"universal truths applicable to both microscopic and macroscopic organisms. The microorganisms in such endeavors consequently should be recognized as organisms rather than simply as molecular or evolutionary reductionist model systems. Thus, the study of RNA ""in vitro"" evolution is not microbial population biology and nor is the ""in silico"" generation of phylogenies of otherwise non-microbial sequences, even if aspects of either may in some (especially unintentional) manner be analogous to evolution in actual microbial populations. Microbial population biology can (and often does) involve the testing of more-general ecological and evolutionary hypotheses. Again, it is important to retain some emphasis on"
"gene. These changes in DNA sequence are called mutations. Mutations produce new alleles of genes. Sometimes these changes stop the functioning of that gene or make it serve another advantageous function, such as the melanin genes discussed above. These mutations and their effects on the traits of organisms are one of the causes of evolution. A population of organisms evolves when an inherited trait becomes more common or less common over time. For instance, all the mice living on an island would be a single population of mice: some with white fur, some gray. If over generations, white mice became"
"Evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes that are passed on from parent to offspring during reproduction. Different characteristics tend to exist within any given population as a result of mutation, genetic recombination and other sources of genetic variation. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or rare within a population. It is this process of evolution that has given rise to biodiversity at every level of"
"Gene flow In population genetics, gene flow (also known as gene migration or allele flow) is the transfer of genetic variation from one population to another. If the rate of gene flow is high enough, then two populations are considered to have equivalent genetic diversity and therefore effectively be a single population. It has been shown that it takes only ""One migrant per generation"" to prevent populations from diverging due to drift. Gene flow is an important mechanism for transferring genetic diversity among populations. Migrants change the distribution of genetic diversity within the populations, by modifying the allele frequencies (the"
"a genetic disorder, and of these, about 20% are due to newly arisen germline mutations. Germline In biology and genetics, the germline in a multicellular organism is the population of its bodily cells that are so differentiated or segregated that in the usual processes of reproduction they may pass on their genetic material to the progeny. As a rule this passing-on happens via a process of ""sexual reproduction""; typically it is a process that includes systematic changes to the genetic material, changes that arise during recombination, meiosis and fertilization for example. However, there are many exceptions, including processes and concepts"
"Genome evolution Genome evolution is the process by which a genome changes in structure (sequence) or size over time. The study of genome evolution involves multiple fields such as structural analysis of the genome, the study of genomic parasites, gene and ancient genome duplications, polyploidy, and comparative genomics. Genome evolution is a constantly changing and evolving field due to the steadily growing number of sequenced genomes, both prokaryotic and eukaryotic, available to the scientific community and the public at large. Since the first sequenced genomes became available in the late 1970s, scientists have been using comparative genomics to study the"
"in a broad sense refers to processes of change, from stellar evolution to changes in language. In biology, the meaning is more specific: heritable changes which accumulate over generations of a population. Individual organisms do not evolve in their lifetimes, but variations in the genes they inherit can become more or less common in the population of organisms. Any changes during the lifetime of organisms which are not inherited by their offspring are not part of biological evolution. To Keith Stewart Thomson, the word evolution has at least three distinct meanings: Thomson remarks: ""Change over time is a fact, and"
"Genetic variation Genetic variation means that biological systems – individuals and populations – are different over space. Each gene pool includes various alleles of genes. The variation occurs both within and among populations, supported by individual carriers of the variant genes. Genetic variation is brought about, fundamentally, by mutation, which is a permanent change in the chemical structure of chromosomes. Genetic recombination also produces changes within alleles. Genetic variation among individuals within a population can be identified at a variety of levels. It is possible to identify genetic variation from observations of phenotypic variation in either quantitative traits (traits that"
"Phylogenetics In biology, phylogenetics (Greek: φυλή, φῦλον – ""phylé"", ""phylon"" = tribe, clan, race + γενετικός – ""genetikós"" = origin, source, birth) is the study of the evolutionary history and relationships among individuals or groups of organisms (e.g. species, or populations). These relationships are discovered through phylogenetic inference methods that evaluate observed heritable traits, such as DNA sequences or morphology under a model of evolution of these traits. The result of these analyses is a phylogeny (also known as a phylogenetic tree) – a diagrammatic hypothesis about the history of the evolutionary relationships of a group of organisms. The tips"
"of genetic differences within populations and how these distributions change over time. Changes in the frequency of an allele in a population are mainly influenced by natural selection, where a given allele provides a selective or reproductive advantage to the organism, as well as other factors such as mutation, genetic drift, genetic hitchhiking, artificial selection and migration. Over many generations, the genomes of organisms can change significantly, resulting in evolution. In the process called adaptation, selection for beneficial mutations can cause a species to evolve into forms better able to survive in their environment. New species are formed through the"
"It is the reshuffling of the chromosomes that results in unique combinations of genes in offspring. Since genes interact with one another during the development of an organism, novel combinations of genes produced by sexual reproduction can increase the genetic variability of the population even without new mutations. The genetic variability of a population can also increase when members of that population interbreed with individuals from a different population causing gene flow between the populations. This can introduce genes into a population that were not present before. Evolution is not a random process. Although mutations in DNA are random, natural"
"Epigenome An epigenome consists of a record of the chemical changes to the DNA and histone proteins of an organism; these changes can be passed down to an organism's offspring via transgenerational epigenetic inheritance. Changes to the epigenome can result in changes to the structure of chromatin and changes to the function of the genome. The epigenome is involved in regulating gene expression, development, tissue differentiation, and suppression of transposable elements. Unlike the underlying genome which is largely static within an individual, the epigenome can be dynamically altered by environmental conditions. Epigenetics is a currently active topic in cancer research."
