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Ruth Geyer Shaw
Ruth Geyer Shaw (born 1953) is a professor and principal investigator in the Department of Ecology, Evolution and Behavior at the University of Minnesota. She studies the processes involved in genetic variation, specializing in plant population biology and evolutionary quantitative genetics. Her work is particularly relevant in studying the effects of stressors such as climate instability and population fragmentation on evolutionary change in populations. She has developed and applied new statistical methods for her field and is considered a leading population geneticist. Shaw has been active on a number of editorial boards, most recently as chief editor of the journal ''Evolution'' (2013–2017). She has received several awards including the 2017 Sewall Wright Award from the American Society of Naturalists, given to a senior investigator who continues to make fundamental contributions to "the conceptual unification of the biological sciences". Early life Shaw's parent wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionary Biology
Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life forms on Earth. Evolution is based on the theory that all species are related and they gradually change over time. In a population, the genetic variations affect the physical characteristics i.e. phenotypes of an organism. These changes in the phenotypes will be an advantage to some organisms, which will then be passed onto their offspring. Some examples of evolution in species over many generations are the Peppered Moth and Flightless birds. In the 1930s, the discipline of evolutionary biology emerged through what Julian Huxley called the modern synthesis of understanding, from previously unrelated fields of biological research, such as genetics and ecology, systematics, and paleontology. The importance of studying Evolutionary biology is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Washington
The University of Washington (UW, simply Washington, or informally U-Dub) is a public research university in Seattle, Washington. Founded in 1861, Washington is one of the oldest universities on the West Coast; it was established in Seattle approximately a decade after the city's founding. The university has a 703 acre main campus located in the city's University District, as well as campuses in Tacoma and Bothell. Overall, UW encompasses over 500 buildings and over 20 million gross square footage of space, including one of the largest library systems in the world with more than 26 university libraries, art centers, museums, laboratories, lecture halls, and stadiums. The university offers degrees through 140 departments, and functions on a quarter system. Washington is the flagship institution of the six public universities in Washington state. It is known for its medical, engineering, and scientific research. Washington is a member of the Association of American Universiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Margaret Bryan Davis
Dr. Margaret Bryan Davis (''née'' Margaret Bryan; born October 23, 1931) is an American palynologist and paleoecologist, who used pollen data to study the vegetation history of the past 21,000 years (i.e. since the last ice age). She showed conclusively that temperate- and boreal-forest species migrated at different rates and in different directions while forming a changing mosaic of communities. Early in her career, she challenged the standard methods and prevailing interpretations of the data and fostered rigorous analysis in palynology. As a leading figure in ecology and paleoecology, she served as president of the Ecological Society of America and the American Quaternary Association and as chair of the Department of Ecology, Evolution and Behavior at the University of Minnesota. In 1982 she was elected to the National Academy of Sciences and, in 1993, received the Eminent Ecologist Award from the Ecological Society of America. Early life and education Davis was born on October ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inbreeding
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious or recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid incest only rarely. Inbreeding results in homozygosity, which can increase the chances of offspring being affected by recessive traits. In extreme cases, this usually leads to at least temporarily decreased biological fitness of a population (called inbreeding depression), which is its ability to survive and reproduce. An individual who inherits such deleterious traits is colloquially referred to as ''inbred''. The avoidance of expression of such deleterious recessive alleles caused by inbreeding, via inbreeding avoidance mechanisms, is the main selective reason for outcrossin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinacea Angustifolia
''Echinacea angustifolia'', the narrow-leaved purple coneflower or blacksamson echinacea, is a species of flowering plant in the family Asteraceae. It is native to North America, where it is widespread across much of the Great Plains of central Canada and the central United States, with additional populations in surrounding regions. ''E. angustifolia'' is a perennial herb with spindle-shaped taproots that are often branched. The stems and leaves are moderately to densely hairy. The plant produces one flower heads one branch - each at the end of a long peduncle. Each flower head contains 8–21 pink or purple ray florets plus 80–250 orange disc florets. ''Echinacea angustifolia'' blooms in late spring to mid-summer. It is found growing in dry prairies and barrens with rocky to sandy-clay soils. There are two subspecies: *''Echinacea angustifolia subsp. angustifolia'' is native to central Canada and the central United States from Saskatchewan and Manitoba in the north to Arizo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Experiments
