Array ( [0] => {{about|the transfer of characteristics from parent to offspring|the academic journal|Heredity (journal){{!}}''Heredity'' (journal)|other uses|Heredity (disambiguation)}} [1] => {{Redirect|Bloodline}} [2] => {{Redirect|Hereditary|the 2018 horror film|Hereditary (film){{!}}''Hereditary'' (film)}} [3] => {{Distinguish|text=[[Heritability]], a statistic estimating the degree of genetic variation}} [4] => {{short description|Passing of traits to offspring from the species' parents or ancestor}} [5] => {{Genetics sidebar}} [6] => '''Heredity''', also called '''inheritance''' or '''biological inheritance''', is the passing on of [[Phenotypic trait|traits]] from parents to their offspring; either through [[asexual reproduction]] or [[sexual reproduction]], the offspring [[cell (biology)|cells]] or [[organisms]] acquire the [[genetic information]] of their parents. Through heredity, variations between individuals can accumulate and cause [[species]] to [[evolution|evolve]] by [[natural selection]]. The study of heredity in [[biology]] is [[genetics]]. [7] => [8] => ==Overview== [9] => [[File:Jug Ear Heredity.jpg|thumb|right|150px|Heredity of phenotypic traits: a father and son with [[prominent ear]]s and crowns.]] [10] => [[File:DNA animation.gif|thumb|500px|[[DNA]] structure. [[nucleobase|Bases]] are in the centre, surrounded by phosphate–sugar chains in a [[double helix]].]] [11] => [12] => In humans, [[eye color]] is an example of an inherited characteristic: an individual might inherit the "brown-eye trait" from one of the parents.{{cite journal |author=Sturm RA|author2=Frudakis TN |title=Eye colour: portals into pigmentation genes and ancestry |journal=Trends Genet. |volume=20 |issue=8 |pages=327–332 |date=2004 |pmid=15262401 |doi=10.1016/j.tig.2004.06.010}} Inherited traits are controlled by [[gene]]s and the complete set of genes within an organism's [[genome]] is called its [[genotype]].{{cite journal |author=Pearson H |title=Genetics: what is a gene? |journal=Nature |volume=441 |issue=7092 |pages=398–401 |date=2006 |pmid=16724031 |doi=10.1038/441398a |bibcode = 2006Natur.441..398P |s2cid=4420674|doi-access=free }} [13] => [14] => The complete set of observable traits of the structure and behavior of an organism is called its [[phenotype]]. These traits arise from the interaction of the organism's genotype with the [[Environment (biophysical)|environment]].{{cite journal |author=Visscher PM|author2=Hill WG|author3=Wray NR |title=Heritability in the genomics era – concepts and misconceptions |journal=Nat. Rev. Genet. |volume=9 |issue=4 |pages=255–266 |date=2008 |pmid=18319743 |doi=10.1038/nrg2322 |s2cid=690431}} As a result, many aspects of an organism's phenotype are not inherited. For example, [[sun tanning|suntanned]] skin comes from the interaction between a person's genotype and sunlight;{{cite journal | title=PGC-1 coactivators regulate MITF and the tanning response | author=Shoag J | journal=Mol Cell |date=Jan 2013 | volume=49 | issue=1 | pages=145–157 | doi=10.1016/j.molcel.2012.10.027 | pmid=23201126 | last2=Haq | first2=Rizwan | last3=Zhang | first3=Mingfeng | last4=Liu | first4=Laura | last5=Rowe | first5=Glenn C. | last6=Jiang | first6=Aihua | last7=Koulisis | first7=Nicole | last8=Farrel | first8=Caitlin | last9=Amos | first9=Christopher I.| display-authors=1 | pmc=3753666}} thus, suntans are not passed on to people's children. However, some people tan more easily than others, due to differences in their genotype:{{cite journal | url=http://www.minervamedica.it/en/journals/dermatologia-venereologia/article.php?cod=R23Y2010N01A0037 | title=Genetics of pigmentation and melanoma predisposition | author=Pho LN | author2=Leachman SA | journal=G Ital Dermatol Venereol | date=Feb 2010 | volume=145 | issue=1 | pages=37–45 | pmid=20197744 | access-date=2013-03-26 | archive-date=2019-03-28 | archive-url=https://web.archive.org/web/20190328215053/http://www.minervamedica.it/en/journals/dermatologia-venereologia/article.php?cod=R23Y2010N01A0037 | url-status=live}} a striking example is people with the inherited trait of [[albinism]], who do not tan at all and are very sensitive to [[sunburn]].