Evolutionary developmental biology (evolution of development or informally, 'evo-devo') is a field of biology that compares the developmental processes of different animals in an attempt to determine the ancestral relationship between organisms and how developmental processes evolved. The discovery of genes regulating development in model organisms allowed for comparisons to be made with genes and genetic networks of related organisms. Biology is the branch of science dealing with the study of life. ... Developmental biology is the study of the process by which organisms grow and develop. ... Binomial name Aptenodytes forsteri Gray, 1844 For other uses, see Animal (disambiguation). ... In biology and ecology, an organism (in Greek organon = instrument) is a complex adaptive system of organs that influence each other in such a way that they function as a more or less stable whole and have properties of life. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. ... Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ...

Introduction

During the 1980s and 1990s more comparative molecular sequence data between different kinds of organisms was amassed and detailed understanding of the molecular basis of the developmental mechanisms which are encoded by those genes has become clearer. Evolutionary developmental biology has arisen in response to these data. The 1980s decade refers to the years from 1980 to 1989, inclusive. ... The 1990s decade refers to the years from 1990 to 1999, inclusive. ... In mathematics, a sequence is a list of objects (or events) arranged in a linear fashion, such that the order of the members is well defined and significant. ... Developmental biology is the study of the process by which organisms grow and develop. ...

Development and the origin of novelty

Among the more surprising and, perhaps, counter-intuitive results of such research in evolutionary developmental biology done in this period is that the diversity of body plans and morphology in organisms across many phyla are not necessarily reflected in diversity at the level of the sequences of genes involved in the regulation of development. Indeed, as Gerhart and Kirschner (1997) have noted, there is an apparent paradox: "where we most expect to find variation, we find conservation, a lack of change". This article is in need of attention from an expert on the subject. ... Comparative anatomy is the study of similarities and differences in organisms. ... Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ...

Even within a species, the occurrence of novel forms within a population do not point to the preexistence of genetic variation sufficient to account for morphological diversity. For example, there is significant variation in limb morphologies amongst salamanders and the differences in segment number in centipedes, even when the genetic variation is low. The gene pool of a species or a population is the complete set of unique alleles that would be found by inspecting the genetic material of every living member of that species or population. ... Suborders Cryptobranchoidea Salamandroidea Sirenoidea Salamander is the common name applied to approximately 500 amphibian vertebrates with slender bodies, short legs, and long tails (order Caudata or Urodela). ... For the Atari video game, see Centipede (video game). ...

A big question then, for evo-devo studies, is: Where does the novelty come from? If the morphological novelty we observe at the level of the different clades is not always reflected in the genome, where does it come from? A clade is group of organisms which share a common ancestor and which includes all decendents of that ancestor. ...

Novelty may arise through several methods including gene duplication and gene regulation. Gene duplication allows fixation of a particular cellular or biochemical function at one locus, leaving the duplicated locus free to fulfill a new function. In contrast, changes in gene regulation, is a "second-order" effect of genes, resulting from the interaction and timing of the genetic network, as distinct from the functioning of the individual genes in the network. Schematic of a region of a chromosome before and after a duplication event Gene duplication occurs when an error in DNA replication leads to the duplication of a region of DNA containing a (generally functional) gene. ... Cells in culture, stained for keratin (red) and DNA (green). ... Biochemistry is the study of the chemistry of life, a bridge between biology and chemistry that studies how complex chemical reactions give rise to life. ... The word locus (plural loci) is Latin for place: In biology and evolutionary computation, a locus is the position of a gene (or other significant sequence) on a chromosome. ... Gene regulation is the general term for cellular control of protein synthesis at the DNA-RNA transcription step. ...

The discovery of the homeotic Hox gene family in vertebrates in the 1980s allowed researchers in developmental biology to empirically assess the relative roles of the above two factors, with respect to their importance in the evolution of morphological diversity. Several biologists, including Sean B. Carroll of the University of Wisconsin suggest that "changes in the cis-regulatory systems of genes" are more significant than "changes in gene number or protein function" (Carroll 2000). A homeobox is a DNA sequence found within genes that are involved in the regulation of development (morphogenesis) of animals, fungi and plants. ... Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... The 1980s decade refers to the years from 1980 to 1989, inclusive. ... Sean B. Carroll is the author of Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom, the first popular summary narrative of evolutionary developmental biology. ... The University of Wisconsin is a public university in the state of Wisconsin. ... CIS is an abbreviation of: Commonwealth of Independent States Canadian Interuniversity Sport Contact Image Sensor CompuServe Information Service Chinese International School Confederacy of Independent Systems (Star Wars) Continuous injection system Communication Information Services Card Information Structure Cisalpino See also uses of the word cis. ...

These researchers argue that the combinatorial nature of transcriptional regulation allows a rich substrate for morphological diversity, since variations in the level, pattern, or timing of gene expression may provide more variation for natural selection to act upon than changes in the gene product alone. Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. Or, in other words, the transfer of genetic information from DNA into RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately... Gene expression, also called protein expression or often simply expression is the process by which a genes DNA sequence is converted into the structures and functions of a cell. ... Charles Darwin in 1859 in his book The Origin of Species defined Natural selection as the principle, by which each slight variation [of a trait], if useful, is preserved. ...

References

• Sean B. Carroll, 2000, "Endless forms: the evolution of gene regulation and morphological diversity", Cell, 101 pp.577-580
• John Gerhart and Marc Kirschner, 1997, Cells, Embryos and Evolution, Blackwell Science.

Sean B. Carroll is the author of Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom, the first popular summary narrative of evolutionary developmental biology. ... This article is about the year 2000. ... Cell is a bi-monthly peer-reviewed scientific journal which publishes novel research in any area of experimental biology that is significant outside its field. ... Professor Marc W. Kirschner is an American systems biologist. ... 1997 (MCMXCVII in Roman) is a common year starting on Wednesday of the Gregorian calendar. ...

Further reading

• Brian Goodwin, 1994, How the Leopard Changed its Spots, Phoenix Giants.
• Leo W. Buss, 1987, The Evolution of Individuality, Princeton University Press.
• Sean B. Carroll, 2005, Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom, W. W. Norton & Company.
• Stephen Jay Gould, Ontogeny and Phylogeny: typically controversial, but a relevant re-appraisal of a defunct concept

This article does not cite its references or sources. ... 1994 (MCMXCIV) was a common year starting on Saturday of the Gregorian calendar, and was designated the International year of the Family. ... Leo W. Buss is a Professor in Yale Universitys departments of geology, geophysics, and ecology and evolutionary biology. ... Sean B. Carroll is the author of Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom, the first popular summary narrative of evolutionary developmental biology. ... Stephen Jay Gould Stephen Jay Gould (September 10, 1941 – May 20, 2002) was an American paleontologist, evolutionary biologist, and historian of science. ...

External links

• [1] A 2000 issue of the Proceedings of the National Academy of Science (PNAS) devoted to "evo-devo" consisting of an editorial, several reviews, and several research articles.

See also

• Animal Evolution
• Evolution of Multicellularity
• Ontogeny
• Ontogeny recapitulates phylogeny
• List of gene families
• Important publications in evolutionary developmental biology