Offspring sex ratio in relation to maternal age and social rank in mountain goats (Oreamnos americanus)

2000 ◽  
Vol 49 (4) ◽  
pp. 260-265 ◽  
Author(s):  
Steeve D. Côté ◽  
Marco Festa-Bianchet
Keyword(s):  
Sex Ratio ◽  
Maternal Age ◽  
Social Rank ◽  
Offspring Sex Ratio ◽  
Oreamnos Americanus ◽  
Mountain Goats ◽  
Offspring Sex

Maternal age, paternal age, and litter size interact to affect the offspring sex ratio of German Shepherd dogs

2019 ◽  
Vol 135 ◽  
pp. 169-173
Author(s):  
Anna Carolina Lopes Martins ◽  
Marília Andreia Vaz ◽  
Max Mendes Macedo ◽  
Renato Lima Santos ◽  
Conrado Aleksander Barbosa Galdino ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Litter Size ◽  
Maternal Age ◽  
Paternal Age ◽  
German Shepherd ◽  
Offspring Sex Ratio ◽  
Offspring Sex

scholarly journals Sex Ratio at Birth: A Retrospective Audit of the Birth Records of a Nigerian Hospital

2015 ◽  
Vol 10 (1) ◽  
pp. 85-88
Author(s):  
AN Onyiriuka ◽  
EM Ikeanyi
Keyword(s):  
Sex Ratio ◽  
Birth Order ◽  
Maternal Age ◽  
Sex Ratio At Birth ◽  
Offspring Sex Ratio ◽  
North West ◽  
Benin City ◽  
Retrospective Audit ◽  
Offspring Sex ◽  
Catholic Hospital

Aims: The aim was to determine the sex ratio at birth in St Philomena Catholic Hospital (SPCH), Benin City, south-south, Nigeria and to assess its relationship with birth order and maternal age. Methods: In this retrospective cohort study, the records of all deliveries at St Philomena Catholic Hospital (SPCH), Benin City, Nigeria between 1st January, 2005 and 31st December, 2014 (10 years) were retrieved and analyzed. Stillbirths and infants with ambiguous genitalia were excluded in the analysis. Results: The total number of live-births during the 10-year period under review was 13,702 and these consisted of 7,007 males and 6,695 females, resulting in a sex ratio of 104.7:100 (approximately 1.05) at birth. The yearly sex ratios varied from 1.01 to 1.14. The maternal age and the birth order significantly influenced offspring sex ratio at birth (p < 0.001). The highest sex ratio was found among third-birth-order offspring and the lowest was found among offspring of fifth-birth order and above. Offspring of mothers aged 25-29 years had the highest sex ratio and those of mothers aged 40 years and above had the lowest sex ratio. Conclusions: The sex ratio at birth in south-south Nigeria is comparable to values obtained from south-west Nigeria but lower than that obtained from north-west Nigeria. The birth order and maternal age influenced the offspring sex ratio at birth.  

Offspring sex ratio in moose Alces alces in relation to paternal age: an experiment

2004 ◽  
Vol 10 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Bernt-Erik Sæther ◽  
Erling J. Solberg ◽  
Morten Heim ◽  
John E. Stacy ◽  
Kjetill S. Jakobsen ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Alces Alces ◽  
Paternal Age ◽  
Offspring Sex Ratio ◽  
Offspring Sex

Breeding system can affect the offspring sex ratio in Syrian hamsters

2011 ◽  
Vol 45 (1) ◽  
pp. 55-57 ◽  
Author(s):  
M O M Chelini ◽  
N L Souza ◽  
E Otta
Keyword(s):  
Sex Ratio ◽  
Breeding System ◽  
Offspring Sex Ratio ◽  
Syrian Hamsters ◽  
Offspring Sex

scholarly journals Is biasing offspring sex ratio adaptive? A test of Fisher's principle across multiple generations of a wild mammal in a fluctuating environment

2018 ◽  
Vol 285 (1891) ◽  
pp. 20181251 ◽  
Author(s):  
Andrea E. Wishart ◽  
Cory T. Williams ◽  
Andrew G. McAdam ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Adult Sex Ratio ◽  
Secondary Sex Ratio ◽  
North American Red Squirrels ◽  
Negative Frequency Dependent Selection ◽  
Fisher’S Principle

Fisher's principle explains that population sex ratio in sexually reproducing organisms is maintained at 1 : 1 owing to negative frequency-dependent selection, such that individuals of the rare sex realize greater reproductive opportunity than individuals of the more common sex until equilibrium is reached. If biasing offspring sex ratio towards the rare sex is adaptive, individuals that do so should have more grandoffspring. In a wild population of North American red squirrels ( Tamiasciurus hudsonicus ) that experiences fluctuations in resource abundance and population density, we show that overall across 26 years, the secondary sex ratio was 1 : 1; however, stretches of years during which adult sex ratio was biased did not yield offspring sex ratios biased towards the rare sex. Females that had litters biased towards the rare sex did not have more grandoffspring. Critically, the adult sex ratio was not temporally autocorrelated across years, thus the population sex ratio experienced by parents was independent of the population sex ratio experienced by their offspring at their primiparity. Expected fitness benefits of biasing offspring sex ratio may be masked or negated by fluctuating environments across years, which limit the predictive value of the current sex ratio.

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