"Genetic divergence Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period of time. In some cases, subpopulations living in ecologically distinct peripheral environments can exhibit genetic divergence from the remainder of a population, especially where the range of a population is very large (see parapatric speciation). The genetic differences among divergent populations can involve silent mutations (that have no effect on the phenotype) or give rise to significant morphological and/or physiological changes. Genetic divergence will always"
"same species or a species that can naturally breed with the host is used the resulting organism is called cisgenic. If genetic engineering is used to remove genetic material from the target organism the resulting organism is termed a knockout organism. In Europe genetic modification is synonymous with genetic engineering while within the United States of America and Canada genetic modification can also be used to refer to more conventional breeding methods. Humans have altered the genomes of species for thousands of years through selective breeding, or artificial selection as contrasted with natural selection. More recently, mutation breeding has used"
"to their offspring is called heredity. In the sense of classical genetics, variation is known as the lack of resemblance in related individuals and can be categorized as discontinuous or continuous. Genes are a fundamental part of DNA that is aligned linearly on a eukaryotic chromosome. Chemical information that is transported and encoded by each gene is referred to as a trait. Many organisms possess two genes for each individual trait that is present within that particular individual. These paired genes that control the same trait is classified as an allele. In an individual, the allelic genes that are expressed"
"Molecular evolution Molecular evolution is the process of change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genetics to explain patterns in these changes. Major topics in molecular evolution concern the rates and impacts of single nucleotide changes, neutral evolution vs. natural selection, origins of new genes, the genetic nature of complex traits, the genetic basis of speciation, evolution of development, and ways that evolutionary forces influence genomic and phenotypic changes. The history of molecular evolution starts in the early 20th"
"Germline In biology and genetics, the germline in a multicellular organism is the population of its bodily cells that are so differentiated or segregated that in the usual processes of reproduction they may pass on their genetic material to the progeny. As a rule this passing-on happens via a process of ""sexual reproduction""; typically it is a process that includes systematic changes to the genetic material, changes that arise during recombination, meiosis and fertilization for example. However, there are many exceptions, including processes and concepts such as various forms of apomixis, autogamy, automixis, cloning, or parthenogenesis. The cells of the"
"that have developed over time: genetic and phenotypic, but there has been a recent movement towards combining these two approaches. All organisms follow a specific sequence in their development, beginning with gestation and ending with death, which is known as the life cycle. Events in between usually include birth, childhood, maturation, reproduction, and senescence, and together these comprise the life history strategy of that organism. The major events in this life cycle are usually shaped by the demographic qualities of the organism. Some are more obvious shifts than others, and may be marked by physical changes—for example, teeth erupting in"
"Genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary. Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Those individuals are more likely to survive to produce offspring bearing that allele. The population will continue for more generations because of the success of these individuals. The academic field"
"Genetic pollution Genetic pollution is a controversial term for uncontrolled gene flow into wild populations. It is defined as “the dispersal of contaminated altered genes from genetically engineered organisms to natural organisms, esp. by cross-pollination”, but has come to be used in some broader ways. It is related to the population genetics concept of gene flow, and genetic rescue, which is genetic material intentionally introduced to increase the fitness of a population. It is called genetic pollution when it negatively impacts on the fitness of a population, such as through outbreeding depression and the introduction of unwanted phenotypes which can"
"or organism may switch gene transcription on or off. A classic example is two seeds of genetically identical corn, one placed in a temperate climate and one in an arid climate. While the average height of the two corn stalks may be genetically determined to be equal, the one in the arid climate only grows to half the height of the one in the temperate climate due to lack of water and nutrients in its environment. The word ""genetics"" stems from the ancient Greek ' meaning ""genitive""/""generative"", which in turn derives from ' meaning ""origin"". The observation that living things"
"Microevolution Microevolution is the change in allele frequencies that occurs over time within a population. This change is due to four different processes: mutation, selection (natural and artificial), gene flow and genetic drift. This change happens over a relatively short (in evolutionary terms) amount of time compared to the changes termed macroevolution which is where greater differences in the population occur. Population genetics is the branch of biology that provides the mathematical structure for the study of the process of microevolution. Ecological genetics concerns itself with observing microevolution in the wild. Typically, observable instances of evolution are examples of microevolution;"
"Recurrent evolution Recurrent evolution is the repeated evolution of a particular character. Most evolution, or changes in allele frequencies from one generation to the next, is the result of drift, or random chance of some alleles getting passed down and others not. Recurrent evolution is when patterns emerge from this stochastic process when looking across populations. These patterns are of particular interest to evolutionary biologists as they can teach people about the underlying forces of evolution. Recurrent evolution is a broad term, but is usually used to describe recurring regimes of selection within or across lineages. While most commonly used"