{{cite journal |author=Oetting WS|author2=Brilliant MH|author3=King RA |title=The clinical spectrum of albinism in humans and by action |journal=Molecular Medicine Today |volume=2 |issue=8 |pages=330–335 |date=1996 |pmid=8796918 |doi=10.1016/1357-4310(96)81798-9}} [15] => [16] => Heritable traits are known to be passed from one generation to the next via [[DNA]], a [[molecule]] that encodes genetic information. DNA is a long [[polymer]] that incorporates four types of [[Base pair|bases]], which are interchangeable. The [[Nucleic acid sequence]] (the sequence of bases along a particular DNA molecule) specifies the genetic information: this is comparable to a sequence of letters spelling out a passage of text.{{cite book |last=Griffiths |first=Anthony, J.F. |title=Introduction to Genetic Analysis |date=2012 |publisher=W.H. Freeman and Company |location=New York |isbn=978-1-4292-2943-2 | page=3 |edition=10th |author2=Wessler, Susan R. |author3=Carroll, Sean B. |author4=Doebley J}} Before a cell divides through [[mitosis]], the DNA is copied, so that each of the resulting two cells will inherit the DNA sequence. A portion of a DNA molecule that specifies a single functional unit is called a [[gene]]; different genes have different sequences of bases. Within [[cell (biology)|cells]], the long strands of DNA form condensed structures called [[chromosome]]s. Organisms inherit genetic material from their parents in the form of [[homologous chromosome]]s, containing a unique combination of DNA sequences that code for genes. The specific location of a DNA sequence within a chromosome is known as a [[locus (genetics)|locus]]. If the DNA sequence at a particular locus varies between individuals, the different forms of this sequence are called [[allele]]s. DNA sequences can change through [[mutation]]s, producing new alleles. If a mutation occurs within a gene, the new allele may affect the trait that the gene controls, altering the phenotype of the organism.{{cite book |last=Futuyma |first=Douglas J. |author-link=Douglas J. Futuyma |date=2005 |title=Evolution |publisher=Sinauer Associates, Inc. |location=Sunderland, Massachusetts |isbn=978-0-87893-187-3 |url-access=registration |url=https://archive.org/details/evolution0000futu}} [17] => [18] => However, while this simple correspondence between an allele and a trait works in some cases, most traits are more complex and are controlled by [[quantitative trait locus|multiple interacting genes]] within and among organisms.{{cite journal |author=Phillips PC |title=Epistasis – the essential role of gene interactions in the structure and evolution of genetic systems |journal=Nat. Rev. Genet. |volume=9 |issue=11 |pages=855–867 |date=2008 |pmid=18852697 |doi=10.1038/nrg2452 |pmc=2689140}}{{cite journal |author=Wu R|author2=Lin M |title=Functional mapping – how to map and study the genetic architecture of dynamic complex traits |journal=Nat. Rev. Genet. |volume=7 |issue=3 |pages=229–237 |date=2006 |pmid=16485021 |doi=10.1038/nrg1804 |s2cid=24301815}} Developmental biologists suggest that complex interactions in genetic networks and communication among cells can lead to heritable variations that may underlie some of the mechanics in [[developmental plasticity]] and [[Canalisation (genetics)|canalization]].{{cite journal|last1=Jablonka |first1=E. |last2=Lamb |first2=M.J. |title=The changing concept of epigenetics |journal=Annals of the New York Academy of Sciences |volume=981 |issue=1 |pages=82–96 |date=2002 |url=http://a-c-elitzur.co.il/uploads/articlesdocs/Jablonka.pdf |doi=10.1111/j.1749-6632.2002.tb04913.x |pmid=12547675 |bibcode=2002NYASA.981...82J |s2cid=12561900 |url-status=dead |archive-url=https://web.archive.org/web/20110511122654/http://a-c-elitzur.co.il/uploads/articlesdocs/Jablonka.pdf |archive-date=2011-05-11}} [19] => [20] => Recent findings have confirmed important examples of heritable changes that cannot be explained by direct agency of the DNA molecule. These phenomena are classed as [[epigenetic]] inheritance systems that are causally or independently evolving over genes. Research into modes and mechanisms of epigenetic inheritance is still in its scientific infancy, but this area of research has attracted much recent activity as it broadens the scope of [[heritability]] and evolutionary biology in general.{{cite journal|last1=Jablonka|first1=E.|last2=Raz|first2=G.|title=Transgenerational epigenetic inheritance: Prevalence, mechanisms, and implications for the study of heredity and evolution|journal=The Quarterly Review of Biology|volume=84|issue=2|pages=131–176|date=2009|url=http://compgen.unc.edu/wiki/images/d/df/JablonkaQtrRevBio2009.pdf|pmid=19606595|doi=10.1086/598822|citeseerx=10.1.1.617.6333|s2cid=7233550|access-date=2011-02-18|archive-date=2011-07-15|archive-url=https://web.archive.org/web/20110715111243/http://compgen.unc.edu/wiki/images/d/df/JablonkaQtrRevBio2009.pdf|url-status=live}} [[DNA methylation]] marking [[chromatin]], self-sustaining [[Metabolism#Evolution|metabolic loops]], gene silencing by [[RNA interference]], and the three dimensional [[Protein structure|conformation]] of proteins (such as [[prions]]) are areas where epigenetic inheritance systems have been discovered at the organismic level.