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Based on the Trivers-Willard model, Clutton-Brock hypothesized that the sex ratio of mammalian offspring may change according to maternal condition, where high-ranked females should produce more male offspring and low-ranked females should produce more female offspring. [19] This is based on the assumption that high-ranked females are in better ...
Since carotenoid-based ornamentation suggests mate quality, female two-spotted guppies that develop colorful orange bellies during breeding season are considered favorable to males. [60] The males invest heavily in offspring during incubation, which leads to the sexual preference in colorful females due to higher egg quality.
The XO sex-determination system (sometimes referred to as X0 sex-determination system) is a system that some species of insects, arachnids, and mammals use to determine the sex of offspring. In this system, there is only one sex chromosome, referred to as X. Males only have one X chromosome (XO), while females have two
In humans and many other species of animals, the father determines the sex of the child. In the XY sex-determination system, the female-provided ovum contributes an X chromosome and the male-provided sperm contributes either an X chromosome or a Y chromosome, resulting in female (XX) or male (XY) offspring, respectively.
Some chromosomal sex determination systems in animals. A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. [1] Most organisms that create their offspring using sexual reproduction have two common sexes and a few less common intersex variations.
Gorilla Great reed warbler. When two animals mate, they both share an interest in the success of the offspring, though often to different extremes. Unless the male and female are perfectly monogamous, meaning that they mate for life and take no other partners, even after the original mate's death, the amount of parental care will vary. [7]
A harem is an animal group consisting of one or two males, a number of females, and their offspring. The dominant male drives off other males and maintains the unity of the group. If present, the second male is subservient to the dominant male.
Relatedness coefficients in haplodiploid organisms are as follows, assuming that a female has only mated once. These ratios apply, for example, throughout a bee hive, unless some laying workers produce offspring, which will all be males from unfertilised eggs: in that case, average relatedness will be lower than shown.