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Neolamprologus Pulcher
''Neolamprologus pulcher'' is a species of cichlid endemic to Lake Tanganyika where it prefers locations with plenty of sedimentation. The common names for ''N. pulcher'' include daffodil cichlid, fairy cichlid, princess of Zambia and lyretail cichlid. This species can reach a length of TL. It can also be found in the aquarium trade. Taxonomy and phylogeny Previously, it was believed that ''N. pulcher'' and ''N. brichardi'' were two distinct species. Now they are considered the same species, the only difference being that Neolamprologus brichardi has a black stripe running from its eye to its gill cover and a yellow spot just above it, both of which are absent in N. pulcher. Because Neolamprologus pulcher is the older of the two scientific names, the rules of scientific nomenclature would make this the correct name for the species. The daffodil cichlid, when it was still known as N. brichardi, was named after Pierre Brichard, a Belgian who set up a collection station, for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethelwynn Trewavas
Ethelwynn Trewavas (5 November 1900 – 16 August 1993) was an ichthyologist at the British Museum of Natural History. She was known for her work on the families Cichlidae and Sciaenidae. She worked with Charles Tate Regan, another ichthyologist and taxonomist. Academic studies and career She received her bachelor's degree and Board of Education Certificate in Teaching in 1921 from Reading University, and then worked as a teacher before being employed by the King's College of Household and Social Science as a part-time demonstrator, spending most of her time on research. She was taught by Dr. Nellie B. Eales when associated with the Freshwater Biological Association. She met Charles Regan and was employed by him as his assistant until hired by the British Museum (Natural History) as Assistant Keeper in 1935. She was appointed Deputy Keeper of Zoology in 1958, and retired in 1961. She served as the senior scientist in the Fish Section of the British Museum (Natural Hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sperm Competition
Sperm competition is the competitive process between Spermatozoon, spermatozoa of two or more different males to fertility, fertilize the same Egg cell, egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and variety of mates increases a female's chance to produce more viable offspring. However, multiple mates for a female means each individual male has decreased chances of producing offspring. Sperm competition is an evolutionary pressure on males, and has led to the development of adaptations to increase male's chance of reproductive success. Sperm competition results in a sexual conflict between males and females. Males have evolved several defensive tactics including: mate-guarding, mating plugs, and releasing toxic seminal substances to reduce female re-mating tendencies to cope with sperm competition. Offensive tactics of sperm competition involve direct interference by one male on the reproductive succes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polygyny In Animals
Polygyny (; from Neo-Greek , ) is a mating system in which one male lives and mates with multiple females but each female only mates with a single male. Systems where several females mate with several males are defined either as promiscuity or polygynandry. Lek mating is frequently regarded as a form of polygyny, because one male mates with many females, but lek-based mating systems differ in that the male has no attachment to the females with whom he mates, and that mating females lack attachment to one another.Clutton-Brock T.H. (1989). ‘Review lecture: mammalian mating systems.' ''Proceedings of the Royal Society of London''. Series B, Biological Sciences 236: 339–372. Polygyny is typical of one-male, multi-female groupsBoyd, R., & Silk, J. B. (2009). How Humans Evolved (preferably the downloadable pdf version): WW Norton & Company, New York. and can be found in many species including: elephant seal, spotted hyena, gorilla, red-winged prinia, house wren, hamadryas bab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Androgens
An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the embryological development of the primary male sex organs, and the development of male secondary sex characteristics at puberty. Androgens are synthesized in the testes, the ovaries, and the adrenal glands. Androgens increase in both males and females during puberty. The major androgen in males is testosterone. Dihydrotestosterone (DHT) and androstenedione are of equal importance in male development. DHT ''in utero'' causes differentiation of the penis, scrotum and prostate. In adulthood, DHT contributes to balding, prostate growth, and sebaceous gland activity. Although androgens are commonly thought of only as male sex hormones, females also have them, but at lower levels: they function in libido and sexual arousal. Androgens are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterospecific
Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organisms or constituents of living organisms of being special or doing something special. Each animal or plant species is special. It differs in some way from all other species...biological specificity is the major problem about understanding life." Biological specificity within ''Homo sapiens'' ''Homo sapiens'' has many characteristics that show the biological specificity in the form of behavior and morphological traits. Morphologically, humans have an enlarged cranial capacity and more gracile features in comparison to other hominins. The reduction of dentition is a feature that allows for the advantage of adaptability in diet and survival. As a species, humans are culture dependent and much of human survival relies on the culture and socia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucocorticoid
Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebrate animal cell. The name "glucocorticoid" is a portmanteau of "glucose", "cortex", and "steroid" and is composed from its role in regulation of glucose metabolism, synthesis in the adrenal cortex, and its steroidal structure (see structure below). Glucocorticoids are part of the feedback mechanism in the immune system, which reduces certain aspects of immune function, such as inflammation. They are therefore used in medicine to treat diseases caused by an Autoimmunity, overactive immune system, such as Allergy, allergies, asthma, autoimmune diseases, and sepsis. Glucocorticoids have many Side effect, diverse effects such as pleiotropy (drugs), pleiotropy, including Adverse drug reaction, potentially harmful side effects. They also interfer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agonistic Behavior
Agonistic behaviour is any social behaviour related to fighting, which can include aggressive behaviour, but also threats, displays, retreats, placation, and conciliation. The term "agonistic behaviour" was first defined and used by J.P. Scott and Emil Fredericson in 1951 in their paper "The Causes of Fighting in Mice and Rats" in ''Physiological Zoology.'' Agonistic behaviour is seen in many animal species because resources including food, shelter, and mates are often limited. Some forms of agonistic behaviour are between contestants who are competing for access to the same resources, such as food or mates. Other times, it involves tests of strength or threat display that make animals look large and more physically fit, a display that may allow it to gain the resource before an actual battle takes place. Although agonistic behaviour varies among species, agonistic interaction consists of three kinds of behaviours: threat, aggression, and submission. These three behaviours ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Respirometer
A respirometer is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and/or carbon dioxide. They allow investigation into how factors such as age, or chemicals affect the rate of respiration. Respirometers are designed to measure respiration either on the level of a whole animal or plant or on the cellular level. These fields are covered by whole animal and cellular (or mitochondrial) respirometry, respectively. A simple whole plant respirometer designed to measure oxygen uptake or CO2 release consists of a sealed container with the living specimen together with a substance to absorb the carbon dioxide given off during respiration, such as soda lime pellets or cotton wads soaked with potassium hydroxide. The oxygen uptake is detected by manometry. Typically, a U-tube manometer is used, which directly shows the pressure difference between the container and the atmosphere. As an organism takes up O2, it generates a propo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Androgen
An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the embryological development of the primary male sex organs, and the development of male secondary sex characteristics at puberty. Androgens are synthesized in the testes, the ovaries, and the adrenal glands. Androgens increase in both males and females during puberty. The major androgen in males is testosterone. Dihydrotestosterone (DHT) and androstenedione are of equal importance in male development. DHT ''in utero'' causes differentiation of the penis, scrotum and prostate. In adulthood, DHT contributes to balding, prostate growth, and sebaceous gland activity. Although androgens are commonly thought of only as male Sex steroids, sex hormones, females also have them, but at lower levels: they function in libido and sexual arousal. An ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testosterone
Testosterone is the primary male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of androgenic hair, body hair. It is associated with increased aggression, sex drive, Dominance hierarchy, dominance, courtship display, and a wide range of behavioral characteristics. In addition, testosterone in both sexes is involved in health and well-being, where it has a significant effect on overall mood, cognition, social and sexual behavior, metabolism and energy output, the cardiovascular system, and in the prevention of osteoporosis. Insufficient levels of testosterone in men may lead to abnormalities including frailty, accumulation of adipose fat tissue within the body, anxiety and depression, sexual performance issues, and bone loss. Excessiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
