Homology ( biology ) - wikipedia Homology ( biology ) For other uses, see Homology ( disambiguation ). The principle of homology : The biological relationships ( shown by colours ) of the bones in the forelimbs of vertebrates were used by Charles Darwin as an argument in favor of evolution. 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. Homology was 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. The term was applied to biology by the anatomist Richard Owen in 1843. 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. Contents 1 History 2 Definition 2.1 Homology vs analogy 2.2 In cladistics 3 In different taxa 3.1 In arthropods 3.2 In mammals 3.3 In plants 3.3. 1 Leaves, stems, and roots 3.3. 2 Flower parts 4 Developmental biology 5 Sequence homology 6 In behaviour 7 Notes 8 References 9 Further reading 10 External links History Pierre Belon compared the skeletons of birds and humans in his Book of Birds ( 1555 ). Homology was noticed by Aristotle ( c. 350 BC ), and was explicitly analysed by Pierre Belon in his 1555 Book of Birds, where he systematically compared the skeletons of birds and humans. The pattern of similarity was interpreted as part of the static great chain of being through the mediaeval and early modern periods : it was not then seen as implying evolutionary change. In the German Naturphilosophie tradition, homology was of special interest as demonstrating unity in nature. In 1790, Goethe stated his foliar theory in his essay `` Metamorphosis of Plants '', showing that flower part are derived from leaves. The serial homology of limbs was described late in the 18th century. The French zoologist Etienne Geoffroy Saint - Hilaire showed in 1818 in his theorie d'analogue ( `` theory of homologues '' ) that structures were shared between fishes, reptiles, birds, and mammals. When Geoffroy went further and sought homologies between Georges Cuvier 's embranchements, such as vertebrates and molluscs, his claims triggered the 1830 Cuvier - Geoffroy debate. Geoffroy stated the principle of connections, namely that what is important is the relative position of different structures and their connections to each other. The Estonian embryologist Karl Ernst von Baer stated what are now called von Baer 's laws in 1828, noting that related animals begin their development as similar embryos and then diverge : thus, animals in the same family are more closely related and diverge later than animals which are only in the same order and have fewer homologies. von Baer 's theory recognises that each taxon ( such as a family ) has distinctive shared features, and that embryonic development parallels the taxonomic hierarchy : not the same as recapitulation theory. The term `` homology '' was first used in biology by the anatomist Richard Owen in 1843 when studying the similarities of vertebrate fins and limbs, contrasting it with the matching term `` analogy '' which he used to describe different structures with the same function. In 1859, Charles Darwin explained homologous structures as meaning that the organisms concerned shared a body plan from a common ancestor, and that taxa were branches of a single tree of life. Definition The front wings of beetles such as this five - horned rhinoceros beetle have evolved into elytra, hard wing - cases. These are homologous with the front wings of other insects. The word homology, coined in about 1656, is derived from the Greek ὁμόλογος homologos from ὁμός homos `` same '' and λόγος logos `` relation ''. The hind wings of Dipteran flies such as this cranefly have evolved divergently to form small club - like halteres. These are homologous with the hind wings of other insects. Biological structures or sequences in different taxa are homologous if they are derived from a common ancestor. Homology thus implies divergent evolution. For example, many insects ( such as