{{cite journal|last1=Bossdorf|first1=O.|last2=Arcuri|first2=D.|last3=Richards|first3=C.L.|last4=Pigliucci|first4=M.|title=Experimental alteration of DNA methylation affects the phenotypic plasticity of ecologically relevant traits in ''Arabidopsis thaliana''|journal=Evolutionary Ecology|volume=24|issue=3|pages=541–553|date=2010|doi=10.1007/s10682-010-9372-7|s2cid=15763479|url=https://boris.unibe.ch/5317/1/10682_2010_Article_9372.pdf|access-date=2019-08-15|archive-date=2020-03-01|archive-url=https://web.archive.org/web/20200301011727/https://boris.unibe.ch/5317/1/10682_2010_Article_9372.pdf|url-status=live}}{{cite book|last1=Jablonka|first1=E.|last2=Lamb|first2=M.|title=Evolution in four dimensions: Genetic, epigenetic, behavioural, and symbolic|date=2005|publisher=MIT Press|url=https://books.google.com/books?id=EaCiHFq3MWsC|isbn=978-0-262-10107-3|access-date=2015-06-27|archive-date=2021-12-27|archive-url=https://web.archive.org/web/20211227223526/https://books.google.com/books?id=EaCiHFq3MWsC|url-status=live}} Heritability may also occur at even larger scales. For example, ecological inheritance through the process of [[niche construction]] is defined by the regular and repeated activities of organisms in their environment. This generates a legacy of effect that modifies and feeds back into the selection regime of subsequent generations. Descendants inherit genes plus environmental characteristics generated by the ecological actions of ancestors.{{cite journal|title=Perspective: Seven reasons (not) to neglect niche construction|last1=Laland|first1=K.N.|last2=Sterelny|first2=K.|journal=Evolution|volume=60|issue=8|pages=1751–1762|date=2006|doi=10.1111/j.0014-3820.2006.tb00520.x|pmid=17089961|doi-access=free}} Other examples of heritability in evolution that are not under the direct control of genes include the inheritance of [[Dual inheritance theory|cultural traits]], [[group selection|group heritability]], and [[symbiogenesis]].{{cite journal|title=Morphogenesis by symbiogenesis |last1=Chapman |first1=M.J. |last2=Margulis |first2=L. |author2-link=Lynn Margulis |journal=International Microbiology |volume=1 |issue=4 |pages=319–326 |date=1998 |url=http://www.im.microbios.org/04december98/14%20Chapman.pdf |pmid=10943381 |url-status=dead |archive-url=https://web.archive.org/web/20140823062546/http://www.im.microbios.org/04december98/14%20Chapman.pdf |archive-date=2014-08-23}}{{cite journal|last1=Bijma|first1=P.|last2=Wade|first2=M.J.|title=The joint effects of kin, multilevel selection and indirect genetic effects on response to genetic selection|journal=Journal of Evolutionary Biology|volume=21|issue=5|pages=1175–1188|date=2008|pmid=18547354|doi=10.1111/j.1420-9101.2008.01550.x|s2cid=7204089|doi-access=free}} These examples of heritability that operate above the gene are covered broadly under the title of [[multilevel selection|multilevel or hierarchical selection]], which has been a subject of intense debate in the history of evolutionary science.{{cite journal|last1=Wilson|first1=D. S.|last2=Wilson|first2=E.O.|title=Rethinking the theoretical foundation of sociobiology|journal=The Quarterly Review of Biology|volume=82|issue=4|date=2007|url=http://evolution.binghamton.edu/dswilson/wp-content/uploads/2010/01/Rethinking-sociobiology.pdf|doi=10.1086/522809|pages=327–348|pmid=18217526|s2cid=37774648|url-status=dead|archive-url=https://web.archive.org/web/20110511235639/http://evolution.binghamton.edu/dswilson/wp-content/uploads/2010/01/Rethinking-sociobiology.pdf|archive-date=2011-05-11}}{{cite journal |title=The hierarchical expansion of sorting and selection: Sorting and selection cannot be equated |last1=Vrba |first1=E.S. |last2=Gould |first2=S.J. |journal=Paleobiology |volume=12 |issue=2 |pages=217–228 |date=1986 |url=http://www.explorelifeonearth.org/cursos/VrbaGould1986sorting.pdf |doi=10.1017/S0094837300013671 |bibcode=1986Pbio...12..217V |s2cid=86593897 |access-date=2011-02-18 |archive-date=2016-08-04 |archive-url=https://web.archive.org/web/20160804063711/http://www.explorelifeonearth.org/cursos/VrbaGould1986sorting.pdf |url-status=dead}} [21] => [22] => ==Relation to theory of evolution== [23] => {{See also|Evolution}} [24] => When [[Charles Darwin]] proposed his theory of [[evolution]] in 1859, one of its major problems was the lack of an underlying mechanism for heredity.