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
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
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
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
Ecology
Keryea Soong, Guan-Lin Yu, Chia-Hsuan Hsu, Gwo-Liang Chang, Shi-Jie Lin
Summary: A study on sea urchins in southern Taiwan revealed biased sex ratios, with higher mortality rates among females possibly causing the imbalance. The hypotheses of Sampling Bias and Innate mechanisms failed to explain the phenomenon, while the Differential Mortality Hypothesis provided a more plausible explanation for the skewed sex ratios observed in the population.
REGIONAL STUDIES IN MARINE SCIENCE
(2021)
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
Behavioral Sciences
David E. Ausband
Summary: Offspring sex ratios in gray wolves in Idaho are male-biased, reflecting sex-biased dispersal in the population. This may be a strategy used by breeding females to reduce future local resource competition. Individual, group, and population characteristics were not significantly associated with offspring sex ratios.
BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY
(2022)
Article
Ecology
Susumu Chiba, Aya Iwamoto, Seina Shimabukuro, Hiroyuki Matsumoto, Karin Inoue
Summary: Adult sex ratio (ASR) is crucial for population management, but its impact on population dynamics is still not well understood. This study investigated the effect of biased ASR on reproductive success in a decapod crustacean. The results showed that an increase in the proportion of males in mating groups led to a decrease in the number of eggs carried by females. This negative effect of ASR was observed at the population level when considering spawning success. Additionally, a male-biased ASR was found to reduce genetic diversity in the population. These findings highlight the importance of considering ASR in population management strategies.
JOURNAL OF ANIMAL ECOLOGY
(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
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
Ecology
Max R. Lambert, Tariq Ezaz, David K. Skelly
Summary: Population sex ratio is a key demographic factor affecting population dynamics. Sex ratios in amphibians vary during ontogeny, with the phenomenon of sex reversal complicating ontogenetic sex ratio variation. Our study showed that genotypic sex-biased mortality during tadpole development influences phenotypic sex ratio variation at metamorphosis, with sex reversal playing a minor and inconsistent role in shaping phenotypic sex ratios across populations. Further research is needed to determine the influence of sex-biased mortality on sex ratio variation across populations.
FRONTIERS IN ECOLOGY AND EVOLUTION
(2021)
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
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
Entomology
Z. G. Holditch, K. N. Ochoa, S. Greene, S. Allred, J. Baranowski, S. M. Shuster
Summary: Haplo-diploid sex determination in the parasitoid wasp Nasonia vitripennis allows females to adjust their brood sex ratios in order to minimize local mate competition. Previous studies have shown that sperm depletion affects sex allocation in this species.
JOURNAL OF INSECT SCIENCE
(2022)
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
Ellyssia T. Watts, Christopher N. Johnson, Scott Carver, Catherine Butler, Andrea M. Harvey, Elissa Z. Cameron
Article
Ecology
Johannes Masviken, Fredrik Dalerum, Sara A. O. Cousins
ECOLOGY AND EVOLUTION
(2020)
Article
Biodiversity Conservation
S. P. Finnegan, L. Galvez-Bravo, L. Silveira, N. M. Torres, A. T. A. Jacomo, G. B. Alves, F. Dalerum
Summary: Protected areas may not be large enough to sustain viable populations of large carnivores, leading to genetic isolation and demographic vulnerability. A study focusing on jaguar populations in Emas National Park in Brazil found that even a low number of immigrants could suppress the risk of extinction for populations estimated between 10-60 animals. Conservation efforts such as habitat corridors outside of protected areas could greatly reduce extinction risk for many large carnivore populations.
ANIMAL CONSERVATION
(2021)
Article
Environmental Sciences
James M. Pay, Todd E. Katzner, Clare E. Hawkins, Amelia J. Koch, Jason M. Wiersma, William E. Brown, Nick J. Mooney, Elissa Z. Cameron
Summary: Lead exposure was found in Tasmanian wedge-tailed eagles in Australia, with 100% of carcasses testing positive for lead and elevated concentrations in some samples. This highlights the threat of lead-based ammunition exposure to raptors and underscores the importance of addressing lead contamination in the ecosystem.
ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY
(2021)
Article
Engineering, Environmental
Fredrik Dalerum
Summary: The study found a negative correlation between the human-wolf conflict in Sweden and indicators of relative socioeconomic conditions, suggesting that geographic socioeconomic inequality may exacerbate such conflicts. Therefore, regional policies aimed at alleviating geographic socioeconomic inequities may create a more favorable environment for solving the human-wolf conflict in Sweden.
