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Examples of secondary sex characteristics in non-human animals include manes of male lions [4] and long feathers of male peafowl, the tusks of male narwhals, enlarged proboscises in male elephant seals and proboscis monkeys, the bright facial and rump coloration of male mandrills, horns in many goats and antelopes, [10] and the swollen upper ...
For example, in mammals, the SRY gene on the Y chromosome initiates testis development, but subsequent male sexual differentiation heavily relies on androgens. [86] Sexual Dimorphism: The combined effects of CASI and hormones contribute to the development of sexually dimorphic traits. In some cases, CASI may dictate cellular predispositions ...
Also not all male dimorphic traits are due to hormones like testosterone, instead they are a naturally occurring part of development, for example plumage. [78] In addition, the strong hormonal influence on phenotypic differences suggests that the genetic mechanism and genetic basis of these sexually dimorphic traits may involve transcription ...
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, males and females , and in other species, there are hermaphrodites , organisms that can function reproductively as either ...
Offspring have two sex chromosomes: an offspring with two X chromosomes (XX) will develop female characteristics, and an offspring with an X and a Y chromosome (XY) will develop male characteristics, except in various exceptions such as individuals with Swyer syndrome, that have XY chromosomes and a female phenotype, and de la Chapelle Syndrome ...
Couple of male mallard ducks in a nature reserve in Germany. For these animals, there is documented evidence of homosexual behavior of one or more of the following kinds: sex, courtship, affection, pair bonding, or parenting, as noted in researcher and author Bruce Bagemihl's 1999 book Biological Exuberance: Animal Homosexuality and Natural ...
Elephants can use their ears as threat displays in male-to-male competition. Sexual selection in mammals is a process the study of which started with Charles Darwin's observations concerning sexual selection, including sexual selection in humans, and in other mammals, [1] consisting of male–male competition and mate choice that mold the development of future phenotypes in a population for a ...
A study on the association of alpha males and females during the non-breeding season in wild Capuchin monkeys examined whether alpha males are the preferred mate for females and, secondly, whether female-alpha status and relationship to the alpha-male can be explained through the individual characteristics and or social network of the female. [4]