"trained specialists producing a scientific community who have unfettered access to the whole of society through their scientific knowledge and expertise. Change does indeed happen both within the organism and the organisms properties, the specific species is unable to correct them directly and biological change moves beyond any individual or single member of the species.However, these changes are aimed at the species as a whole and characteristics and traits are retained both at the biological, ecological and environmental level.In the human sciences (biology and genetics)these changes happen at a genetic and biological level which are unalterable and transpire from one"
"Heredity Heredity is the passing on of traits from parents to their offspring, either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic information of their parents. Through heredity, variations between individuals can accumulate and cause species to evolve by natural selection. The study of heredity in biology is genetics. In humans, eye color is an example of an inherited characteristic: an individual might inherit the ""brown-eye trait"" from one of the parents. Inherited traits are controlled by genes and the complete set of genes within an organism's genome is called its genotype. The complete"
"Transformation (genetics) In molecular biology, transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane(s). For transformation to take place, the recipient bacteria must be in a state of competence, which might occur in nature as a time-limited response to environmental conditions such as starvation and cell density, and may also be induced in a laboratory. Transformation is one of three processes for horizontal gene transfer, in which exogenous genetic material passes from one bacterium to another, the other two being conjugation (transfer of"
"Timeline of the evolutionary history of life This timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth. In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization, from kingdoms to species, and individual organisms and molecules, such as DNA and proteins. The similarities between all present day organisms indicate the presence of a common ancestor from which all known species, living and extinct, have diverged through the"
"Character evolution Character evolution is the process by which a character or trait (a certain body part or property of an organism) evolves along the branches of an evolutionary tree. Character evolution usually refers to single changes within a lineage that make this lineage unique from others. These changes are called character state changes and they are often used in the study of evolution to provide a record of common ancestry. Character state changes can be phenotypic changes, nucleotide substitutions, or amino acid substitutions. These small changes in a species can be identifying features of when exactly a new lineage"
"during the acquisition of chloroplasts and mitochondria. ""Gene flow"" is the transfer of alleles from one population to another. Migration into or out of a population may be responsible for a marked change in allele frequencies. Immigration may also result in the addition of new genetic variants to the established gene pool of a particular species or population. There are a number of factors that affect the rate of gene flow between different populations. One of the most significant factors is mobility, as greater mobility of an individual tends to give it greater migratory potential. Animals tend to be more"
"Generation A generation is ""all of the people born and living at about the same time, regarded collectively"". It can also be described as, ""the average period, generally considered to be about thirty years, during which children are born and grow up, become adults, and begin to have children of their own"". In kinship terminology, it is a structural term designating the parent-child relationship. It is also known as biogenesis, reproduction, or procreation in the biological sciences. ""Generation"" is also often used synonymously with ""cohort"" in social science; under this formulation it means ""people within a delineated population who experience"
"Transgenerational epigenetic inheritance Transgenerational epigenetic inheritance is the transmission of information from one generation of an organism to the next (i.e., parent–child transmission) that affects the traits of offspring without alteration of the primary structure of DNA (i.e., the sequence of nucleotides)—in other words, epigenetically. The less precise term ""epigenetic inheritance"" may be used to describe both cell–cell and organism–organism information transfer. Although these two levels of epigenetic inheritance are equivalent in unicellular organisms, they may have distinct mechanisms and evolutionary distinctions in multicellular organisms. For some epigenetically influenced traits, the epigenetic marks can be induced by the environment and"
"a process of mutation in the gene that codes for the protein. If the change is in the gamete, that is, the sperm or egg that join to form a zygote that grows into a human being, the protective mutation will be inherited. Since lethal diseases kill many persons who lack protective mutations, in time, many persons in regions where lethal diseases are endemic come to inherit protective mutations. When the ""P. falciparum"" parasite infects a host cell, it alters the characteristics of the red blood cell membrane, making it ""stickier"" to other cells. Clusters of parasitized red blood cells"
"Gene Revolution The Gene Revolution is an offshoot of the Green Revolution. It's a movement based on the increased use of genetic modification through biotechnology, with the purpose of improving agriculture, food production, and health. Environmental changes play a large role in the backlash against genetically modified organisms (GMOs), while economic growth and a possible decrease in food scarceness serve as strong motivations to keep the movement going. Selective breeding, or ""artificial selection,"" is the process of breeding particular organisms with the goal of achieving a desired trait. Unlike natural selection, which alters organisms over time through ""survival of the"