dragonflies ) possess two pairs of flying wings. In beetles, the first pair of wings has evolved into a pair of hard wing covers, while in Dipteran flies the second pair of wings has evolved into small halteres used for balance. Similarly, the forelimbs of ancestral vertebrates have evolved into the front flippers of whales, the wings of birds, the running forelegs of dogs, deer, and horses, the short forelegs of frogs and lizards, and the grasping hands of primates including humans. The same major forearm bones ( humerus, radius, and ulna ) are found in fossils of lobe - finned fish such as Eusthenopteron. Homology vs. analogy Sycamore maple fruits have wings analogous but not homologous to a bird 's. Further information : Convergent evolution The opposite of homologous organs are analogous organs which do similar jobs in two taxa that were not present in their last common ancestor but rather evolved separately. For example, the wings of insects and birds evolved independently in widely separated groups, and converged functionally to support powered flight, so they are analogous. Similarly, the wings of a sycamore maple seed and the wings of a bird are analogous but not homologous, as they develop from quite different structures. A structure can be homologous at one level, but only analogous at another. Pterosaur, bird and bat wings are analogous as wings, but homologous as forelimbs because the organ served as a forearm ( not a wing ) in the last common ancestor of tetrapods, and evolved in different ways in the three groups. Thus, in the pterosaurs, the `` wing '' involves both the forelimb and the hindlimb. Analogy is called homoplasy in cladistics, and convergent or parallel evolution in evolutionary biology. In cladistics Further information : Cladistics Specialised terms are used in taxonomic research. Primary homology is the initial hypothesis made by a researcher based on similar structure or anatomical connections, inferring that two characters share an ancestry. Secondary homology is implied by parsimony analysis, where a character that only occurs once on a tree is taken to be homologous. As implied in this definition, many cladists consider homology to be synonymous with synapomorphy, a shared derived character or trait state that distinguishes a clade from other organisms. In different taxa pax6 alterations result in similar changes to eye morphology and function across a wide range of taxa. Homologies provide the fundamental basis for all biological classification, although some may be highly counter-intuitive. For example, deep homologies like the pax6 genes that control the development of the eyes of vertebrates and arthropods were unexpected, as the organs are anatomically dissimilar and appeared to have evolved entirely independently. In arthropods The embryonic body segments ( somites ) of different arthropods taxa have diverged from a simple body plan with many similar appendages which are serially homologous, into a variety of body plans with fewer segments equipped with specialised appendages. The homologies between these have been discovered by comparing genes in evolutionary developmental biology. Hox genes in arthropod segmentation Somite ( body segment ) Trilobite ( Trilobitomorpha ) Spider ( Chelicerata ) Centipede ( Myriapoda ) Insect ( Hexapoda ) Shrimp ( Crustacea ) antennae chelicerae ( jaws and fangs ) antennae antennae 1st antennae 1st legs pedipalps - - 2nd antennae 2nd legs 1st legs mandibles mandibles mandibles ( jaws ) 3rd legs 2nd legs 1st maxillae 1st maxillae 1st maxillae 5 4th legs 3rd legs 2nd maxillae 2nd maxillae 2nd maxillae 6 5th legs 4th legs collum ( no legs ) 1st legs 1st legs 7 6th legs - 1st legs 2nd legs 2nd legs 8 7th legs - 2nd legs 3rd legs 3rd legs 9 8th legs - 3rd legs - 4th legs 10 9th legs - 4th legs - 5th legs Among insects, the stinger of the female