Evolutionary biology is the subfield of biology that studies the evolutionary processes that produced the diversity of life on Earth, starting from a single common ancestor. These processes include natural selection, common descent, and speciation.
The discipline emerged through what Julian Huxley called the modern synthesis (of the 1930s) of understanding from several previously unrelated fields of biological research, including genetics, ecology, systematics, and paleontology.
Current research has widened to cover the genetic architecture of adaptation, molecular evolution, and the different forces that contribute to evolution including sexual selection, genetic drift and biogeography. The newer field of evolutionary developmental biology ("evo-devo") investigates how embryonic development is controlled, thus creating a wider synthesis that integrates developmental biology with the fields covered by the earlier evolutionary synthesis.
Evolution is the central unifying concept in biology. Biology can be divided in various ways. One way is by the level of biological organisation, from molecular to cell, organism to population. An earlier way is by perceived taxonomic group, with fields such as zoology, botany, and microbiology, reflecting what were once seen as the major divisions of life. A third way is by approach, such as field biology, theoretical biology, experimental evolution, and paleontology. These alternative ways of dividing up the subject can be combined with evolutionary biology to create subfields like evolutionary ecology and evolutionary developmental biology.
More recently, the merge between the biological science and applied sciences gave birth to new fields that are extensions of evolutionary biology, such as evolutionary robotics, engineering, algorithms, economics, and architecture. The basic mechanisms of evolution are applied directly or indirectly to come up with novel designs or solve problems that are difficult to solve otherwise. The research generated in these applied fields in turn contribute to progress, especially thanks to work on evolution in computer science and engineering fields such as mechanical engineering.
The idea of evolution by natural selection was proposed by Charles Darwin in 1859, but evolutionary biology, as an academic discipline in its own right, emerged during the period of the modern synthesis in the 1930s and 1940s. It was not until the 1980s that many universities had departments of evolutionary biology. In the United States, many universities have created departments of molecular and cell biology or ecology and evolutionary biology, in place of the older departments of botany and zoology. Palaeontology is often grouped with earth science.
Microbiology too is becoming an evolutionary discipline, now that microbial physiology and genomics are better understood. The quick generation time of bacteria and viruses such as bacteriophages makes it possible to explore evolutionary questions.
Many biologists have contributed to shaping the modern discipline of evolutionary biology. Theodosius Dobzhansky and E. B. Ford established an empirical research programme. Ronald Fisher, Sewall Wright and J. S. Haldane created a sound theoretical framework. Ernst Mayr in systematics, George Gaylord Simpson in paleontology and G. Ledyard Stebbins in botany helped to form the modern synthesis. James Crow, Richard Lewontin, Dan Hartl, Marcus Feldman, and Brian Charlesworth trained a generation of evolutionary biologists.
First, some fields of evolutionary research try to explain phenomena that were poorly accounted for in the modern evolutionary synthesis. These include speciation, the evolution of sexual reproduction, the evolution of cooperation, the evolution of ageing, and evolvability.
Third, the modern evolutionary synthesis was devised at a time when nobody understood the molecular basis of genes. Today, evolutionary biologists try to determine the genetic architecture of interesting evolutionary phenomena such as adaptation and speciation. They seek answers to questions such as how many genes are involved, how large are the effects of each gene, how interdependent are the effects of different genes, what do the genes do, and what changes happen to them (e.g., point mutations vs. gene duplication or even genome duplication). They try to reconcile the high heritability seen in twin studies with the difficulty in finding which genes are responsible for this heritability using genome-wide association studies.
One challenge in studying genetic architecture is that the classical population genetics that catalysed the modern evolutionary synthesis must be updated to take into account modern molecular knowledge. This requires a great deal of mathematical development to relate DNA sequence data to evolutionary theory as part of a theory of molecular evolution. For example, biologists try to infer which genes have been under strong selection by detecting selective sweeps.
Fourth, the modern evolutionary synthesis involved agreement about which forces contribute to evolution, but not about their relative importance. Current research seeks to determine this. Evolutionary forces include natural selection, sexual selection, genetic drift, genetic draft, developmental constraints, mutation bias and biogeography.
An evolutionary approach is key to much current research in organismal biology and ecology, such as in life history theory. Annotation of genes and their function relies heavily on comparative approaches. The field of evolutionary developmental biology ("evo-devo") investigates how developmental processes work, and compares them in different organisms to determine how they evolved.
Some scientific journals specialise exclusively in evolutionary biology as a whole, including the journals Evolution, Journal of Evolutionary Biology, and BMC Evolutionary Biology. Some journals cover sub-specialties within evolutionary biology, such as the journals Systematic Biology, Molecular Biology and Evolution and its sister journal Genome Biology and Evolution, and Cladistics.
