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Stotting
Stotting (also called pronking or pronging) is a behavior of quadrupeds, particularly gazelles, in which they spring into the air, lifting all four feet off the ground simultaneously. Usually, the legs are held in a relatively stiff position. Many explanations of stotting have been proposed, though for several of them there is little evidence either for or against. The question of why prey animals stot has been investigated by evolutionary biologists including John Maynard Smith, C. D. Fitzgibbon, and Tim Caro; all of them conclude that the most likely explanation given the available evidence is that it is an honest signal to predators that the stotting animal would be difficult to catch. Such a signal is called "honest" as it is not deceptive in any way, and would benefit both predator and prey; the predator as it avoids a costly and unproductive chase, and the prey as it does not get chased. Etymology ''Stot'' is a common Scots and Northern English verb meaning "bounce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Handicap Principle
The handicap principle is a hypothesis proposed by the biologist Amotz Zahavi to explain how evolution may lead to "honest" or reliable signalling between animals which have an obvious motivation to bluff or deceive each other. It suggests that costly signals must be reliable signals, costing the signaller something that could not be afforded by an individual with less of a particular trait. For example, in sexual selection, the theory suggests that animals of greater biological fitness signal this status through handicapping behaviour, or morphology that effectively lowers this quality. The central idea is that sexually selected traits function like conspicuous consumption, signalling the ability to afford to squander a resource. Receivers then know that the signal indicates quality, because inferior-quality signallers are unable to produce such wastefully extravagant signals. History The handicap principle was proposed in 1975 by Israeli biologist Amotz Zahavi. The generali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antipredator Adaptation
Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avoiding detection, warding off attack, fighting back, or escaping when caught. The first line of defence consists in avoiding detection, through mechanisms such as camouflage, masquerade, apostatic selection, living underground, or nocturnality. Alternatively, prey animals may ward off attack, whether by advertising the presence of strong defences in aposematism, by mimicking animals which do possess such defences, by startling the attacker, by signalling to the predator that pursuit is not worthwhile, by distraction, by using defensive structures such as spines, and by living in a group. Members of groups are at reduced risk of predation, despite the increased conspicuousness of a group, through improved vigilance, predator confusio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Springbok Pronk
The springbok (''Antidorcas marsupialis'') is a medium-sized antelope found mainly in south and southwest Africa. The sole member of the genus ''Antidorcas'', this bovid was first described by the German zoologist Eberhard August Wilhelm von Zimmermann in 1780. Three subspecies are identified. A slender, long-legged antelope, the springbok reaches at the shoulder and weighs between . Both sexes have a pair of black, long horns that curve backwards. The springbok is characterised by a white face, a dark stripe running from the eyes to the mouth, a light-brown coat marked by a reddish-brown stripe that runs from the upper fore leg to the buttocks across the flanks like the Thomson's gazelle, and a white rump flap. Active mainly at dawn and dusk, springbok form harems (mixed-sex herds). In earlier times, springbok of the Kalahari desert and Karoo migrated in large numbers across the countryside, a practice known as ''trekbokking''. A feature, peculiar but not unique, to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Selfish Gene
''The Selfish Gene'' is a 1976 book on evolution by the ethologist Richard Dawkins, in which the author builds upon the principal theory of George C. Williams's '' Adaptation and Natural Selection'' (1966). Dawkins uses the term "selfish gene" as a way of expressing the gene-centred view of evolution (as opposed to the views focused on the organism and the group), popularising ideas developed during the 1960s by W. D. Hamilton and others. From the gene-centred view, it follows that the more two individuals are genetically related, the more sense (at the level of the genes) it makes for them to behave cooperatively with each other. A lineage is expected to evolve to maximise its inclusive fitness—the number of copies of its genes passed on globally (rather than by a particular individual). As a result, populations will tend towards an evolutionarily stable strategy. The book also introduces the term ''meme'' for a unit of human cultural evolution analogous to the gene, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mule Deer
The mule deer (''Odocoileus hemionus'') is a deer indigenous to western North America; it is named for its ears, which are large like those of the mule. Two subspecies of mule deer are grouped into the black-tailed deer. Unlike the related white-tailed deer (''Odocoileus virginianus''), which is found throughout most of North America east of the Rocky Mountains and in the valleys of the Rocky Mountains from Idaho and Wyoming northward, mule deer are only found on the western Great Plains, in the Rocky Mountains, in the southwest United States, and on the west coast of North America. Mule deer have also been introduced to Argentina and Kauai, Hawaii. Taxonomy Mule deer can be divided into two main groups: the mule deer (''sensu stricto'') and the black-tailed deer. The first group includes all subspecies, except ''O. h. columbianus'' and '' O. h. sitkensis'', which are in the black-tailed deer group. The two main groups have been treated as separate species, but they hybridiz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Springbok