{{cite book |last=Griffiths |first=Anthony, J.F. |title=Introduction to Genetic Analysis |date=2012 |publisher=W.H. Freeman and Company |location=New York |isbn=978-1-4292-2943-2 |page=14 |edition=10th |author2=Wessler, Susan R. |author3=Carroll, Sean B. |author4=Doebley, John}} Darwin believed in a mix of blending inheritance and the inheritance of acquired [[phenotypic trait|traits]] ([[pangenesis]]). Blending inheritance would lead to uniformity across populations in only a few generations and then would remove variation from a population on which natural selection could act.{{cite journal | url=http://www.genetics.org/content/183/3/757.full | title=Darwin and Genetics | author=Charlesworth, Brian | author2=Charlesworth, Deborah | name-list-style=amp | journal=Genetics | date=November 2009 | volume=183 | issue=3 | pages=757–766 | doi=10.1534/genetics.109.109991 | pmid=19933231 | pmc=2778973 | access-date=2013-03-26 | archive-date=2019-04-29 | archive-url=https://web.archive.org/web/20190429155439/http://www.genetics.org/content/183/3/757.full | url-status=live}} This led to Darwin adopting some [[Lamarckism|Lamarckian]] ideas in later editions of ''[[On the Origin of Species]]'' and his later biological works.{{cite journal | title=The next evolutionary synthesis: from Lamarck and Darwin to genomic variation and systems biology | author=Bard, Jonathan BL | journal=Cell Communication and Signaling | date=2011 | volume=9 | issue=30 | doi=10.1186/1478-811X-9-30 | pages=30| pmc=3215633 | pmid=22053760 | doi-access=free }} Darwin's primary approach to heredity was to outline how it appeared to work (noticing that traits that were not expressed explicitly in the parent at the time of reproduction could be inherited, that certain traits could be [[sex-linked]], etc.) rather than suggesting mechanisms.{{cn|date=March 2023}} [25] => [26] => Darwin's initial model of heredity was adopted by, and then heavily modified by, his cousin [[Francis Galton]], who laid the framework for the [[biometric]] school of heredity.{{cite web |url=http://www.sciencemuseum.org.uk/broughttolife/people/francisgalton.aspx |title=Francis Galton (1822-1911) |publisher=[[Science Museum, London|Science Museum]] |access-date=March 26, 2013 |archive-date=January 30, 2016 |archive-url=https://web.archive.org/web/20160130202832/http://www.sciencemuseum.org.uk/broughttolife/people/francisgalton.aspx |url-status=dead}} Galton found no evidence to support the aspects of Darwin's pangenesis model, which relied on acquired traits.{{cite journal |title=A new perspective on Darwin's Pangenesis |author=Liu Y. |journal=Biol Rev Camb Philos Soc |date=May 2008 |volume=83 |issue=2 |pages=141–149 |doi=10.1111/j.1469-185X.2008.00036.x |pmid=18429766 |s2cid=39953275}} [27] => [28] => The [[Lamarckism|inheritance of acquired traits]] was shown to have little basis in the 1880s when [[August Weismann]] cut the [[tail]]s off many generations of [[mouse|mice]] and found that their offspring continued to develop tails.{{cite book | title=The Biology of Belief: Unleashing the Power of Consciousness, Matter and Miracles | url=https://archive.org/details/biologyofbeliefu00lipt | url-access=registration | publisher=Hay House, Inc. | author=Lipton, Bruce H. | date=2008 | pages=[https://archive.org/details/biologyofbeliefu00lipt/page/12 12] | isbn=978-1-4019-2344-0}} [29] => [30] => == History == [31] => [[File:Aristotle's model of Inheritance.png|thumb|left|upright=1.4|[[Aristotle's biology#Inheritance|Aristotle's model of inheritance]]. The heat/cold part is largely symmetrical, though influenced on the father's side by other factors, but the form part is not.]] [32] => Scientists in [[Classical antiquity|Antiquity]] had a variety of ideas about heredity: [[Theophrastus]] proposed that male flowers caused female flowers to ripen;{{cite journal | title=Male and female in Theophrastus's botanical works | author=Negbi, Moshe | journal=Journal of the History of Biology | date=Summer 1995 | volume=28 | issue=2 | pages=317–332 | doi=10.1007/BF01059192| s2cid=84754865}} [[Hippocrates]] speculated that "seeds" were produced by various body parts and transmitted to offspring at the time of conception;{{cite book | title=Hippocratic Treatises: On Generation – Nature of the Child – Diseases Ic | publisher=Walter de Gruyter | author=Hipócrates | date=1981 | pages=6 | isbn=978-3-11-007903-6}} and [[Aristotle]] thought that male and female fluids mixed at conception.