It follows that any systematic change in the frequency of alleles in a population "must" be due to the effect of one or more of these causes. Of course, like all aspects of Mendelian inheritance, the expected proportions of alleles are probabilities. It was for that reason that statistical tests of significance, such as standard errors, were developed.
Although all changes must be due to perturbations, not all perturbations lead to changes. The classic case is balancing selection, such as heterozygote advantage: "Heterosis: the heterozygote at a locus is fitter than either homozygote". Balancing selection leads to an equilibrium population with Hardy–Weinberg proportions
The law permits the prediction of genotype frequencies from a knowledge of gene frequencies.
Thus, equations can be written in terms of allele frequencies, and hypotheses about how phenotypes are inherited can be tested from population data.
G.H. Hardy
Geff Harold Hardy FRS (7 February 1877 Cranleigh, Surrey – 1 December 1947 Cambridge, Cambridgeshire) was a famous English mathematician. He investigated number theory and mathematical analysis.
Hardy's classic text "A course of pure mathematics" was first published in 1908 and has been in print ever since. He wrote "A Mathematician's Apology" in 1940.
In 1908, unable to explain how a dominant gene would not become ubiquitous in a population, Reginald Punnett introduced his problem to Hardy, with whom he played cricket. Hardy went on to formulate what became known as the Hardy–Weinberg law.
Hardy had a long collaboration with J.E. Littlewood, which resulted in a partial solution to a famous unsolved problem in number theory:
Hardy discovered the Indian mathematician Srinivasa Ramanujan, who was a brilliant student. Hardy saw his extraordinary intelligence and they worked together on many mathematical subjects. In an interview given to Paul Erdős, Hardy said that the discovery of Ramanujan was his (Hardy's) greatest contribution to mathematics and that their collaboration was "the one romantic incident in my life".
Sarcostemma clausum
White Vine ("Sarcostemma clausum") is a species of plant. It is also known as White Twinevine. It belongs in the subfamily Asclepiadoideae. It is native to southeastern United States and Texas.
Wilhelm Weinberg
Wilhelm Weinberg (1862 – 1937) was a German Jewish physician who became an important geneticist. He was a obstetrician and gynecologist, practising in Stuttgart. In 1908, he expressed the principle which would later come to be known as the Hardy–Weinberg law. Weinberg is also credited as the first to explain the effect of ascertainment bias on observations in genetics.
Weinberg was born in Stuttgart and studied medicine at Tübingen and Munich, receiving an M.D. in 1886. He returned to Stuttgart in 1889, where he remained running a large practice as a gynecologist and obstetrician until he retired to Tübingen a few years before his death in 1937. Much of his academic life was spent studying genetics, especially on applying the laws of inheritance in populations.
Weinberg developed the principle of genetic equilibrium independently of British mathematician G.H. Hardy. He delivered an exposition of his ideas in a lecture on 13 January 1908, about six months before Hardy's paper was published in English. His lecture was printed later that year in the society's yearbook.
Weinberg's contributions were unrecognized in the English speaking world for more than 35 years. Curt Stern, a German geneticist who emigrated to the United States before World War II, pointed out in a brief paper in "Science" that Weinberg's exposition was both earlier and more comprehensive than Hardy's.
Weinberg pioneered studies of twins, and developed techniques to analyse phenotypic variation. His aim was to partition this variance into genetic and environmental components. In the process, he recognized that ascertainment bias was affecting many of his calculations, and he produced methods to correct for it.
Weinberg observed that proportions of homozygotes in familial studies of classic recessive genetic diseases generally exceed the expected Mendelian ratio of 1:4, and he explained how this is the result of ascertainment bias. In his work with albino children, he recognized that in some families where both parents carry a recessive mutation, by chance no albino child occurs. He reasoned that many carrier couples were not being counted, and he demonstrated methods for correcting results to produce the expected Mendelian ratios.
He discovered the answer to several seeming paradoxes caused by ascertainment bias. For example, he explained that the reason that parents as a whole are more fertile than their children is because children must necessarily come from fertile parents.
By the same token, he recognized that ascertainment was responsible for a phenomenon known as "genetic anticipation", the tendency for a genetic disease to manifest earlier in life and with increased severity in later generations. Weinberg recognized that this was because those later generations were the offspring of that selected group of earlier carriers that had successfully reproduced.
Additional contributions by Weinberg to statistical genetics included the first estimate of the rate of twinning. Realizing that identical twins would have to be the same sex, while non-identical twins could be either same or opposite sex, Weinberg derived the formula for estimating the frequency of MZ and DZ twins from the ratio of same and opposite sex twins to the total of maternities. Weinberg also estimated that the heritability of twinning itself was close to zero.
Centre Georges-Vézina
The Centre Georges-Vézina, called the Colisée de Chicoutimi at first, is an arena in Chicoutimi, Quebec, Canada that has space for 4,651 pepple (including 3,683 seats). It where the Chicoutimi Saguenéens ice hockey team play. It is named for Georges Vézina, who played for the Montreal Canadiens as the goaltender and was from Chicoutimi. The arena was built in 1949 and has an ice surface of 200 feet by 100 feet, which is what the Olympics use.
Apocynum cannabinum
Apocynum cannabinum (commonly known as "Indian hemp") is a species of plant. It is also known as Dogbane, Amy Root, Hemp Dogbane, Rheumatism Root, and Wild Cotton. It is native to all of North America. It blooms from June to August. This species is found in moist lowlands, near stream edges, and near pond edges. It likes to grow in sandy or gravelly soil. Its height is 1–4 feet.
Indian hemp
Indian hemp can be any one of the following species of plants:
Wild Cotton
Wild Cotton can be one of two species of plants:
List of current NHL captains and alternate captains
The National Hockey League (NHL) is a professional ice hockey league with 31 teams founded in 1917. Each team can select a captain, who has the "sole privilege of discussing with the Referee any questions relating to interpretation of rules which may arise during the progress of a game". Each team is also allowed to pick alternate captains, who work when the captain is not on the ice. Captains have to wear the letter "C" on their uniform to show who they are; alternate captains wear the letter "A". Both letters are in height.
Some teams in the NHL do not have a captain. Rule 6.2 of the 2008–09 Official NHL Rulebook says that "[only] when the Captain is not in uniform, the Coach shall have the right to designate three Alternate Captains. This must be done prior to the start of the game." Many NHL teams with a captain select more than two alternate captains and change who wears the "A" for different games during the season.