age difference can impact offspring sex ratio and reproductive success. Young female Blackbirds tended to produce more sons when mating with older males, while older females produced more daughters when mating with younger males. The breeding success of male offspring increased with the father's age in a non-linear manner.
Article
Zoology
Y. Y. Chin, C. W. Rogers, E. K. Gee, K. J. Stafford, E. Z. Cameron
Summary: This study tests the Trivers-Willard Hypothesis (TWH) using a multivariable approach on thoroughbred mare breeding records. The findings support the TWH and demonstrate that maternal energy status is the dominant driver of sex allocation.
JOURNAL OF ZOOLOGY
(2023)
Article
Ecology
Alexander R. Yeo, James F. Hare
Summary: The study found that female Richardson's ground squirrels tend to produce more female offspring during their first litter, but this trend weakens with increasing litter size, and reverses to favor more male offspring in the third litter, indicating that Adaptive Sex Allocation is a product of interacting selection pressures.
Article
Behavioral Sciences
Pauline Toni, David M. Forsyth, Marco Festa-Bianchet
Summary: The study explored how environment and maternal caring ability affect offspring sex ratio. Maternal mass was found to be correlated with the production of sons.
BEHAVIORAL ECOLOGY
(2021)
Article
Ecology
Sarah M. Chinn, Timothy Smyser, James C. Beasley
Summary: Skewed sex ratios at birth are commonly observed in wild populations, but the extent to which parents can modulate offspring sex ratio for their own fitness remains unclear. In this study on wild pigs, we found evidence that factors such as wild boar ancestry, maternal age and condition, and resource availability may weakly contribute to male-biased sex ratio. However, adjusting litter size appeared to be the primary reproductive characteristic manipulated in wild pigs to increase fitness, rather than adjusting offspring sex ratio.
ECOLOGY AND EVOLUTION
(2023)
Article
Ecology
Luca Montana, Pauline Toni, Marco Festa-Bianchet
Summary: Studies have shown that paternal mass and size can influence offspring sex ratios, but do not affect postpartum sex-biased maternal expenditure. Therefore, research on offspring sex manipulation or maternal expenditure would benefit from explicitly considering the effects of paternal traits.
AMERICAN NATURALIST
(2022)
Article
Ecology
Matthew N. Zipple, Elizabeth A. Archie, Jenny Tung, Raphael S. Mututua, J. Kinyua Warutere, I. Long'ida Siodi, Jeanne Altmann, Susan C. Alberts
Summary: Over the past 50 years, various hypotheses have been proposed about the evolution of offspring sex ratio manipulation by mothers, but their success in explaining sex ratios in primates, including baboons, has been mixed. In this study, using a large sample size of baboons (n=1,372 offspring), four different hypotheses about the evolution of biased offspring sex ratios were tested, but no support for adaptive biasing of sex ratios was found. These results suggest that adaptive biasing of offspring sex does not occur in this population.
AMERICAN NATURALIST
(2023)
Article
Behavioral Sciences
Venla Berg, Virpi Lummaa, Ian J. Rickard, Karri Silventoinen, Jaakko Kaprio, Markus Jokela
Article
Anthropology
Ian J. Rickard
AMERICAN JOURNAL OF HUMAN BIOLOGY
(2012)
Article
Biology
Ian J. Rickard, Andrew M. Prentice, Anthony J. C. Fulford, Virpi Lummaa
Article
Biochemistry & Molecular Biology
Alexandre Courtiol, Ian J. Rickard, Virpi Lummaa, Andrew M. Prentice, Anthony J. C. Fulford, Stephen C. Stearns
Article
Geography, Physical
Jari Holopainen, Ian J. Rickard, Samuli Helama
Article
Multidisciplinary Sciences
Adam D. Hayward, Ian J. Rickard, Virpi Lummaa
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2013)
Article
Biology
Ian J. Rickard, Alexandre Courtiol, Andrew M. Prentice, Anthony J. C. Fulford, Tim H. Clutton-Brock, Virpi Lummaa
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2012)
Editorial Material
Biology
Ian J. Rickard, Alexandre Courtiol, Virpi Lummaa
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2012)
Article
Biology
Daniel Nettle, Willem E. Frankenhuis, Ian J. Rickard
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2013)
Editorial Material
Biology
Daniel Nettle, Willem E. Frankenhuis, Ian J. Rickard
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2014)
Article
Anthropology
Thomas V. Pollet, Joshua M. Tybur, Willem E. Frankenhuis, Ian J. Rickard
HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE
(2014)
Article
Psychology, Social
Markus Jokela, Alexandra Alvergne, Anna Rotkirch, Ian J. Rickard, Virpi Lummaa
PERSONALITY AND INDIVIDUAL DIFFERENCES
(2014)
Meeting Abstract
Anthropology
Alexandre Courtiol, Ian J. Rickard, Virpi Lummaa, Andrew M. Prentice, Anthony J. C. Fulford, Stephen C. Stearns
AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY
(2013)
Editorial Material
Psychology, Biological
Ian J. Rickard
BEHAVIORAL AND BRAIN SCIENCES
(2017)
Article
Psychology, Multidisciplinary
Ian J. Rickard, Willem E. Frankenhuis, Daniel Nettle
PERSPECTIVES ON PSYCHOLOGICAL SCIENCE
(2014)