Evolutionary biology 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...
The tree of life as depicted by Ernst Haeckel in The Evolution of Man (1879) illustrates the 19th-century view of evolution as a progressive process leading towards man. Evolutionary thought, the recognition that species change over time and the perceived understanding of how such processes work, has roots in antiquity—in the ideas of the ancient Greeks , Romans , Chinese , Church Fathers as well as in medieval Islamic science . With the beginnings of modern biological taxonomy in the late 17th century, two opposed ideas influenced Western biological thinking: essentialism , the belief that every species has essential characteristics that are unalterable, a concept which had developed from medieval Aristotelian metaphysics , and that fit well with natural theology ; and the development of the new anti-Aristotelian approach to modern science : as the Enlightenment progressed, evolutionary cosmology and the mechanical philosophy spread from the physical sciences to natural history . Naturalists began to focus on the variability of species; the emergence of palaeontology with the concept of extinction further undermined static views of nature . In the early 19th century prior to Darwinism , Jean-Baptiste Lamarck (1744–1829) proposed his theory of the transmutation of species , the first fully formed theory of evolution .
In 1858 Charles Darwin and Alfred Russel Wallace published a new evolutionary theory, explained in detail in Darwin's On the Origin of Species common descent and a branching tree of life , meaning that two very different species could share a common ancestor. Darwin based his theory on the idea of natural selection : it synthesized a broad range of evidence from animal husbandry , biogeography , geology , morphology , and embryology . Debate over Darwin's work led to the rapid acceptance of the general concept of evolution, but the specific mechanism he proposed, natural selection, was not widely accepted until it was revived by developments in biology that occurred during the 1920s through the 1940s. Before that time most biologists regarded other factors as responsible for evolution. Alternatives to natural selection suggested during "the eclipse of Darwinism " (c. 1880 to 1920) included inheritance of acquired characteristics (neo-Lamarckism ), an innate drive for change (orthogenesis ), and sudden large mutations (saltationism ). Mendelian genetics , a series of 19th-century experiments with pea plant variations rediscovered in 1900, was integrated with natural selection by Ronald Fisher , J. B. S. Haldane , and Sewall Wright during the 1910s to 1930s, and resulted in the founding of the new discipline of population genetics . During the 1930s and 1940s population genetics became integrated with other biological fields, resulting in a widely applicable theory of evolution that encompassed much of biology—the modern synthesis . (Full article...
The following are images from various evolutionary biology-related articles on Wikipedia.
Image 2 The 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 3 The
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 4 Gaur (Indian bison) can interbreed with domestic
cattle . (from
Speciation )
Image 5 Turing'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 6 A red
tulip exhibiting a partially yellow petal due to a
somatic mutation in a cell that formed that petal (from
Mutation )
Image 7 Point mutations classified by impact on protein (from
Mutation )
Image 9 A.
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 10 Rhagoletis pomonella , the hawthorn fly, appears to be in the process of sympatric speciation. (from
Speciation )
Image 11 Embryology 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 12 The 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 13 A 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 14 The
pax-6 gene controls development of eyes of different types across the animal kingdom. (from
Evolutionary developmental biology )
Image 15 Gap 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 16 Three major single-chromosome mutations:
deletion (1),
duplication (2) and
inversion (3). (from
Mutation )
Image 18 Homologous 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 20 Prodryas persephone , a Late
Eocene butterfly (from
Mutation )
Image 21 Gene product distributions along the long axis of the early embryo of a
fruit fly (from
Evolutionary developmental biology )
Image 23 Five types of chromosomal mutations (from
Mutation )
Image 24 This figure shows a simplified version of loss-of-function, switch-of-function, gain-of-function, and conservation-of-function mutations. (from
Mutation )
Image 25 Selection of disease-causing mutations, in a standard table of the
genetic code of
amino acids (from
Mutation )
Image 26 African pygmy kingfisher , showing coloration shared by all adults of that species to a high degree of fidelity. (from
Speciation )
Image 27 Reinforcement assists speciation by
selecting against
hybrids . (from
Speciation )
Image 29 Types of small-scale mutations (from
Mutation )
Image 30 Speciation 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 31 Among 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 32 Phyletic 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 )
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