Article
Environmental Sciences
James M. Pay, Todd E. Katzner, Clare E. Hawkins, Leon A. Barmuta, William E. Brown, Jason M. Wiersma, Amelia J. Koch, Nick J. Mooney, Elissa Z. Cameron
Summary: The study revealed widespread exposure of the endangered apex predator Tasmanian wedge-tailed eagles in Australia to anticoagulant rodenticides, especially with high concentrations of second generation ARs. Exposed eagles were found in agricultural habitats with high human population density, and the main source of exposure was flocoumafen from agricultural suppliers.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Ornithology
James M. Pay, Todd E. Katzner, Jason M. Wiersma, William E. Brown, Clare E. Hawkins, Kirstin M. Proft, Elissa Z. Cameron
Summary: Research has shown that Tasmanian Wedge-tailed Eagles can be accurately sexed through a series of morphological measurements, with free-flying birds being sexed with 97.6% accuracy and late-stage nestlings with 95.4% accuracy. These findings provide valuable tools for studying sexual differences in behavior and causes of mortality in this endangered subspecies.
JOURNAL OF RAPTOR RESEARCH
(2021)
Article
Ecology
Jan Vigues, Karin Noren, Caitlin Wilkinson, Marianne Stoessel, Anders Angerbjorn, Fredrik Dalerum
Summary: Spatially synchronous fluctuations of animal populations have ecological consequences, especially in northern latitudes. This study examines the winter abundance of Norwegian lemmings in three mountain areas in northern Sweden and evaluates the relative importance of bottom-up and top-down regulation in generating spatial variation. The results suggest that variations in the relative strength of these regulatory processes contribute to differences in lemming winter abundances among the three areas.
Article
Biodiversity Conservation
James M. Pay, Toby A. Patterson, Kirstin M. Proft, Elissa Z. Cameron, Clare E. Hawkins, Amelia J. Koch, Jason M. Wiersma, Todd E. Katzner
Summary: Effective planning for species conservation often requires understanding habitat use. This study developed behavior-specific spatial habitat-use models using GPS telemetry data, providing valuable information for the management of threatened species. The study found that recently fledged Tasmanian wedge-tailed eagles selected different areas for perching, short-distance flight, and long-distance flight, with preferences for forest edges, steep topography, and areas further from forest edges, respectively.
BIOLOGICAL CONSERVATION
(2022)
Article
Biodiversity Conservation
Wendy C. Turner, Stephanie Periquet, Claire E. Goelst, Kimberlie B. Vera, Elissa Z. Cameron, Kathleen A. Alexander, Jerrold L. Belant, Claudine C. Cloete, Pierre du Preez, Wayne M. Getz, Robyn S. Hetem, Pauline L. Kamath, Marthin K. Kasaona, Monique Mackenzie, John Mendelsohn, John K. E. Mfune, Jeff R. Muntifering, Ruben Portas, H. Ann Scott, W. Maartin Strauss, Wilferd Versfeld, Bettina Wachter, George Wittemyer, J. Werner Kilian
Summary: Etosha National Park in Namibia is a dryland system with a rich history of wildlife conservation and research. Concerns have been raised about the impact of global change on wildlife conservation in this area. This article provides insight into the challenges facing wildlife conservation in this vulnerable dryland environment and emphasizes the need to integrate research and wildlife management.
GLOBAL ECOLOGY AND CONSERVATION
(2022)
Article
Ecology
Rocio Pena, Matthias Schleuning, Fredrik Dalerum, Isabel Donoso, Javier Rodriguez-Perez, Daniel Garcia
Summary: The study examined the influence of species abundance and trait-matching on plant-bird seed dispersal interactions. Both abundance and trait-matching were found to affect interaction frequencies and species-specific contributions to ecological functions.
BASIC AND APPLIED ECOLOGY
(2023)
Article
Ecology
Jordi Bartolome Filella, Christian Carlos Quispe Bonilla, Edgar Quispe, Fredrik Dalerum
Summary: Different non-invasive techniques, such as micro-histological analysis, have been used to determine herbivore diet composition. We developed an AI-based software application that can identify and count epidermal fragments from microscope slides, which is over 350 times faster than human observation. This study highlights the potential of AI for labor-intensive pattern recognition tasks in the study of herbivore diets.
EUROPEAN JOURNAL OF WILDLIFE RESEARCH
(2023)
Article
Ecology
Johannes Masviken, Love Dalen, Karin Noren, Fredrik Dalerum
Summary: Both abiotic and biotic conditions are important for biodiversity, but their relative importance may vary among diversity dimensions and spatial scales. This study examined the relative importance of abiotic and biotic conditions for three diversity dimensions of spider communities across different spatial scales. The results showed that the relationships among diversity dimensions were stronger at the local scale, and the influence of abiotic and biotic conditions varied among diversity dimensions but not consistently across spatial scales.
Article
Ecology
Johannes Masviken, Daniel Marquina, Karin Noren, Love Dalen, Fredrik Dalerum
Summary: Mountain topography leads to significant biodiversity variations in primary productivity due to climate-driven elevation gradients, making mountain areas useful for evaluating the ecological impacts of climate change. Arthropods, the most diverse animal phylum, play vital roles in ecosystems but we have limited knowledge about their variations along elevation gradients.
Article
Biology
Emma J. Godfrey, Elissa Z. Cameron, Graham J. Hickling
Summary: Social learning reduces trial-and-error learning costs and may contribute to trap and bait avoidance in invasive species. This study provides strong evidence of social learning by common brushtail possums and suggests important implications for pest control.