honey bee is a modified ovipositor, homologous with ovipositors in other insects such as the Orthoptera, Hemiptera, and those Hymenoptera without stingers. In mammals Further information : Comparative anatomy The three small bones in the middle ear of mammals including humans, the malleus, incus, and stapes, are today used to transmit sound from the eardrum to the inner ear. The malleus and incus develop in the embryo from structures that form jaw bones ( the quadrate and the articular ) in lizards, and in fossils of lizard - like ancestors of mammals. Both lines of evidence show that these bones are homologous, sharing a common ancestor. Among the many homologies in mammal reproductive systems, ovaries and testicles are homologous. Rudimentary organs such as the human tailbone, now much reduced from their functional state, are readily understood as signs of evolution, the explanation being that they were cut down by natural selection from functioning organs when their functions were no longer needed, but make no sense at all if species are considered to be fixed. The tailbone is homologous to the tails of other primates. In plants Leaves, stems, and roots In many plants, defensive or storage structures are made by modifications of the development of primary leaves, stems, and roots. Leaves are variously modified from photosynthetic structures to form the insect - trapping pitchers of pitcher plants, the insect - trapping jaws of Venus flytrap, and the spines of cactuses, all homologous. Primary organs Defensive structures Storage structures Leaves Spines Swollen leaves ( e.g. succulents ) Stems Thorns Tubers ( e.g. potato ), rhizomes ( e.g. ginger ), fleshy stems ( e.g. cacti ) Roots - Root tubers ( e.g. sweet potato ), taproot ( e.g. carrot ) Certain compound leaves of flowering plants are partially homologous both to leaves and shoots, because their development has evolved from a genetic mosaic of leaf and shoot development. One pinnate leaf of European ash Detail of palm leaf Leaf petioles adapted as spines in Fouquieria splendens The very large leaves of the banana, Musa acuminata Succulent water storage leaf of Aloe Insect - trapping leaf of Venus flytrap Insect - trapping leaf of pitcher plant Food storage leaves in an onion bulb Flower parts The ABC model of flower development. Class A genes affect sepals and petals, class B genes affect petals and stamens, class C genes affect stamens and carpels. In two specific whorls of the floral meristem, each class of organ identity genes is switched on. Further information : ABC model of flower development The four types of flower parts, namely carpels, stamens, petals, and sepals, are homologous with and derived from leaves, as Goethe correctly noted in 1790. The development of these parts through a pattern of gene expression in the growing zones ( meristems ) is described by the ABC model of flower development. Each of the four types of flower parts is serially repeated in concentric whorls, controlled by a small number of genes acting in various combinations. Thus, A genes working alone result in sepal formation ; A and B together produce petals ; B and C together create stamens ; C alone produces carpels. When none of the genes are active, leaves are formed. Two more groups of genes, D to form ovules and E for the floral whorls, complete the model. The genes are evidently ancient, as old as the flowering plants themselves. Developmental biology The Cretaceous snake Pachyrhachis problematicus had hind legs ( circled ). Developmental biology can identify homologous structures that arose from the same tissue in embryogenesis. For example, adult snakes have no legs, but their early embryos have limb - buds for hind legs, which are soon lost as the embryos develop. The implication that the ancestors of snakes had hind legs is confirmed by fossil evidence : the Cretaceous