|
Sexual Bimaturism
Sexual bimaturism describes a difference in developmental timing between males and females of the same species. Sexual bimaturism can result in sexual dimorphism, but sexual dimorphism could also develop through differential rates of development. In many insects, the larval period of females is longer than that of males, and as a result of this extended growth period, these female insects are larger than their male conspecifics. Male simian primates are generally larger than females of the same species due in part to extended growth periods. Gorillas demonstrate a particularly high degree of sexual bimaturism. Bimaturism can refer to developmental differences within a sex related to secondary sex characteristics. For example, male orangutans reach sexual maturity around age 15 but undergo an additional period of development later in life before they exhibit cheek flanges. Flanged males are generally preferred by females so that unflanged males need different mating strategies to c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, or behavioural or cognitive traits. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', which is when both biological sexes are phenotypically indistinguishable from each other. Overview Ornamentation and coloration Common and easily identified types of dimorphism consist of ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is called sexual dichromatism, which is commonly seen in many species of birds and reptiles. Sexual selection leads to the exaggerat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simian
The simians, anthropoids, or higher primates are an infraorder (Simiiformes ) of primates containing all animals traditionally called monkeys and apes. More precisely, they consist of the parvorders New World monkeys (Platyrrhini) and Catarrhini, the latter of which consists of the superfamilies Cercopithecidae ( Old World monkeys in the stricter sense) and apes ( Hominoidea; including the genus ''Homo''). The simians are sister group to the tarsiers (Tarsiiformes), together forming the haplorhines. The radiation occurred about 60 million years ago (during the Cenozoic era); 40 million years ago, simians colonized South America, giving rise to the New World monkeys. The remaining simians (catarrhines) split about 25 million years ago into Cercopithecidae and apes (including humans). Taxonomy and evolution In earlier classification, New World monkeys, Old World monkeys, apes, and humans – collectively known as simians or anthropoids – were grouped under Anthropoid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gorillas
Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or five subspecies. The DNA of gorillas is highly similar to that of humans, from 95 to 99% depending on what is included, and they are the next closest living relatives to humans after chimpanzees and bonobos. Gorillas are the largest living primates, reaching heights between 1.25 and 1.8 metres, weights between 100 and 270 kg, and arm spans up to 2.6 metres, depending on species and sex. They tend to live in troops, with the leader being called a silverback. The Eastern gorilla is distinguished from the Western by darker fur colour and some other minor morphological differences. Gorillas tend to live 35–40 years in the wild. The oldest gorilla known is Fatou (b. 1957), who is still alive at the advanced age of 65 years. Gorillas' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Sex Characteristics
Secondary sex characteristics are features that appear during puberty in humans, and at sexual maturity in other animals. These characteristics are particularly evident in the sexually dimorphic phenotypic traits that distinguish the sexes of a species, but unlike the sex organs (primary sex characteristics), are not directly part of the reproductive system. Secondary sex characteristics are believed to be the product of sexual selection for traits which display fitness, giving an organism an advantage over its rivals in courtship and in aggressive interactions. Secondary sex characteristics include, for example, the manes of male lions, the bright facial and rump coloration of male mandrills, and horns in many goats and antelopes. These characteristics are believed to be produced by a positive feedback loop known as the Fisherian runaway produced by the secondary characteristic in one sex and the desire for that characteristic in the other sex. Male birds and fish of many spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orangutans
Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus ''Pongo'', orangutans were originally considered to be one species. From 1996, they were divided into two species: the Bornean orangutan (''P. pygmaeus'', with three subspecies) and the Sumatran orangutan (''P. abelii''). A third species, the Tapanuli orangutan (''P. tapanuliensis''), was identified definitively in 2017. The orangutans are the only surviving species of the subfamily Ponginae, which diverged genetically from the other hominids (gorillas, chimpanzees, and humans) between 19.3 and 15.7 million years ago. The most arboreal of the great apes, orangutans spend most of their time in trees. They have proportionally long arms and short legs, and have reddish-brown hair covering their bodies. Adult males weigh about , while fema ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Puberty
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a boy. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Before puberty, the external sex organs, known as primary sexual characteristics, are sex characteristics that distinguish boys and girls. Puberty leads to sexual dimorphism through the development of the secondary sex characteristics, which further distinguish the sexes. On average, girls begin puberty at ages 10–11 and complete puberty at ages 15–17; boys generally begin puberty at ages 11–12 and c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polygynous
Polygyny (; from Neoclassical Greek πολυγυνία (); ) is the most common and accepted form of polygamy around the world, entailing the marriage of a man with several women. Incidence Polygyny is more widespread in Africa than in any other continent. Some scholars see the slave trade's impact on the male-to-female sex ratio as a key factor in the emergence and fortification of polygynous practices in regions of Africa. Polygyny is most common in a region known as the "polygamy belt" in West Africa and Central Africa, with the countries estimated to have the highest polygamy prevalence in the world being Burkina Faso, Mali, Gambia, Niger and Nigeria. In the region of sub-Saharan Africa, polygyny is common and deeply rooted in the culture, with 11% of the population of sub-Saharan Africa living in such marriages (25% of the Muslim population and 3% of the Christian population, as of 2019). Polygyny is especially widespread in West Africa, with the countries estimated to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_(white_background)_(1).jpg "Click for more on -> Simian")
