Portal:Evolutionary biology

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Introduction

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 holds that all species are related and gradually change over generations. In a population, the genetic variations affect the phenotypes (physical characteristics) of an organism. These changes in the phenotypes will be an advantage to some organisms, which will then be passed on to 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 investigational range of current research has widened to encompass the genetic architecture of adaptation, molecular evolution, and the different forces that contribute to evolution, such as sexual selection, genetic drift, and biogeography. Moreover, the newer field of evolutionary developmental biology ("evo-devo") investigates how embryogenesis is controlled, thus yielding a wider synthesis that integrates developmental biology with the fields of study covered by the earlier evolutionary synthesis. (Full article...)

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Several organisms are capable of rolling locomotion. However, true wheels and propellers—despite their utility in human vehicles—do not play a significant role in the movement of living things (with the exception of certain flagella, which work like corkscrews). Biologists have offered several explanations for the apparent absence of biological wheels, and wheeled creatures have appeared often in speculative fiction.

Given the ubiquity of wheels in human technology, and the existence of biological analogues of many other technologies (such as wings and lenses), the lack of wheels in nature has seemed, to many scientists, to demand explanation—and the phenomenon is broadly explained by two factors: first, there are several developmental and evolutionary obstacles to the advent of a wheel by natural selection, and secondly, wheels have several drawbacks relative to other means of propulsion (such as walking, running, or slithering) in natural environments, which would tend to preclude their evolution. This environment-specific disadvantage has also led humans in certain regions to abandon wheels at least once in history. (Full article...)

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The following are images from various evolutionary biology-related articles on Wikipedia.

Image 1Point mutations classified by impact on protein (from Mutation)
Image 2The pax-6 gene controls development of eyes of different types across the animal kingdom. (from Evolutionary developmental biology)
Image 3Comparison of allopatric, peripatric, parapatric and sympatric speciation (from Speciation)
Image 4Reinforcement assists speciation by selecting against hybrids. (from Speciation)
Image 5A red tulip exhibiting a partially yellow petal due to a somatic mutation in a cell that formed that petal (from Mutation)
Image 6Speciation via polyploidy: A diploid cell undergoes failed meiosis, producing diploid gametes, which self-fertilize to produce a tetraploid zygote. In plants, this can effectively be a new species, reproductively isolated from its parents, and able to reproduce. (from Speciation)
Image 7Cichlids such as Haplochromis nyererei diversified by sympatric speciation in the Rift Valley lakes. (from Speciation)
Image 8The structure of a eukaryotic protein-coding gene. A mutation in the protein coding region (red) can result in a change in the amino acid sequence. Mutations in other areas of the gene can have diverse effects. Changes within regulatory sequences (yellow and blue) can effect transcriptional and translational regulation of gene expression. (from Mutation)
Image 9Rhagoletis pomonella, the hawthorn fly, appears to be in the process of sympatric speciation. (from Speciation)
Image 10This figure shows a simplified version of loss-of-function, switch-of-function, gain-of-function, and conservation-of-function mutations. (from Mutation)
Image 11The lac operon. Top: repressed. Bottom: active.
1: RNA Polymerase, 2: Repressor, 3: Promoter, 4: Operator, 5: Lactose, 6–8: protein-encoding genes, controlled by the switch, that cause lactose to be digested (from Evolutionary developmental biology)
Image 12African pygmy kingfisher, showing coloration shared by all adults of that species to a high degree of fidelity. (from Speciation)
Image 13Gaur (Indian bison) can interbreed with domestic cattle. (from Speciation)
Image 14Three major single-chromosome mutations: deletion (1), duplication (2) and inversion (3). (from Mutation)
Image 15Gene product distributions along the long axis of the early embryo of a fruit fly (from Evolutionary developmental biology)
Image 16Male Drosophila pseudoobscura (from Speciation)
Image 17Phyletic gradualism, above, consists of relatively slow change over geological time. Punctuated equilibrium, bottom, consists of morphological stability and rare, relatively rapid bursts of evolutionary change. (from Speciation)
Image 18The distribution of fitness effects (DFE) of mutations in vesicular stomatitis virus. In this experiment, random mutations were introduced into the virus by site-directed mutagenesis, and the fitness of each mutant was compared with the ancestral type. A fitness of zero, less than one, one, more than one, respectively, indicates that mutations are lethal, deleterious, neutral, and advantageous. (from Mutation)
Image 19Homologous Hox genes in such different animals as insects and vertebrates control embryonic development and hence the form of adult bodies. These genes have been highly conserved through hundreds of millions of years of evolution. (from Evolutionary developmental biology)
Image 20Selection of disease-causing mutations, in a standard table of the genetic code of amino acids (from Mutation)
Image 21Turing's 1952 paper explained mathematically how patterns such as stripes and spots, as in the giant pufferfish, may arise, without molecular evidence. (from Evolutionary developmental biology)
Image 22A gene regulatory network (from Evolutionary developmental biology)
Image 23Five types of chromosomal mutations (from Mutation)
Image 24Types of small-scale mutations (from Mutation)
Image 25Among the centipedes, all members of the Geophilomorpha are constrained by a developmental bias to have an odd number of segments, whether as few as 27 or as many as 191. (from Evolutionary developmental biology)
Image 26A. Lancelet (a chordate), B. Larval tunicate, C. Adult tunicate. Kowalevsky saw that the notochord (1) and gill slit (5) are shared by tunicates and vertebrates. (from Evolutionary developmental biology)
Image 27A covalent adduct between the metabolite of benzo[a]pyrene, the major mutagen in tobacco smoke, and DNA (from Mutation)
Image 28Gap genes in the fruit fly are switched on by genes such as bicoid, setting up stripes across the embryo which start to pattern the body's segments. (from Evolutionary developmental biology)
Image 29Embryology theories of Ernst Haeckel, who argued for recapitulation of evolutionary development in the embryo, and Karl Ernst von Baer's epigenesis (from Evolutionary developmental biology)
Image 30Prodryas persephone, a Late Eocene butterfly (from Mutation)
Image 31Expression of homeobox (Hox) genes in the fruit fly (from Evolutionary developmental biology)
Image 32A mutation has caused this moss rose plant to produce flowers of different colours. This is a somatic mutation that may also be passed on in the germline. (from Mutation)

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Credit: Splintercellguy

Orange Band, the last Dusky Seaside Sparrow died in 1987 in a captive facility in the Walt Disney World Resort

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Did you know... - show different entries

... that genetic sequence evidence thus allows inference and quantification of genetic relatedness between humans and other apes?
... that American evolutionary biologist Jack Lester King co-authored a provocative 1969 paper, "Non-Darwinian Evolution", on the neutral theory of molecular evolution?
... that maintained gene flow between two populations can also lead to a combination of the two gene pools, reducing the genetic variation between the two groups?

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Stubs: Acritarch | Analogy (biology) | Evolutionary arms race | Genetic erosion | Hoyle's fallacy | Macromutation | Maladaptation | Evolutionary graph theory | Evolutionary landscape | Evolutionary taxonomy | Landrace | Law of Life (more...)
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A complete list of scientific WikiProjects can be found here. See also Wikispecies, a Wikimedia project dedicated to classification of biological species.

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