snake Pachyrhachis problematicus had hind legs complete with hip bones ( ilium, pubis, ischium ), thigh bone ( femur ), leg bones ( tibia, fibula ) and foot bones ( calcaneum, astragalus ) as in tetrapods with legs today. Sequence homology Main article : Sequence homology Further information : Deep homology and Evolutionary developmental biology A sequence alignment of amino acids for mammalian histone proteins. Sequences conserved across all five species analysed are highlighted in grey. Conservative, semi-conservative, and non-conservative mutations are indicated. As with anatomical structures, sequence homology between protein or DNA sequences is 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 typically inferred from their sequence similarity. Significant similarity is strong evidence that two sequences are related by divergent evolution of a common ancestor. Alignments of multiple sequences are used to indicate which regions of each sequence are homologous. Homologous sequences are orthologous if they are descended from the same ancestral sequence separated by a speciation event : when a species diverges into two separate species, the copies of a single gene in the two resulting species are said to be orthologous. The term `` ortholog '' was coined in 1970 by the molecular evolutionist Walter Fitch. Homologous sequences are paralogous if they were created by a duplication event within the genome. For gene duplication events, if a gene in an organism is duplicated to occupy two different positions in the same genome, then the two copies are paralogous. Paralogous genes often belong to the same species. They can shape the structure of whole genomes and thus explain genome evolution to a large extent. Examples include the Homeobox ( Hox ) genes in animals. These genes not only underwent gene duplications within chromosomes but also whole genome duplications. As a result, Hox genes in most vertebrates are clustered across multiple chromosomes with the HoxA - D clusters being the best studied. Dominance hierarchy behaviour, as in these weeper capuchin monkeys, may be homologous across the primates. In behaviour Main article : Homology ( psychology ) It has been suggested that some behaviours might be homologous, based either on sharing across related taxa or on common origins of the behaviour in an individual 's development, though this remains controversial. For example, D.W. Rajecki and Randall C. Flanery, using data on humans and on nonhuman primates, argue that patterns of behaviour in dominance hierarchies are homologous across the primates. Notes Jump up ^ The alternative terms `` homogeny '' and `` homogenous '' were also used in the late 1800s and early 1900s. However, these terms are now archaic in biology, and the term `` homogenous '' is now generally found as a misspelling of the term `` homogeneous '' which refers to the uniformity of a mixture. Jump up ^ If the two pairs of wings are considered as interchangeable, homologous structures, this may be described as a parallel reduction in the number of wings, but otherwise the two changes are each divergent changes in one pair of wings. Jump up ^ These are coloured in the lead image : humerus brown, radius pale buff, ulna red. References ^ Jump up to : Panchen, A.L. ( 1999 ). `` Homology -- history of a concept ''. Novartis Found Symp ( 222 ) : 5 -- 18. PMID 10332750. ^ Jump up to : Brigandt, Ingo ( 23 November 2011 ). `` Essay : Homology ''. The Embryo Project Encyclopedia. ^ Jump up to : Dornelas, Marcelo Carnier ; Dornelas, Odair ( 2005 ). `` From leaf to flower : Revisiting Goethe 's concepts on the  ̈ metamorphosis  ̈ of plants ''. Brazilian Journal of Plant Physiology. 17 ( 4 ). doi : 10.1590 / S1677 - 04202005000400001. Jump up ^ Sommer, R.J. ( July 2008 ). `` Homology and the hierarchy of biological systems ''. Bioessays. 