|
Jordan's Rule
Jordan's rule (sense 1) is an ecogeographical rule that describes the inverse relationship between water temperature and meristic characteristics in various species of fish. The most commonly observed relationship is that fin ray, vertebrae, or scale numbers increase with decreasing temperature. The rule is named after David Starr Jordan (1851–1931), the father of American ichthyology. Jordan's law (or rule) (sense 2) is also an ecogeographical rule (named after the same scientist) that states: "‘ ven any species in any region, the nearest related species is not likely to be found in the same region nor in a remote region, but in a neighbouring district separated from the first by a barrier of some sort’ This "rule" is frequently violated (see discussion in Fitzpatrick & Turelli 2007), but when patterns are consistent with Jordan's rule (sense 2), this suggests an important role for allopatric speciation in the diversification of the clade in question. Jordan himself wrote: "T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecogeographical Rule
A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms. Biological rules and laws are often developed as succinct, broadly applicable ways to explain complex phenomena or salient observations about the ecology and biogeographical distributions of plant and animal species around the world, though they have been proposed for or extended to all types of organisms. Many of these regularities of ecology and biogeography are named after the biologists who first described them. From the birth of their science, biologists have sought to explain apparent regularities in observational data. In his biology, Aristotle inferred rules governing differences between live-bearing tetrapods (in modern terms, terrestrial placental mammals). Among his rules were that brood size decreases with adult body mass, while lifespan increases with gestation period and with body mass, and fecundity decreases with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, the equivalent Latin term ''cladus'' (plural ''cladi'') is often used in taxonomical literature. The common ancestor may be an individual, a population, or a species (extinct or extant). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic. Some of the relationships between org ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jordan's Principle
Jordan's Principle is a child-first and needs-based principle used in public policy and administration in Canada to ensure that First Nations children living on and off reserve have equitable access to all government funded public services. It holds that First Nations children should not be denied access to public services while governments fight over who should pay. In order to ensure substantive equality, this can also include services that are not ordinarily available to other children. According to the First Nations Child & Family Caring Society of Canada, the organization that hosts the Jordan's Principle campaign: Jordan’s Principle ensures that First Nations children can access all public services when they need them. Services need to be culturally-based and take into full account the historical disadvantage linked to colonization that many First Nations children live with. The government of first contact pays for the service and resolves jurisdictional/payment disputes l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bergmann's Rule
Bergmann's rule is an ecogeographical rule that states that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, while populations and species of smaller size are found in warmer regions. Bergmann's rule only describes the overall size of the animals, but does not include body parts like Allen's rule does. Although originally formulated in relation to species within a genus, it has often been recast in relation to populations within a species. It is also often cast in relation to latitude. It is possible that the rule also applies to some plants, such as ''Rapicactus''. The rule is named after nineteenth century German biologist Carl Bergmann, who described the pattern in 1847, although he was not the first to notice it. Bergmann's rule is most often applied to mammals and birds which are endotherms, but some researchers have also found evidence for the rule in studies of ectothermic species, such as the ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allopatric Speciation
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodies of water, or glaciers. Human activity such as agriculture or developments can also change the distribution of species populations. These factors can substantially alter a region's geography, resulting in the separation of a species population into isolated subpopulations. The vicariant populations then undergo genetic changes as they become subjected to different selective pressures, experience genetic drift, and accumulate different mutations in the separated populations' gene pools. The barriers prevent the exchange of genetic information between th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allen's Rule
Allen's rule is an ecogeographical rule formulated by Joel Asaph Allen in 1877, broadly stating that animals adapted to cold climates have thicker limbs and bodily appendages than animals adapted to warm climates. More specifically, it states that the body surface-area-to-volume ratio for homeothermic animals varies with the average temperature of the habitat to which they are adapted (i.e. the ratio is low in cold climates and high in hot climates). Explanation Allen's rule predicts that endothermic animals with the same body volume should have different surface areas that will either aid or impede their heat dissipation. Because animals living in cold climates need to conserve as much heat as possible, Allen's rule predicts that they should have evolved comparatively low surface area-to-volume ratios to minimize the surface area by which they dissipate heat, allowing them to retain more heat. For animals living in warm climates, Allen's rule predicts the opposite: that they s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stigler's Law Of Eponymy
