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Sexual Ornament
A biological ornament is a characteristic of an animal that appears to serve a decorative function rather than a utilitarian function. Many are secondary sexual characteristics, and others appear on young birds during the period when they are dependent on being fed by their parents. Ornaments are used in displays to attract mates, which may lead to the evolutionary process known as sexual selection. An animal may shake, lengthen, or spread out its ornament in order to get the attention of the opposite sex, which will in turn choose the most attractive one with which to mate. Ornaments are most often observed in males, and choosing an extravagantly ornamented male benefits females as the genes that produce the ornament will be passed on to her offspring, increasing their own reproductive fitness. As Ronald Fisher noted, the male offspring will inherit the ornament while the female offspring will inherit the preference for said ornament, which can lead to a positive feedback loop kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Sexual Characteristic
A secondary sex characteristic is a physical characteristic of an organism that is related to or derived from its sex, but not directly part of its reproductive system. In humans, these characteristics typically start to appear during puberty—and include enlarged breasts and widened hips of females, facial hair and Adam's apples on males, and pubic hair on both. In non-human animals, they can start to appear at sexual maturity—and include, for example, the manes of male lions, the bright facial and rump coloration of male mandrills, and horns in many goats and antelopes. Secondary sex characteristics are particularly evident in the sexual dimorphism, sexually dimorphic phenotypic traits that distinguish the sexes of a species. In evolution, secondary sex characteristics are the product of sexual selection for traits that show fitness (biology), fitness, giving an organism an advantage over its rivals in courtship and in aggression, aggressive interactions. Many characteri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signalling Theory
Within evolutionary biology, signalling theory is a body of theoretical work examining communication between individuals, both within species and across species. The central question is how organisms with conflicting interests, such as in sexual selection, are expected to provide honest signals rather than deceive or cheat, given that the passing on of pleiotropic traits is subject to natural selection, which aims to minimize associated costs without assuming any conscious intent. Mathematical models describe how signalling can contribute to an evolutionarily stable strategy. Signals are given in contexts such as mate selection by females, which subjects the advertising males' signals to selective pressure. Signals thus evolve because they modify the behaviour of the receiver to benefit the signaller. Signals may be honest, conveying information which usefully increases the fitness of the receiver, or dishonest. An individual can cheat by giving a dishonest signal, which m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orb-weaver Spider
Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name of the group. Araneids have eight similar eyes, hairy or spiny legs, and no stridulating organs. The family has a cosmopolitan distribution, including many well-known large or brightly colored garden spiders. With 3,108 species in 186 genera worldwide, the Araneidae comprise one of the largest family of spiders (with the Salticidae and Linyphiidae). Araneid webs are constructed in a stereotypical fashion, where a framework of nonsticky silk is built up before the spider adds a final spiral of silk covered in sticky droplets. Orb webs are also produced by members of other spider families. The long-jawed orb weavers ( Tetragnathidae) were formerly included in the Araneidae; they are closely related, being part of the superfamily Araneo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Deer Stag 2009 Denmark
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–750 nanometres. It is a primary color in the RGB color model and a secondary color (made from magenta and yellow) in the CMYK color model, and is the complementary color of cyan. Reds range from the brilliant yellow-tinged scarlet and vermillion to bluish-red crimson, and vary in shade from the pale red pink to the dark red burgundy. Red pigment made from ochre was one of the first colors used in prehistoric art. The Ancient Egyptians and Mayans colored their faces red in ceremonies; Roman generals had their bodies colored red to celebrate victories. It was also an important color in China, where it was used to color early pottery and later the gates and walls of palaces. In the Renaissance, the brilliant red costumes for the nobility and wealthy were dyed with kermes and cochineal. The 19th century brought th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lek Mating
A lek is an aggregation of male animals gathered to engage in competitive displays and courtship rituals, known as lekking, to entice visiting females which are surveying prospective partners with which to mate. It can also refer to a space used by displaying males to defend their own share of territory for the breeding season. A lekking species is characterised by male displays, strong female mate choice, and the conferring of indirect benefits to males and reduced costs to females. Although most prevalent among birds such as black grouse, lekking is also found in a wide range of vertebrates including some bony fish, amphibians, reptiles, mammals, and arthropods including crustaceans and insects. A classical lek consists of male territories in visual and auditory range of each other. An exploded lek, as seen in the kākāpō (the owl parrot), has more widely separated territories, but still in auditory range. Lekking is associated with an apparent paradox: strong sexual s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuptial Tubercles