30 ( 7 ) : 653 -- 658. PMID 18536034. doi : 10.1002 / bies. 20776. Jump up ^ Bower, Frederick Orpen ( 1906 ). `` Plant Morphology ''. Congress of Arts and Science : Universal Exposition, St. Louis, 1904. Houghton, Mifflin. p. 64. Jump up ^ Williams, David Malcolm ; Forey, Peter L. ( 2004 ). Milestones in Systematics. CRC Press. p. 198. ISBN 0 - 415 - 28032 - X. Jump up ^ `` homogeneous, adj. ''. OED Online. March 2016. Oxford University Press. http://www.oed.com/view/Entry/88045 ? ( accessed April 09, 2016 ). Jump up ^ `` homogenous, adj. ''. OED Online. March 2016. Oxford University Press. http://www.oed.com/view/Entry/88055 ? ( accessed April 09, 2016 ). Jump up ^ Wagner, Günter P. ( 2014 ). Homology, Genes, and Evolutionary Innovation. Princeton University Press. pp. 53 -- 54. ISBN 978 - 1 - 4008 - 5146 - 1. elytra have very little similarity with typical wings, but are clearly homologous to forewings. Hence butterflies, flies, and beetles all have two pairs of dorsal appendages that are homologous among species. Jump up ^ Lipshitz, Howard D. ( 2012 ). Genes, Development and Cancer : The Life and Work of Edward B. Lewis. Springer. p. 240. ISBN 978 - 1 - 4419 - 8981 - 9. For example, wing and haltere are homologous, yet widely divergent, organs that normally arise as dorsal appendages of the second thoracic ( T2 ) and third thoracic ( T3 ) segments, respectively. Jump up ^ `` Homology : Legs and Limbs ''. UC Berkeley. Retrieved 15 December 2016. Jump up ^ `` Secret Found to Flight of ' Helicopter Seeds ' ''. LiveScience. 11 June 2009. Retrieved 2 March 2017. Jump up ^ Lentink, D. ; Dickson, W.B. ; van Leeuwen, J.L. ; Dickinson, M.H. ( 12 Jun 2009 ). `` Leading - Edge Vortices Elevate Lift of Autorotating Plant Seeds ''. Science. 324 ( 5933 ) : 1438 -- 1440. doi : 10.1126 / science. 1174196. CS1 maint : Multiple names : authors list ( link ) Jump up ^ Scotland, R.W. ( 2010 ). `` Deep homology : A view from systematics ''. BioEssays. 32 ( 5 ) : 438 -- 449. PMID 20394064. doi : 10.1002 / bies. 200900175. Jump up ^ Cf. Butler, A.B. : Homology and Homoplasty. In : Squire, Larry R. ( Ed. ) : Encyclopedia of Neuroscience, Academic Press, 2009, pp. 1195 -- 1199. Jump up ^ `` Homologous structure vs. analogous structure : What is the difference ? ''. Retrieved 27 September 2016. Jump up ^ Pinna, M.C.C. ( 1991 ). `` Concepts and Tests of Homology in the Cladistic Paradigm ''. Cladistics. 7 ( 4 ) : 367 -- 394. doi : 10.1111 / j. 1096 - 0031.1991. tb00045. x. Jump up ^ Page, Roderick D.M. ; Holmes, Edward C. ( 2009 ). Molecular Evolution : A Phylogenetic Approach. John Wiley & Sons. ISBN 978 - 1 - 4443 - 1336 - 9. ^ Jump up to : Brusca, R.C. ; Brusca, G.J. ( 1990 ). Invertebrates. Sinauer Associates. p. 669. CS1 maint : Multiple names : authors list ( link ) Jump up ^ Carroll, Sean B. ( 2006 ). Endless Forms Most Beautiful. Weidenfeld & Nicolson. pp. 28, 66 -- 69. ISBN 0 - 297 - 85094 - 6. Jump up ^ Novartis Foundation ; Hall, Brian ( 2008 ). Homology. John Wiley. p. 29. ISBN 978 - 0 - 470 - 51566 - 2. Jump up ^ Shing, H. ; Erickson, E.H. ( 1982 ). `` Some ultrastructure of the honeybee ( Apis mellifera L. ) sting ''. Apidologie. 13 ( 3 ) : 203 -- 213. Jump up ^ `` Homology : From jaws to ears -- an unusual example of a homology ''. UC Berkeley. Retrieved 15 December 2016. Jump up ^ Hyde, Janet Shibley ; DeLamater, John D. ( June 2010 ), `` Chapter 5 '' ( PDF ), Understanding Human Sexuality ( 11th ed. ), New York : McGraw - Hill, p. 103, ISBN 978 - 0 - 07 - 338282 - 1 Jump up ^ Larson 2004, p. 112. Jump up ^ `` Homology : Leave it to the plants ''. University of California at Berkeley. Retrieved 7 May 2017. Jump up ^ Sattler R ( 1984 ). `` Homology -- a continuing challenge ''. Systematic Botany. 