{{cite web | url=http://plato.stanford.edu/entries/aristotle-biology/ | title=Aristotle's Biology – 5.2. From Inquiry to Understanding; from hoti to dioti. | publisher=Stanford University | date=Feb 15, 2006 | access-date=March 26, 2013 | archive-date=May 7, 2019 | archive-url=https://web.archive.org/web/20190507040441/https://plato.stanford.edu/entries/aristotle-biology/ | url-status=live}} [[Aeschylus]], in 458 BC, proposed the male as the parent, with the female as a "nurse for the young life sown within her".''Eumenides'' 658–661 [33] => [34] => Ancient understandings of heredity transitioned to two debated doctrines in the 18th century. The Doctrine of Epigenesis and the Doctrine of Preformation were two distinct views of the understanding of heredity. The Doctrine of Epigenesis, originated by [[Aristotle]], claimed that an embryo continually develops. The modifications of the parent's traits are passed off to an embryo during its lifetime. The foundation of this doctrine was based on the theory of [[inheritance of acquired traits]]. In direct opposition, the Doctrine of Preformation claimed that "like generates like" where the germ would evolve to yield offspring similar to the parents. The Preformationist view believed procreation was an act of revealing what had been created long before. However, this was disputed by the creation of the [[cell theory]] in the 19th century, where the fundamental unit of life is the cell, and not some preformed parts of an organism. Various hereditary mechanisms, including [[blending inheritance]] were also envisaged without being properly tested or quantified, and were later disputed. Nevertheless, people were able to develop domestic breeds of animals as well as crops through artificial selection. The inheritance of acquired traits also formed a part of early Lamarckian ideas on evolution.{{cn|date=March 2023}} [35] => [36] => During the 18th century, Dutch microscopist [[Antonie van Leeuwenhoek]] (1632–1723) discovered "animalcules" in the sperm of humans and other animals.{{cite web | url=http://www.leben.us/index.php/component/content/article/59-volume-3-issue-4/236-antoni-van-leeuwenhoeks-amazing-little-animalcules | title=Antoni van Leeuwenhoek's Amazing Little "Animalcules" | publisher=Leben | access-date=March 26, 2013 | author=Snow, Kurt | url-status=dead | archive-url=https://web.archive.org/web/20130424173741/http://www.leben.us/index.php/component/content/article/59-volume-3-issue-4/236-antoni-van-leeuwenhoeks-amazing-little-animalcules | archive-date=April 24, 2013}} Some scientists speculated they saw a "little man" ([[homunculus]]) inside each [[spermatozoon|sperm]]. These scientists formed a school of thought known as the "spermists". They contended the only contributions of the female to the next generation were the womb in which the homunculus grew, and prenatal influences of the womb.{{cite encyclopedia|url=http://embryo.asu.edu/view/embryo:125308 |archive-url=https://archive.today/20130409231317/http://embryo.asu.edu/view/embryo:125308 |url-status=dead |archive-date=2013-04-09 |title=Hartsoeker's Homunculus Sketch from Essai de Dioptrique |publisher=Embryo Project Encyclopedia |date=2008 |access-date=March 26, 2013 |author=Lawrence, Cera R. |issn=1940-5030}} An opposing school of thought, the ovists, believed that the future human was in the egg, and that sperm merely stimulated the growth of the egg. Ovists thought women carried eggs containing boy and girl children, and that the gender of the offspring was determined well before conception.{{cite book | title=Individual Development and Evolution: The Genesis of Novel Behavior | publisher=Psychology Press | author=Gottlieb, Gilbert | date=2001 | pages=4 | isbn=978-1-4106-0442-2}} [37] => [38] => An early research initiative emerged in 1878 when [[Alpheus Hyatt]] led an investigation to study the laws of heredity through compiling data on family phenotypes (nose size, ear shape, etc.) and expression of pathological conditions and abnormal characteristics, particularly with respect to the age of appearance. One of the projects aims was to tabulate data to better understand why certain traits are consistently expressed while others are highly irregular.