Portal:Evolutionary biology

The Evolutionary Biology Portal

Introduction

Evolutionary biology is a subfield of biology that analyzes the four mechanisms of evolution: natural selection, mutation, genetic drift, and gene flow. Natural selection was independently discovered as the engine of evolution by Charles Darwin and Alfred Russel Wallace, based on patterns in the geographic distribution of species. Gregor Mendel discovered the laws of heredity. R. A. Fisher unified Darwin and Mendel in the modern synthesis.

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. 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. Evolution accounts for the unity and diversity of life on Earth; Theodosius Dobzhansky famously said that nothing in biology makes sense without it. (Full article...)

Selected article -

Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as genetic drift and natural selection act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. The process of evolution has given rise to biodiversity at every level of biological organisation.

The scientific theory of evolution by natural selection was conceived independently by two British naturalists, Charles Darwin and Alfred Russel Wallace, in the mid-19th century as an explanation for why organisms are adapted to their physical and biological environments. The theory was first set out in detail in Darwin's book On the Origin of Species. Evolution by natural selection is established by observable facts about living organisms: (1) more offspring are often produced than can possibly survive; (2) traits vary among individuals with respect to their morphology, physiology, and behaviour; (3) different traits confer different rates of survival and reproduction (differential fitness); and (4) traits can be passed from generation to generation (heritability of fitness). In successive generations, members of a population are therefore more likely to be replaced by the offspring of parents with favourable characteristics for that environment. (Full article...)

List of selected articles

General images -

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

Image 1Speciation 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 2Among 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 3Selection of disease-causing mutations, in a standard table of the genetic code of amino acids (from Mutation)
Image 4The 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 5Five types of chromosomal mutations (from Mutation)
Image 6A gene regulatory network (from Evolutionary developmental biology)
Image 7A covalent adduct between the metabolite of benzo[a]pyrene, the major mutagen in tobacco smoke, and DNA (from Mutation)
Image 8The 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 9Turing'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 10Gaur (Indian bison) can interbreed with domestic cattle. (from Speciation)
Image 11Gene product distributions along the long axis of the early embryo of a fruit fly (from Evolutionary developmental biology)
Image 12Male Drosophila pseudoobscura (from Speciation)
Image 13Phyletic 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 14Homologous 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 15Comparison of allopatric, peripatric, parapatric and sympatric speciation (from Speciation)
Image 16The 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 17Cichlids such as Haplochromis nyererei diversified by sympatric speciation in the Rift Valley lakes. (from Speciation)
Image 18A. Lancelet (a chordate), B. Larval tunicate, C. Adult tunicate. Kowalevsky saw that the notochord (1) and gill slits (5) are shared by tunicates and vertebrates. (from Evolutionary developmental biology)
Image 19A red tulip exhibiting a partially yellow petal due to a somatic mutation in a cell that formed that petal (from Mutation)
Image 20Reinforcement assists speciation by selecting against hybrids. (from Speciation)
Image 21Types of small-scale mutations (from Mutation)
Image 22Gap 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 23Prodryas persephone, a Late Eocene butterfly (from Mutation)
Image 24Embryology 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 25African pygmy kingfisher, showing coloration shared by all adults of that species to a high degree of fidelity. (from Speciation)
Image 26Expression of homeobox (Hox) genes in the fruit fly (from Evolutionary developmental biology)
Image 27Point mutations classified by impact on protein (from Mutation)
Image 28Three major single-chromosome mutations: deletion (1), duplication (2) and inversion (3). (from Mutation)
Image 29Rhagoletis pomonella, the hawthorn fly, appears to be in the process of sympatric speciation. (from Speciation)
Image 30A 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)
Image 31The pax-6 gene controls development of eyes of different types across the animal kingdom. (from Evolutionary developmental biology)
Image 32This figure shows a simplified version of loss-of-function, switch-of-function, gain-of-function, and conservation-of-function mutations. (from Mutation)

Selected picture -

The image depicts the duplication of part of a chromosome.

Did you know... -

... that the idea that molecular evolution is dominated by genetic drift originally took its name from the 1969 paper "Non-Darwinian Evolution"?
... that William King Gregory, a leading authority on vertebrate evolution and the preeminent expert on human dentition, was initially taken in by the Piltdown Man, a hoax which was purported to be an early human?
... that Herbert Spencer, secretary of the Derby Philosophical Society, first suggested the term "survival of the fittest" after reading Charles Darwin's idea of evolution?

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