Stigler's law of eponymy, proposed by University of Chicago statistics professor Stephen Stigler in his 1980 publication ''Stigler’s law of eponymy'', states that no scientific discovery is named after its original discoverer. Examples include Hubble's law, which was derived by Georges Lemaître two years before Edwin Hubble, the Pythagorean theorem, which was known to Babylonian mathematicians before Pythagoras, and Halley's Comet, which was observed by astronomers since at least 240 BC (although its official designation is due to the first ever mathematical prediction of such astronomical phenomenon in the sky, not to its discovery). Stigler himself named the sociologist Robert K. Merton as the discoverer of "Stigler's law" to show that it follows its own decree, though the phenomenon had previously been noted by others. Derivation Historical acclaim for discoveries is often assigned to persons of note who bring attention to an idea that is not yet widely known, whethe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moritz Wagner (naturalist)
Moritz Wagner ( Bayreuth, 3 October 1813 – Munich, 31 May 1887) was a German explorer, collector, geographer and natural historian. Wagner devoted three years (1836–1839) to the exploration of Algiers: it was here that he made important observations in natural history, which he later supplemented and developed: that geographical isolation could play a key role in speciation. From 1852 to 1855, together with Carl Scherzer, Wagner travelled through North and Central America and the Caribbean. In May 1843, Wagner toured the Lake Sevan region of Armenia with Armenian writer Khachatur Abovian. He committed suicide in Munich, aged 73. His brother Rudolf was a physiologist and anatomist. Wagner's significance in evolutionary biology Wagner's early career was as a geographer, and he published a number of geographical books about North Africa, the Middle East, and Tropical America. He was also a keen naturalist and collector, and it is for this work he is best known among biologis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joel Asaph Allen
Joel Asaph Allen (July 19, 1838 – August 29, 1921) was an American zoologist, mammalogist, and ornithologist. He became the first president of the American Ornithologists' Union, the first curator of birds and mammals at the American Museum of Natural History, and the first head of that museum's Department of Ornithology. He is remembered for Allen's rule, which states that the bodies of endotherms (warm-blooded animals) vary in shape with climate, having increased surface area in hot climates to lose heat, and minimized surface area in cold climates, to conserve heat. Early life Allen was born in Springfield, Massachusetts, the son of Joel Allen and Harriet Trumbull. He studied and collected specimen of natural history early in life, but he was forced to sell his relatively large collection so that he could attend the Wilbraham & Monson Academy in 1861. The following year, he transferred to Harvard University, where he studied under Louis Agassiz. Career as a field collector o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allopatric Speciation
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodies of water, or glaciers. Human activity such as agriculture or developments can also change the distribution of species populations. These factors can substantially alter a region's geography, resulting in the separation of a species population into isolated subpopulations. The vicariant populations then undergo genetic changes as they become subjected to different selective pressures, experience genetic drift, and accumulate different mutations in the separated populations' gene pools. The barriers prevent the exchange of genetic information between th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Relationship
In statistics, there is a negative relationship or inverse relationship between two variables if higher values of one variable tend to be associated with lower values of the other. A negative relationship between two variables usually implies that the correlation between them is negative, or — what is in some contexts equivalent — that the slope in a corresponding graph is negative. A negative correlation between variables is also called anticorrelation or inverse correlation. Negative correlation can be seen geometrically when two normalized random vectors are viewed as points on a sphere, and the correlation between them is the cosine of the arc of separation of the points on the sphere. When this arc is more than a quarter-circle (θ > π/2), then the cosine is negative. Diametrically opposed points represent a correlation of –1 = cos(π). Any two points not in the same hemisphere have negative correlation. An example would be a negative cross-sectiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyology
Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish ( Agnatha). According to FishBase, 33,400 species of fish had been described as of October 2016, with approximately 250 new species described each year. Etymology The word is derived from the Greek words ἰχθύς, ''ikhthus'', meaning "fish"; and λογία, ''logia'', meaning "to study". History The study of fish dates from the Upper Paleolithic Revolution (with the advent of "high culture"). The science of ichthyology was developed in several interconnecting epochs, each with various significant advancements. The study of fish receives its origins from humans' desire to feed, clothe, and equip themselves with useful implements. According to Michael Barton, a prominent ichthyologist and professor at Centre College, "the earliest ichthyologists were '' hunters and gatherers'' who had learned how to obtain the most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