{{Cite book|url=https://books.google.com/books?id=p4o9AQAAIAAJ&q=heredity|title=Scientific American, "Heredity"|date=1878-11-30|publisher=Munn & Company|pages=343|language=en|access-date=2021-08-06|archive-date=2022-05-18|archive-url=https://web.archive.org/web/20220518005249/https://books.google.com/books?id=p4o9AQAAIAAJ&q=heredity|url-status=live}} [39] => [40] => ===Gregor Mendel: father of genetics=== [41] => [[File:Independent assortment & segregation.svg|thumb|Table showing how the genes exchange according to segregation or independent assortment during [[meiosis]] and how this translates into Mendel's laws]] [42] => {{Main|Gregor Mendel}} [43] => {{See also|Modern synthesis (20th century)}} [44] => The idea of particulate inheritance of genes can be attributed to the [[Moravia]]n{{Cite book | last = Henig | first = Robin Marantz | title = The Monk in the Garden : The Lost and Found Genius of Gregor Mendel, the Father of Genetics | publisher = Houghton Mifflin | date = 2001 | isbn = 978-0-395-97765-1 | quote = The article, written by an obscure Moravian monk named Gregor Mendel | url-access = registration | url = https://archive.org/details/monkingardenlost00heni}} monk [[Gregor Mendel]] who published his work on pea plants in 1865. However, his work was not widely known and was rediscovered in 1901. It was initially assumed that [[Mendelian inheritance]] only accounted for large (qualitative) differences, such as those seen by Mendel in his pea plants – and the idea of additive effect of (quantitative) genes was not realised until [[Ronald Fisher|R.A. Fisher]]'s (1918) paper, "[[The Correlation Between Relatives on the Supposition of Mendelian Inheritance]]" Mendel's overall contribution gave scientists a useful overview that traits were inheritable. His pea plant demonstration became the foundation of the study of Mendelian Traits. These traits can be traced on a single locus.Carlson, Neil R. (2010). ''Psychology: the Science of Behavior'', p. 206. Toronto: Pearson Canada. {{ISBN|978-0-205-64524-4}}. {{OCLC|1019975419}} [45] => [46] => ===Modern development of genetics and heredity=== [47] => {{Main|History of genetics|History of evolutionary thought}} [48] => In the 1930s, work by Fisher and others resulted in a combination of Mendelian and biometric schools into the [[Modern synthesis (20th century)|modern evolutionary synthesis]]. The modern synthesis bridged the gap between experimental geneticists and naturalists; and between both and palaeontologists, stating that:Mayr & Provine 1998Mayr E. 1982. ''The growth of biological thought: diversity, evolution & inheritance''. Harvard, Cambs. pp. 567 et seq. [49] => [50] => # All evolutionary phenomena can be explained in a way consistent with known genetic mechanisms and the observational evidence of naturalists. [51] => # Evolution is gradual: small genetic changes, recombination ordered by [[natural selection]]. Discontinuities amongst species (or other taxa) are explained as originating gradually through geographical separation and extinction (not saltation). [52] => # [[Natural selection|Selection]] is overwhelmingly the main mechanism of change; even slight advantages are important when continued. The object of selection is the [[phenotype]] in its surrounding environment. The role of [[genetic drift]] is equivocal; though strongly supported initially by [[Dobzhansky]], it was downgraded later as results from ecological genetics were obtained. [53] => # The primacy of population thinking: the genetic diversity carried in natural populations is a key factor in evolution. The strength of natural selection in the wild was greater than expected; the effect of ecological factors such as niche occupation and the significance of barriers to gene flow are all important. [54] => [55] => The idea that [[speciation]] occurs after populations are reproductively isolated has been much debated.{{cite journal | title=Genetic Divergence, Reproductive Isolation, and Marine Speciation | author=Palumbi, Stephen R. | author-link = Stephen Palumbi | journal=Annual Review of Ecology and Systematics | date=1994 | volume=25 | pages=547–572 | doi=10.1146/annurev.es.25.110194.002555}} In plants, polyploidy must be included in any view of speciation. Formulations such as 'evolution consists primarily of changes in the [[allele frequency|frequencies of alleles]] between one generation and another' were proposed rather later. The traditional view is that developmental biology ('[[evo-devo]]') played little part in the synthesis, but an account of [[Gavin de Beer]]'s work by [[Stephen Jay Gould]] suggests he may be an exception.Gould S.J. ''Ontogeny and phylogeny''. Harvard 1977. pp. 221–222 [56] => [57] => Almost all aspects of the synthesis have been challenged at times, with varying degrees of success. There is no doubt, however, that the synthesis was a great landmark in evolutionary biology.