The springbok (''Antidorcas marsupialis'') is a medium-sized antelope found mainly in south and southwest Africa. The sole member of the genus ''Antidorcas'', this bovid was first described by the German zoologist Eberhard August Wilhelm von Zimmermann in 1780. Three subspecies are identified. A slender, long-legged antelope, the springbok reaches at the shoulder and weighs between . Both sexes have a pair of black, long horns that curve backwards. The springbok is characterised by a white face, a dark stripe running from the eyes to the mouth, a light-brown coat marked by a reddish-brown stripe that runs from the upper fore leg to the buttocks across the flanks like the Thomson's gazelle, and a white rump flap. Active mainly at dawn and dusk, springbok form harems (mixed-sex herds). In earlier times, springbok of the Kalahari desert and Karoo migrated in large numbers across the countryside, a practice known as ''trekbokking''. A feature, peculiar but not unique ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomson's Gazelle
Thomson's gazelle (''Eudorcas thomsonii'') is one of the best known species of gazelles. It is named after explorer Joseph Thomson and is sometimes referred to as a "tommie". It is considered by some to be a subspecies of the red-fronted gazelle and was formerly considered a member of the genus ''Gazella'' within the subgenus ''Eudorcas'', before ''Eudorcas'' was elevated to genus status. Thomson's gazelles can be found in numbers exceeding 200,000 in Africa and are recognized as the most common type of gazelle in East Africa. A small fast antelope, the Thomson's gazelle is claimed to have top speeds up to . It is the fourth-fastest land animal, after the cheetah (its main predator), pronghorn, and springbok. Taxonomy and etymology The current scientific name of Thomson's gazelle is ''Eudorcas thomsonii''. It is a member of the genus '' Eudorcas'' and is classified under the family Bovidae. Thomson's gazelle was first described by British zoologist Albert Günther in 1884. ... [...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 when organisms with conflicting interests, such as in sexual selection, should be expected to provide honest signals (no presumption being made of conscious intention) rather than cheating. 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 might briefly benefit that signaller, at the risk of undermining the signalling system for the whole population. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Honest Signal
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 when organisms with conflicting interests, such as in sexual selection, should be expected to provide honest signals (no presumption being made of conscious intention) rather than cheating. 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 might briefly benefit that signaller, at the risk of undermining the signalling system for the whole population. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gazelle
A gazelle is one of many antelope species in the genus ''Gazella'' . This article also deals with the seven species included in two further genera, '' Eudorcas'' and '' Nanger'', which were formerly considered subgenera of ''Gazella''. A third former subgenus, '' Procapra'', includes three living species of Asian gazelles. Gazelles are known as swift animals. Some are able to run at bursts as high as or run at a sustained speed of . Gazelles are found mostly in the deserts, grasslands, and savannas of Africa; but they are also found in southwest and central Asia and the Indian subcontinent. They tend to live in herds, and eat fine, easily digestible plants and leaves. Gazelles are relatively small antelopes, most standing high at the shoulder, and are generally fawn-colored. The gazelle genera are ''Gazella'', ''Eudorcas'', and ''Nanger''. The taxonomy of these genera is confused, and the classification of species and subspecies has been an unsettled issue. Currently, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amotz Zahavi
Amotz Zahavi ( he, אמוץ זהבי) (August 14, 1928 – May 12, 2017) was an Israeli evolutionary biologist, a Professor in the Department of Zoology at Tel Aviv University, and one of the founders of the Society for the Protection of Nature in Israel. His main work concerned the evolution of signals, particularly those signals that are indicative of fitness, and their selection for "honesty". Biography Amotz Zahavi was influenced to study zoology by the director of the zoo at Tel Aviv, Heinrich Mendelssohn. He received his Ph.D. from Tel Aviv University in 1970. He was married to Avishag Zahavi, a biologist and a co-investigator. He died in Tel Aviv, Israel on May 12, 2017, aged 88. Scientific career Zahavi is best known for his work on the handicap principle, which explains the evolution of characteristics, behaviors or structures that appear contrary to the principles of Darwinian evolution in that they appear to reduce fitness and endanger individual organisms. Evolved ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheetah
The cheetah (''Acinonyx jubatus'') is a large cat native to Africa and central Iran. It is the fastest land animal, estimated to be capable of running at with the fastest reliably recorded speeds being , and as such has evolved specialized adaptations for speed, including a light build, long thin legs and a long tail. It typically reaches at the shoulder, and the head-and-body length is between . Adults weigh between . Its head is small and rounded, with a short snout and black tear-like facial streaks. The coat is typically tawny to creamy white or pale buff and is mostly covered with evenly spaced, solid black spots. Four subspecies are recognised. The cheetah lives in three main social groups: females and their cubs, male "coalitions", and solitary males. While females lead a nomadic life searching for prey in large home ranges, males are more sedentary and instead establish much smaller territories in areas with plentiful prey and access to females. The cheetah is acti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_in_the_road.jpg "Click for more on -> Springbok Pronk")
_Gazella_isabella_(white_background).png "Click for more on -> Thomson's Gazelle")