9 ( 4 ) : 382 -- 94. JSTOR 2418787. doi : 10.2307 / 2418787. Jump up ^ Sattler, R. ( 1994 ). `` Homology, homeosis, and process morphology in plants ''. In Hall, Brian Keith. Homology : the hierarchical basis of comparative biology. Academic Press. pp. 423 -- 75. ISBN 0 - 12 - 319583 - 7. Jump up ^ `` Homologies : developmental biology ''. UC Berkeley. Retrieved 15 December 2016. Jump up ^ `` Clustal FAQ # Symbols ''. Clustal. Retrieved 8 December 2014. Jump up ^ Koonin EV ( 2005 ). `` Orthologs, paralogs, and evolutionary genomics ''. Annual Review of Genetics. 39 : 309 -- 38. PMID 16285863. doi : 10.1146 / annurev. genet. 39.073003. 114725. Jump up ^ Fitch, W.M. ( June 1970 ). `` Distinguishing homologous from analogous proteins ''. Systematic Zoology. 19 ( 2 ) : 99 -- 113. JSTOR 2412448. PMID 5449325. doi : 10.2307 / 2412448. Jump up ^ Zakany, Jozsef ; Duboule, Denis ( 2007 ). `` The role of Hox genes during vertebrate limb development ''. Current Opinion in Genetics & Development. 17 ( 4 ) : 359 -- 366. ISSN 0959 - 437X. PMID 17644373. doi : 10.1016 / j. gde. 2007.05. 011. Jump up ^ Moore, David S ( 2013 ). `` Importing the homology concept from biology into developmental psychology ''. Developmental Psychobiology. 55 ( 1 ) : 13 -- 21. PMID 22711075. doi : 10.1002 / dev. 21015. Jump up ^ Rajecki, D.W. ; Flanery, Randall C. ( 2013 ). Lamb, M.E. ; Brown, A.L., ed. Social Conflict and Dominance in Children : a Case for a Primate Homology. Advances in Developmental Psychology. Taylor and Francis. p. 125. ISBN 978 - 1 - 135 - 83123 - 3. Finally, much recent information on children 's and nonhuman primates ' behavior in groups, a conjunction of hard human data and hard nonhuman primate data, lends credence to our comparison. Our conclusion is that, based on their agreement in several unusual characteristics, dominance patterns are homologous in primates. This agreement of unusual characteristics is found at several levels, including fine motor movement, gross motor movement, and behavior at the group level. CS1 maint : Multiple names : authors list ( link ) Further reading Brigandt, Ingo ( 2011 ) `` Essay : Homology. '' In : The Embryo Project Encyclopedia. ISSN 1940 - 5030. http://embryo.asu.edu/handle/10776/1754 Carroll, Sean B. ( 2006 ). Endless Forms Most Beautiful. New York : W.W. Norton & Co. ISBN 0 - 297 - 85094 - 6. Carroll, Sean B. ( 2006 ). The making of the fittest : DNA and the ultimate forensic record of evolution. New York : W.W. Norton & Co. ISBN 0 - 393 - 06163 - 9. DePinna, M.C. ( 1991 ). `` Concepts and tests of homology in the cladistic paradigm ''. Cladistics. 7 ( 4 ) : 367 -- 94. doi : 10.1111 / j. 1096 - 0031.1991. tb00045. x. Dewey, C.N. ; Pachter, L. ( April 2006 ). `` Evolution at the nucleotide level : the problem of multiple whole - genome alignment ''. Human Molecular Genetics. 15 ( Spec No 1 ) : R51 -- 6. PMID 16651369. doi : 10.1093 / hmg / ddl056. CS1 maint : Multiple names : authors list ( link ) Fitch, W.M. ( May 2000 ). `` Homology a personal view on some of the problems ''. Trends in Genetics. 16 ( 5 ) : 227 -- 31. PMID 10782117. doi : 10.1016 / S0168 - 9525 ( 00 ) 02005 - 9. Gegenbaur, G. ( 1898 ). Vergleichende Anatomie der Wirbelthiere... Leipzig. Haeckel, Еrnst ( 1866 ). Generelle Morphologie der Organismen. Bd 1 - 2. Вerlin. Larson, Edward J. ( 2004 ). Evolution : The Remarkable History of Scientific Theory. Modern Library. ISBN 0 - 679 - 64288 - 9. Owen, Richard ( 1847 ). On the archetype and homologies of the vertebrate skeleton. London. Mindell D.P., Meyer A. ( 2001 ). `` Homology evolving '' ( PDF ). Trends in Ecology and Evolution. 16 ( 8 ) : 434 -- 40. doi : 10.1016 / S0169 - 5347 ( 01 ) 02206 - 6. Archived from the original ( PDF ) on 2010 - 06 - 27. Kuzniar, A. ; van Ham, R.C. ; Pongor, S. ; Leunissen, J.A. ( November 2008 ). `` The quest for orthologs : finding the corresponding gene across genomes ''. Trends Genet. 24 ( 11 ) : 539 -- 51. PMID 18819722. doi : 10.1016 / j. tig. 2008.08. 