Field experiments are experiments carried out outside of laboratory settings. They randomly assign subjects (or other sampling units) to either treatment or control groups in order to test claims of causal relationships. Random assignment helps establish the comparability of the treatment and control group, so that any differences between them that emerge after the treatment has been administered plausibly reflect the influence of the treatment rather than pre-existing differences between the groups. The distinguishing characteristics of field experiments are that they are conducted real-world settings and often unobtrusively. This is in contrast to laboratory experiments, which enforce scientific control by testing a hypothesis in the artificial and highly controlled setting of a laboratory. Field experiments have some contextual differences as well from naturally-occurring experiments and quasi-experiments. While naturally-occurring experiments rely on an external force (e.g. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Darwin (unit)
The darwin (d) is a unit of evolutionary change, defined by J. B. S. Haldane in 1949.J.B.S. Haldane (1949).Suggestions as to quantitative measurement of rates of evolution" ''Evolution'' 3:51–56. One darwin is defined to be an e-fold (about 2.718) change in a trait over one million years. Haldane named the unit after Charles Darwin. Equation The equation for calculating evolutionary change in darwins (r) is: :r=\frac where X_1 and X_2 are the initial and final values of the trait and \Delta t is the change in time in millions of years. An alternative form of this equation is: :r=\frac Since the difference between two natural logarithms is a dimensionless ratio, the trait may be measured in any unit. Inexplicably, Haldane defined the millidarwin as 10−9 darwins, despite the fact that the prefix milli- usually denotes a factor of one thousandth (10−3). Application The measure is most useful in palaeontology, where macroevolutionary changes in the dimensions of fossils c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guppy
The guppy (), also known as millionfish and rainbow fish, is one of the world's most widely distributed tropical fish and one of the most popular freshwater aquarium fish species. It is a member of the family Poeciliidae and, like almost all American members of the family, is live-bearing. Guppies originate from northeast South America, but have been introduced to many environments and are now found all over the world. They are highly adaptable and thrive in many different environmental and ecological conditions. Male guppies, which are smaller than females, have ornamental caudal and dorsal fins. Wild guppies generally feed on a variety of food sources, including benthic algae and aquatic insect larvae. Guppies are used as a model organism in the fields of ecology, evolution, and behavioural studies. Taxonomy Guppies were first described in Venezuela as ''Poecilia reticulata'' by Wilhelm Peters in 1859 and as ''Lebistes poecilioides'' in Barbados by De Filippi in 1861. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Experimental Evolution
Experimental evolution is the use of laboratory experiments or controlled field manipulations to explore evolutionary dynamics. Evolution may be observed in the laboratory as individuals/populations adapt to new environmental conditions by natural selection. There are two different ways in which adaptation can arise in experimental evolution. One is via an individual organism gaining a novel beneficial mutation. The other is from allele frequency change in standing genetic variation already present in a population of organisms. Other evolutionary forces outside of mutation and natural selection can also play a role or be incorporated into experimental evolution studies, such as genetic drift and gene flow. The organism used is decided by the experimenter, based on the hypothesis to be tested. Many generations are required for adaptive mutation to occur, and experimental evolution via mutation is carried out in viruses or unicellular organisms with rapid generation times, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predator Fish
Predatory fish are hypercarnivorous fish that actively prey upon other fish or aquatic animals, with examples including shark, billfish, barracuda, pike/muskellunge, walleye, perch and salmon. Some omnivorous fish, such as the red-bellied piranha, can occasionally also be predatory, although they are not strictly regarded as obligately predatory fish. Populations of large predatory fish in the global oceans were estimated to be about 10% of their pre-industrial levels by 2003, and they are most at risk of extinction; there was a disproportionate level of large predatory fish extinctions during the Cretaceous–Paleogene extinction event 66 million years ago. Creation of marine reserves has been found to restore populations of large predatory fish such as the ''Serranidae'' — groupers and sea bass. Predatory fish switch between types of prey in response to variations in their abundance. Such changes in preference are disproportionate and are selected for as evolutionarily ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David N
David (; , "beloved one") (traditional spelling), , ''Dāwūd''; grc-koi, Δαυΐδ, Dauíd; la, Davidus, David; gez , ዳዊት, ''Dawit''; xcl, Դաւիթ, ''Dawitʿ''; cu, Давíдъ, ''Davidŭ''; possibly meaning "beloved one". was, according to the Hebrew Bible, the Kings of Israel and Judah, third king of the Kingdom of Israel (united monarchy), United Kingdom of Israel. In the Books of Samuel, he is described as a young shepherd and Lyre, harpist who gains fame by slaying Goliath, a champion of the Philistines, in southern Canaan. David becomes a favourite of Saul, the first king of Israel; he also forges David and Jonathan, a notably close friendship with Jonathan (1 Samuel), Jonathan, a son of Saul. However, under the paranoia that David is seeking to usurp the throne, Saul attempts to kill David, forcing the latter to go into hiding and effectively operate as a fugitive for several years. After Saul and Jonathan are both killed in battle against the Philistin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