Nuptial tubercles or breeding tubercles (also called pearl organs or nuptial efflorescence) are noticeable skin roughness or horny nodules that form on male fish during breeding. They are made of keratin, the same material as hair, hooves, and fingernails. Use and description These tubercles are dermal structures present in 15 families of fish belonging to 4 orders of Actinopterygii – Salmoniformes, Gonorhynchiformes, Cypriniformes and Perciformes are used in the courtship and reproduction process. They consist of partially or fully keratinised cells that form in certain regions, used to stimulate females during courtship. Their development is stimulated by hormones secreted by the pituitary and adrenal glands, and is induced shortly before the breeding season and discarded after. In some species, at least, there is a correlation between the level of androgens present in the endocrine system and the volume and complexity of tubercle growth. They normally form on the he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Roach
The roach, or rutilus roach (''Rutilus rutilus''), also known as the common roach, is a fresh- and brackish-water fish of the family Cyprinidae, native to most of Europe and western Asia. Fish called roach can be any species of the genera ''Rutilus'', '' Leucos'' and ''Hesperoleucus'', depending on locality. The plural of the term is also roach. Description The roach is a small fish, often reaching no more than about ; maximum length is . Its body has a bluish-silvery colour and becomes white at the belly. The fins are red. The number of scales along the lateral line is 39–48. The dorsal and anal fins have 12–14 rays. Young specimens have a slender build; older specimens acquire a higher and broader body shape. The roach can often be recognized by the big red spot in the iris above and beside the pupil. Colours of the eye and fins can be very pale, however, in some environments. In Central and Northern Europe, the common roach can most easily be confused with the common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long-tailed Widowbird
The long-tailed widowbird (''Euplectes progne'') is a species of bird in the weaver family Ploceidae.Mackworth-Praed, C.W., and C.H. Grant. (1960). ''Birds of Eastern and North Eastern Africa''. Longmans, Green and Co LTD.; London The species is found in Angola, Botswana, the Democratic Republic of the Congo, Kenya, Lesotho, South Africa, Eswatini, and Zambia.Hall, B. P. and R. E. Moreau. (1970). An atlas of speciation in African passerine birds. British Museum of Natural History, London. The long-tailed widowbird is a medium-sized bird and one of the most common in the territories it inhabits.Andersson, M. (1982). "Female choice selects for extreme tail length in a widowbird." ''Nature'', 299: 818–820. Adult breeding males are almost entirely black with orange and white shoulders ("epaulets"), long, wide tails, and a bluish white bill. Females are rather inconspicuous, their feathers streaked tawny and black with pale patches on the chest, breast and back, narrow tail feathers, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lek (biology)
A lek is an aggregation of male animals gathered to engage in competitive displays and courtship rituals, known as lekking, to entice visiting females which are surveying prospective partners with which to mate. It can also refer to a space used by displaying males to defend their own share of territory for the breeding season. A lekking species is characterised by male displays, strong female mate choice, and the conferring of indirect benefits to males and reduced costs to females. Although most prevalent among birds such as black grouse, lekking is also found in a wide range of vertebrates including some teleost, bony fish, amphibians, reptiles, mammals, and arthropods including crustaceans and insects. A classical lek consists of male territories in visual and auditory range of each other. An exploded lek, as seen in the kākāpō (the owl parrot), has more widely separated territories, but still in auditory range. Lekking is associated with an apparent lek paradox, paradox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Widowbird
''Euplectes'' is a genus of passerine bird in the weaver family, Ploceidae, that contains the bishops and widowbirds. They are all native to Africa south of the Sahara. It is believed that all birds in the genus are probably polygynous. The genus ''Euplectes'' was introduced by the English naturalist William Swainson in 1829 with the southern red bishop as the type species. The name combines the Ancient Greek ''eu'' meaning "fine" or "good" with the Neo-Latin ''plectes'' meaning "weaver". When choosing their mates, females within this genus will often choose males with longer tail lengths, even in species with comparatively shorter tail lengths. Species The genus contains 18 species. Aviculture The yellow-crowned bishop and northern red bishop are popular in aviculture Aviculture is the practice of keeping and breeding birds, especially of wild birds in captivity. Aviculture Aviculture is the practice of keeping birds (class '' Aves'') in captivity in controlled conditi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blausteinsee Tierwelt 03
The Blausteinsee Leisure and Recreation Area is an artificial lake north of the Eschweiler municipality in the Aachen district of North Rhine-Westphalia, Germany. Its area is around 100 hectares and depth is 46m. It was created during the regeneration of the ''Zukunft'' opencast coal mine in the Rhineland coalfield, made by flooding the pit left by the mine with water. Today, the lake is a holiday area for the surrounding towns. The surface of the lake is 129 metres above sea level and its volume is around 25 million cubic metres. The filling of the lake began in 1994. The owner of the Blausteinsee is the Blausteinsee Leisure Centre GmbH, which was founded as a support organization in 1982 by the municipalities of Aldenhoven, Alsdorf, Eschweiler, Stolberg and Würselen. The aim of this company is to create and maintain an attractive leisure and recreational area for the people of the Aachen region, along with coordination of activities on and around the lake. Location and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible Signs and symptoms of cancer, signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in defecation, bowel movements. While these symptoms may indicate cancer, they can also have other causes. List of cancer types, Over 100 types of cancers affect humans. Tobacco use is the cause of about 22% of cancer deaths. Another 10% are due to obesity, poor Diet (nutrition), diet, sedentary lifestyle, lack of physical activity or Alcohol abuse, excessive alcohol consumption. Other factors include certain infections, exposure to ionizing radiation, and environmental pollutants. infectious causes of cancer, Infection with specific viruses, bacteria and parasites is an environmental factor cau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
