In the adaptation view, rape is a facultative reproductive strategy, meaning that rape is the result of natural selection favoring men who commit rape when its evolutionary benefits in terms of producing offspring outweigh its evolutionary costs (such as decreases in the number of offspring produced because of injury or punishment).
Fitness decreases with the variance in offspring number (ν v i u ), increases with the variance in offspring number produced by the remaining individuals in the population (∑ k ≠ i ν v k u and ∑ k ≠ i ∑ l ≠ i ρ v k l u ), and decreases with the covariance between the number of offspring produced and that of the remaining individuals in the population (∑ k ≠ i ρ v i k u ).
Importantly, Kimura did not consider variations in the number of offspring per individual.
Based on a large dataset of number of offspring versus body mass for mammals and birds, Janis & Carrano (1992) noticed that the number of offspring decreased significantly with body size for mammals while this was not the case in birds, where it remained constant.
Reproductive failure accompanied by imposex in females could result in extirpation of the B. japonica population within several years because the number of offspring produced by adult B. japonica in the population is likely to continue to decrease.
The number of offspring per father increased significantly (2-sample T 53 = −2.49, P = 0.016) from pre- (4.04±1.9 standard deviation [SD]) to post-treatment offspring cohorts (5.3±2.29 SD), whereas the number of offspring per mother decreased from pre- (4±1.33 SD) to post-treatment offspring cohorts (3.95±2.24 SD), but not significantly (T 51 = 0.1, P = 0.922).
We performed an ordinal logistic regression analysis to assess whether the number of offspring and the increased number of alleles in offspring (as compared to the allele number in the mother and the father contributing most to the offspring in each brood) depend on the number of detected fathers in each brood, designating the number of offspring as the dependent variable.
Parity referred to the number of offspring.
These possible defects in early development could explain the detected decrease in the number of the born offspring of Cln1/5 dko mice.
However, having large sons can lead to an increase in developmental time and a decrease in the number of next clutch offspring.
The decrease in the number of hybrids from offspring to adults as well as the maintenance of species identity may be the result of the selection against hybrids [ 38] which acts in the ecological context of this forest.
