Articles tagged with Sex Ratios
A study found that mothers who gained weight between their first and second pregnancies were more likely to have a baby boy. The researchers analyzed data from over 220,000 women and discovered a significant association between increased maternal weight gain and an increased male-to-female sex ratio in the second pregnancy.
New research reveals that shorebirds' breeding systems are shaped by the battle over childcare responsibilities. The study found that parents with demanding young are more likely to stay together to help rear their offspring, while those with harder-to-raise young are more likely to fight for mating opportunities.
Researchers found that female domesticated canaries varied the size of their eggs in response to the attractiveness of the male's song. The study highlights the importance of behavioral stimuli for reproductive physiology. In this experiment, attractive songs led to larger eggs, but no difference was observed in brood sex ratio.
Researchers at Cornell University found that higher-than-normal progesterone levels in female chickens during the first meiosis significantly produce more females. The study suggests that female birds manipulate sex ratios to adapt to their environment and ensure the next generation has enough females to care for.
Researchers found a significant decline in female water voles at a Norfolk site, with radio-collars potentially linked to the change. The study suggests that local resource competition may drive sex-ratio shifts in stressed females.
Researchers investigate the impact of partnership status on human sex ratios at birth, shedding new light on this complex topic. The study reveals intriguing findings about the dynamics between relationships and sex ratios, with potential implications for our understanding of human behavior.
A new study found that many fig wasp species are cryptic, meaning they are genetically identical but belong to different host fig species. This challenges current ideas about the stability and evolution of mutualisms, strengthening other critical parts of modern evolutionary theory.
Researchers from Italy studied over 14,000 births and found a significant disparity in sex ratios between optimal and sub-optimal reproductive conditions. The study suggests that nature tries to compensate for the vulnerability of male babies by favoring them in favorable months.
A recent study has found that parental smoking around the time of conception is associated with a reduction in male births. The research suggests that exposure to cigarette smoke may affect sperm cells carrying the Y-chromosome, leading to lower male to female sex ratios. Smoking was found to impact sex ratios even when only the mother...
Researchers at North Carolina State University discovered that fire ant queens can alter the sex ratio of their colonies by limiting female eggs laid. This finding suggests a negotiated middle ground between queens and workers, who have competing interests in raising new colony members.