009. External links Media related to Homology at Wikimedia Commons Evolutionary biology Evolutionary history of life Index of evolutionary biology articles Introduction Outline of evolution Timeline of evolution Evolution Abiogenesis Adaptation Adaptive radiation Cladistics Coevolution Common descent Cospeciation Convergence Divergence Earliest known life forms Evidence of common descent Extinction Event Gene - centered view Homology Last universal common ancestor Macroevolution Microevolution Origin of life Panspermia Parallel evolution Prehistoric Autopsy Speciation Taxonomy Population genetics Biodiversity Gene flow Genetic drift Mutation Natural selection Variation Development Canalisation Evolutionary developmental biology Inversion Modularity Phenotypic plasticity Of taxa Birds origin Brachiopods Cephalopods Dinosaurs Fish Fungi Insects butterflies Life Mammals cats dogs dolphins and whales horses primates humans lemurs sea cows wolves Molluscs Plants Reptiles Spiders Tetrapods Viruses influenza Of organs Cell DNA Flagella Eukaryotes symbiogenesis chromosome endomembrane system mitochondria nucleus plastids In animals eye hair auditory ossicle nervous system brain Of processes Aging Death Programmed cell death Avian flight Biological complexity Cooperation Color vision in primates Emotion Empathy Ethics Eusociality Immune system Metabolism Monogamy Morality Mosaic evolution Multicellularity Sexual reproduction Gamete differentiation / sexes Life cycles / nuclear phases Mating types Sex - determination Snake venom Tempo and modes Gradualism / Punctuated equilibrium / Saltationism Micromutation / Macromutation Uniformitarianism / Catastrophism Speciation Allopatric Anagenesis Catagenesis Cladogenesis Ecological Hybrid Parapatric Peripatric Reinforcement Sympatric History Renaissance and Enlightenment Transmutation of species Charles Darwin On the Origin of Species History of paleontology Transitional fossil The eclipse of Darwinism Modern synthesis History of molecular evolution Extended evolutionary synthesis Philosophy Darwinism Alternatives to evolution by natural selection Catastrophism Lamarckism Orthogenesis Mutationism Saltationism Structuralism Spandrel Theistic Vitalism Related Biogeography Ecological genetics Molecular evolution Phylogenetics Tree Polymorphism Protocell Systematics Commons Portal WikiProject Fins, limbs and wings Fins Aquatic locomotion Cephalopod fin Fish locomotion Fin and flipper locomotion Caudal fin Dorsal fin Fish fin flipper Lobe - finned fish Ray - finned fish Pectoral fins Limbs Limb development Limb morphology digitigrade plantigrade unguligrade uniped biped facultative biped triped quadruped Arthropod Cephalopod Tetrapod dactyly Digit Wings Flying and gliding animals Bat wing Bird wing keel skeleton feathers Insect wing Pterosaur wing Wingspan Evolution Evolution of fish Evolution of tetrapods Evolution of birds Origin of birds Origin of avian flight Evolution of cetaceans Comparative anatomy Convergent evolution Analogous structures Homologous structures Related Animal locomotion Gait Robot locomotion Samara Terrestrial locomotion Tradeoffs for locomotion in air and water Rotating locomotion Undulatory locomotion Retrieved from `` https://en.wikipedia.org/w/index.php?title=Homology_(biology)&oldid=800123278 '' Categories : Evolutionary biology Phylogenetics Comparative anatomy Hidden categories : CS1 maint : Multiple names : authors list Good articles Use dmy dates from April 2017 Talk Contents About Wikipedia Aragonés Български Bosanski Català Čeština Dansk Deutsch Eesti Español Esperanto فارسی Français Gaeilge Galego 한국어 Հայերեն Bahasa Indonesia Italiano עברית ქართული Қазақша Kreyòl ayisyen Кыргызча Latviešu Limburgs La. lojban. 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Question: what term describes features that are similar in structure but different in function
Answer: homology