Other journals combine aspects of evolutionary biology with other related fields. For example, Molecular Ecology, Proceedings of the Royal Society of London Series B, The American Naturalist and Theoretical Population Biology have overlap with ecology and other aspects of organismal biology. Overlap with ecology is also prominent in the review journals Trends in Ecology and Evolution and Annual Review of Ecology, Evolution, and Systematics. The journals Genetics and PLoS Genetics overlap with molecular genetics questions that are not obviously evolutionary in nature.
BMC Evolutionary Biology is a peer-reviewed open access scientific journal covering all fields of evolutionary biology, including phylogenetics and palaeontology. It was established in 2001 and is part of a series of BMC journals published by BioMed Central.Biological specificity
In biology, biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species.
Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organisms or constituents of living organisms of being special or doing something special. Each animal or plant species is special. It differs in some way from all other species... biological specificity is the major problem about understanding life."Catagenesis (biology)
Catagenesis is a somewhat archaic term from evolutionary biology referring to evolutionary directions that were considered "retrogressive." It was a term used in contrast to anagenesis, which in present usage denotes the evolution of a single population into a new form without branching lines of descent.Cladogenesis
Cladogenesis is an evolutionary splitting of a parent species into two distinct species, forming a clade.This event usually occurs when a few organisms end up in new, often distant areas or when environmental changes cause several extinctions, opening up ecological niches for the survivors and causing population bottlenecks and founder effects changing allele frequencies of diverging populations compared to their ancestral population. The events that cause these species to originally separate from each other over distant areas may still allow both of the species to have equal chances of surviving, reproducing, and even evolving to better suit their environments while still being two distinct species due to subsequent natural selection, mutations and genetic drift.Cladogenesis is in contrast to anagenesis, in which an ancestral species gradually accumulates change, and eventually, when enough is accumulated, the species is sufficiently distinct and different enough from its original starting form that it can be labeled as a new form - a new species. Note that with anagenesis the lineage in a phylogenetic tree does not split.
To determine whether a speciation event is cladogenesis or anagenesis, researchers may use simulation, evidence from fossils, molecular evidence from the DNA of different living species, or modelling. It has however been debated whether the distinction between cladogenesis and anagenesis is necessary at all in evolutionary theory.Computational biology
Computational biology involves the development and application of data-analytical and theoretical methods, mathematical modeling and computational simulation techniques to the study of biological, ecological, behavioral, and social systems. The field is broadly defined and includes foundations in biology, applied mathematics, statistics, biochemistry, chemistry, biophysics, molecular biology, genetics, genomics, computer science and evolution.Computational biology is different from biological computing, which is a subfield of computer science and computer engineering using bioengineering and biology to build computers, but is similar to bioinformatics, which is an interdisciplinary science using computers to store and process biological data.Evolution (journal)
Evolution: International Journal of Organic Evolution, is a monthly scientific journal that publishes significant new results of empirical or theoretical investigations concerning facts, processes, mechanics, or concepts of evolutionary phenomena and events. Evolution is published by the Society for the Study of Evolution. Its editor-in-chief is Mohamed A. F. Noor.Foster's rule
Foster's rule, also known as the island rule or the island effect, is an ecogeographical rule in evolutionary biology stating that members of a species get smaller or bigger depending on the resources available in the environment. For example, it is known that pygmy mammoths evolved from normal mammoths on small islands. Similar evolutionary paths have been observed in elephants, hippopotamuses, boas, sloths (such as Pygmy three-toed sloth), deer (such as Key deer) and humans.The rule was first stated by J. Bristol Foster in 1964. In it, he compared 116 island species to their mainland varieties. He proposed that certain island creatures evolved into larger versions of themselves (insular gigantism) while others became smaller versions of themselves (insular dwarfism). He proposed the simple explanation that smaller creatures get larger when predation pressure is relaxed because of the absence of some of the predators of the mainland, and larger creatures become smaller when food resources are limited because of land area constraints.The idea was expanded upon in The Theory of Island Biogeography, by Robert MacArthur and Edward O. Wilson. In 1978, Ted J. Case published a longer paper on the topic in the journal Ecology.Gene pool
The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species.Homology (biology)
In biology, homology is the existence of shared ancestry between a pair of structures, or genes, in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats, the arms of primates, the front flippers of whales and the forelegs of dogs and horses are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, and it was explicitly analysed by Pierre Belon in 1555.
In developmental biology, organs that developed in the embryo in the same manner and from similar origins, such as from matching primordia in successive segments of the same animal, are serially homologous. Examples include the legs of a centipede, the maxillary palp and labial palp of an insect, and the spinous processes of successive vertebrae in a vertebral column. Male and female reproductive organs are homologous if they develop from the same embryonic tissue, as do the ovaries and testicles of mammals including humans.