{{cite journal | title=Evolution – The Extended Synthesis. A research proposal persuasive enough for the majority of evolutionary biologists? | author=Handschuh, Stephan | author2=Mitteroecker, Philipp | journal= Human Ethology Bulletin|date=June 2012 | volume=27 | issue=1–2 | pages=18–21 | issn=2224-4476}} It cleared up many confusions, and was directly responsible for stimulating a great deal of research in the post-[[World War II]] era. [58] => [59] => [[Trofim Lysenko]] however caused a backlash of what is now called [[Lysenkoism]] in the [[Soviet Union]] when he emphasised [[Lamarckian]] ideas on the [[inheritance of acquired traits]]. This movement affected agricultural research and led to food shortages in the 1960s and seriously affected the USSR.{{Cite journal|last=Harper|first=Peter S.|date=2017-08-03|title=Human genetics in troubled times and places|journal=Hereditas|volume=155|pages=7|doi=10.1186/s41065-017-0042-4|issn=1601-5223|pmc=5541658|pmid=28794693 |doi-access=free }} [60] => [61] => There is growing evidence that there is transgenerational inheritance of epigenetic changes in humans{{cite journal|last1=Szyf|first1=M|title=Nongenetic inheritance and transgenerational epigenetics|journal=Trends in Molecular Medicine|date=2015|volume=21|issue=2|pages=134–144|doi=10.1016/j.molmed.2014.12.004|pmid=25601643}} and other animals.{{cite journal|last1=Kishimoto|first1=S|display-authors= etal|title=Environmental stresses induce transgenerationally inheritable survival advantages via germline-to-soma communication in Caenorhabditis elegans|journal=Nature Communications|date=2017|volume=8|doi=10.1038/ncomms14031|pmid=28067237|page=14031|hdl=2433/217772|bibcode=2017NatCo...814031K|pmc=5227915}} [62] => [63] => ===Common genetic disorders=== [64] => :*[[Fragile X syndrome]] [65] => :*[[Sickle cell disease]] [66] => :*[[Phenylketonuria]] (PKU) [67] => :*[[Haemophilia]] [68] => [69] => ==Types== [70] => [[File:Autosomal dominant.png|thumb|An example pedigree chart of an autosomal dominant disorder]] [71] => [[File:Autosomal recessive.png|thumb|An example pedigree chart of an autosomal recessive disorder]] [72] => [[File:Sex linked inheritance.png|thumb|An example pedigree chart of a sex-linked disorder (The gene is on the [[X chromosome]].)]] [73] => The description of a mode of biological inheritance consists of three main categories: [74] => [75] => :'''1. Number of involved [[Locus (genetics)|loci]]''' [76] => :*[[Mendelian inheritance|Monogenetic]] (also called "simple") – one [[Locus (genetics)|locus]] [77] => :*[[Oligogenic]] – few loci [78] => :*[[Polygene]]tic – many loci [79] => [80] => :'''2. Involved [[chromosome]]s''' [81] => [82] => :*[[Autosomal]] – loci are not situated on a [[sex chromosome]] [83] => :*[[Gonosomal]] – loci are situated on a [[sex chromosome]] [84] => :**X-chromosomal – loci are situated on the [[X chromosome|X-chromosome]] (the more common case) [85] => :**Y-chromosomal – loci are situated on the [[Y chromosome|Y-chromosome]] [86] => :*[[Mitochondrial]] – loci are situated on the [[mitochondrial DNA]] [87] => [88] => :'''3. Correlation [[genotype]]–[[phenotype]]''' [89] => :*[[Dominance relationship#Dominant allele|Dominant]] [90] => :*Intermediate (also called "[[Codominance|codominant]]") [91] => :*[[Recessive]] [92] => :*[[Overdominance|Overdominant]] [93] => :*[[Underdominance|Underdominant]] [94] => [95] => These three categories are part of every exact description of a mode of inheritance in the above order. In addition, more specifications may be added as follows: [96] => [97] => :'''4. Coincidental and environmental interactions''' [98] => [99] => :*[[Penetrance]] [100] => :**Complete [101] => :**Incomplete (percentual number) [102] => :*[[Expressivity (genetics)|Expressivity]] [103] => :**Invariable [104] => :**Variable [105] => :*[[Heritability]] (in polygenetic and sometimes also in oligogenetic modes of inheritance) [106] => :*Maternal or paternal [[imprinting (genetics)|imprinting]] phenomena (also see [[epigenetics]]) [107] => [108] => :'''5. Sex-linked interactions''' [109] => [110] => :*Sex-linked inheritance ([[gonosomal]] loci) [111] => :*[[Sex-limited]] phenotype expression (e.g., [[cryptorchism]]) [112] => :*Inheritance