The purpose of this study was to determine if male radiologists predominantly father daughters and, if so, to investigate the association between this skewed sex ratio of offspring and radiation exposure. Questionnaires completed by 586 male radiologists in Japan provided data regarding the radiologist'...
DESIGN: By aggregating mortality at each year of life for the 22 countries for those years for which reliable data were recorded (during the period 1850-1999), distinct patterns emerge. RESULTS: In the richer countries of the world, the male:female mortality ratio has been widening for all ...
The sexual system of the symbiotic shrimp Thor amboinensis is described, along with observations on sex ratio and host-use pattern of different populations. We used a comprehensive approach to elucidate the previously unknown sexual system of this shrimp. Dissections, scanning electron microscopy, size...
This study investigated, through large-scale statistical analysis of the global population, whether the human sex ratio is skewing worldwide, and if so, why and how it shifts, and the impact of any shift on human reproduction. A significant imbalance of the sex ratio was observed in the whol...
摘要: Background: We recently demonstrated that dwarf male plants are much more common among mosses than hitherto thought. Dwarf plants, producing functional male sexual organs occur in 1020% of the moss species worldwide.关键词:Andoa bryophyte gender ratio Isothecium Macaronesia male dwarfism My...
On the coast of Tamaulipas Sex determination was investigated in Cagle's map turtle, Graptemys caglei, which has a restricted distribution which is the southernmost of all Graptemys ... HMCG Chávez,TPHD Eduardo - 《Int.turtle Tort.soc.j》 被引量: 14发表: 1968年 Predicted Sex Ratio of Juv...
This study explores the relation of the human sex ratio at birth to four selected variables: calendar-year, color, maternal age, and parity of mother. In the analysis of variance, the sex ratio at birth is found to differ significantly by color, age of mother, and birth order of child....
In Japan, the ratio of never-married men to married men has risen rapidly since the second half of the 1980s. In this paper, we focus on the disruption of the gender balance, and on the effect that this and education level have on marriage behaviour. We confirmed that the rise in the...
Both the sex ratio and the extent of sexual size dimorphism (SSD) can have important implications for the mating system of a species. In particular, the sex that is limited (generally the female) is often the subject of intense competition, which can drive changes in behaviour and morphology...
In the absence of manipulation, both the sex ratio at birth and the population sex ratio are remarkably constant in human populations. Small alterations do occur naturally; for example, a small excess of male births has been reported to occur during and after war. The tradition of son preferen...