Sequence homology between protein or DNA sequences is similarly defined in terms of shared ancestry. Two segments of DNA can have shared ancestry because of either a speciation event (orthologs) or a duplication event (paralogs). Homology among proteins or DNA is inferred from their sequence similarity. Significant similarity is strong evidence that two sequences are related by divergent evolution from a common ancestor. Alignments of multiple sequences are used to discover the homologous regions.
Homology remains controversial in animal behaviour, but there is suggestive evidence that, for example, dominance hierarchies are homologous across the primates.Index of evolutionary biology articles
This is a list of topics in evolutionary biology.Inversion (evolutionary biology)
In evolutionary developmental biology, inversion refers to the hypothesis that during the course of animal evolution, the structures along the dorsoventral (DV) axis have taken on an orientation opposite that of the ancestral form.
Inversion was first noted in 1822 by the French zoologist Étienne Geoffroy Saint-Hilaire, when he dissected a crayfish (an arthropod) and compared it with the vertebrate body plan. The idea was heavily criticised, but periodically resurfaced, and is now supported by some molecular embryologists.Modern synthesis
Modern synthesis or modern evolutionary synthesis refers to several perspectives on evolutionary biology, namely:
Modern synthesis (20th century), a historical movement in evolutionary biology between about 1918 and 1970
Neo-Darwinism, the state-of-the-art in evolutionary biology, as seen at any chosen time in history from the 1890s to the present day
Extended evolutionary synthesis, an intended revision to the synthesis of the late 20th and early 21st centuriesMolecular Phylogenetics and Evolution
Molecular Phylogenetics and Evolution is a peer-reviewed scientific journal of evolutionary biology and phylogenetics. The journal is edited by D.E. Wildman.Mutant
In biology and especially genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. The term mutant is also applied to a virus with an alteration in its nucleotide sequence whose genome is RNA, rather than DNA. In multicellular eukaryotes, a DNA sequence may be altered in an individual somatic cell that then gives rise to a mutant somatic cell lineage as happens in cancer progression. Also in eukaryotes, alteration of a mitochondrial or plastid DNA sequence may give rise to a mutant lineage that is inherited separately from mutant genotypes in the nuclear genome. The natural occurrence of genetic mutations is integral to the process of evolution. The study of mutants is an integral part of biology; by understanding the effect that a mutation in a gene has, it is possible to establish the normal function of that gene.Population biology
Population biology is an interdisciplinary field combining the areas of ecology and evolutionary biology. Population biology draws on tools from mathematics, statistics, genomics, genetics, and systematics. Population biologists study allele frequency changes (evolution) within populations of the same species (population genetics), and interactions between populations of different species (ecology).Sister group
A sister group or sister taxon is a phylogenetic term denoting the closest relatives of another given unit in an evolutionary tree. The expression is most easily illustrated by a cladogram:
The sister group to A is B; conversely, the sister group to B is A. Groups A and B, together with all other descendants of their most recent common ancestor, form the clade AB. The sister group to clade AB is C.
The whole clade ABC is itself a subtree of a larger tree, which offers yet more sister group branches that are related but farther removed from the leaf nodes, such as A, B, and C.
In cladistic standards, A, B, and C may represent specimens, species, taxon-groups, etc. If they represent species, the term sister species is sometimes used.
The term "sister group" is used in phylogenetic analysis, and only groups identified in the analysis are labeled as sister groups. An example is in birds, whose sister group is commonly cited as the crocodiles, but that is true only when dealing with extant taxa. The bird family tree is rooted in the dinosaurs, making for a number of extinct groups branching off before coming to the last common ancestor of birds and crocodiles. Thus, the term sister group must be seen as a relative term, with the caveat that the sister group is the closest relative only among the groups/species/specimens that are included in the analysis.Systematics
Biological systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: cladograms, phylogenetic trees, phylogenies). Phylogenies have two components: branching order (showing group relationships) and branch length (showing amount of evolution). Phylogenetic trees of species and higher taxa are used to study the evolution of traits (e.g., anatomical or molecular characteristics) and the distribution of organisms (biogeography). Systematics, in other words, is used to understand the evolutionary history of life on Earth.TalkOrigins Archive
The TalkOrigins Archive is a website that presents mainstream science perspectives on the antievolution claims of young-earth, old-earth, and "intelligent design" creationists. With sections on evolution, creationism, geology, astronomy and hominid evolution, the web site provides broad coverage of evolutionary biology and the socio-political antievolution movement.Universal Darwinism
Universal Darwinism (also known as generalized Darwinism, universal selection theory,
or Darwinian metaphysics) refers to a variety of approaches that extend the theory of Darwinism beyond its original domain of biological evolution on Earth. Universal Darwinism aims to formulate a generalized version of the mechanisms of variation, selection and heredity proposed by Charles Darwin, so that they can apply to explain evolution in a wide variety of other domains, including psychology, economics, culture, medicine, computer science and physics.
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