through the maternal line (in case of [[mitochondrial DNA]] loci) [113] => :*Inheritance through the paternal line (in case of [[Y chromosome|Y-chromosomal]] loci) [114] => [115] => :'''6. Locus–locus interactions''' [116] => :*[[Epistasis]] with other loci (e.g., [[overdominance]]) [117] => :*[[Gene coupling]] with other loci (also see [[Chromosomal crossover|crossing over]]) [118] => :*Homozygotous [[lethal factor]]s [119] => :*[[Semi-lethal factor]]s [120] => [121] => Determination and description of a mode of inheritance is also achieved primarily through statistical analysis of pedigree data. In case the involved loci are known, methods of [[molecular genetics]] can also be employed. [122] => [123] => ===Dominant and recessive alleles=== [124] => An [[allele]] is said to be dominant if it is always expressed in the appearance of an organism (phenotype) provided that at least one copy of it is present. For example, in peas the allele for green pods, ''G'', is dominant to that for yellow pods, ''g''. Thus pea plants with the pair of alleles '''''either''''' ''GG'' (homozygote) '''''or''''' ''Gg'' (heterozygote) will have green pods. The allele for yellow pods is recessive. The effects of this allele are only seen when it is present in both chromosomes, ''gg'' (homozygote). This derives from [[Zygosity]], the degree to which both copies of a chromosome or gene have the same genetic sequence, in other words, the degree of similarity of the alleles in an organism. [125] => [126] => File:Autosomal recessive inheritance for affected enzyme.png|Hereditary defects in [[enzymes]] are generally inherited in an autosomal fashion because there are more non-X chromosomes than X-chromosomes, and a recessive fashion because the enzymes from the unaffected genes are generally sufficient to prevent symptoms in carriers. [127] => Autosomal dominant inheritance for structural protein.png|On the other hand, hereditary defects in structural proteins (such as [[osteogenesis imperfecta]], [[Marfan's syndrome]] and many [[Ehlers–Danlos syndrome]]s) are generally autosomal dominant, because it is enough that some components are defective to make the whole structure dysfunctional. This is a [[Dominant negative mutation|dominant-negative]] process, wherein a mutated gene product adversely affects the non-mutated gene product within the same cell. [128] => [129] => [130] => ==See also== [131] => {{collist|colwidth=30em| [132] => * [[Hard inheritance]] [133] => * [[Lamarckism]] [134] => * [[Heritability]] [135] => * [[Particulate inheritance]] [136] => * [[Non-Mendelian inheritance]] [137] => ** [[Extranuclear inheritance]] [138] => ** [[Uniparental inheritance]] [139] => * [[Epigenetic inheritance]] [140] => ** [[Transgenerational epigenetics#Major controversies in the history of inheritance]] [141] => ** [[Inheritance of acquired characteristics]] [142] => * [[Structural inheritance]] [143] => * [[Blending inheritance]] [144] => }} [145] => [146] => ==References== [147] => {{Reflist}} [148] => [149] => ==External links== [150] => {{Wiktionary}} [151] => * [http://plato.stanford.edu/entries/heredity/ Stanford Encyclopedia of Philosophy entry on Heredity and Heritability] [152] => * [http://embryo.asu.edu/pages/experiments-plant-hybridization-1866-johann-gregor-mendel ""Experiments in Plant Hybridization" (1866), by Johann Gregor Mendel", by A. Andrei at the Embryo Project Encyclopedia] [153] => [154] => {{Genetics}} [155] => {{Family}} [156] => [157] => {{Lysenkoism}} [158] => [159] => {{Authority control}} [160] => [161] => [[Category:Genetics]] [] => )
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Heredity

Heredity is the passing of traits from parents to their offspring through genetic information. This Wikipedia page provides an in-depth overview of the concept of heredity, including its history, mechanisms, and applications.

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This Wikipedia page provides an in-depth overview of the concept of heredity, including its history, mechanisms, and applications. It discusses the study of heredity in various disciplines such as genetics, molecular biology, and evolutionary biology. The page explains the role of genes and DNA in determining hereditary traits, as well as the different patterns of inheritance observed in organisms. It also explores the influence of environment on inherited traits and the interaction between genetics and evolution. Additionally, the page covers topics such as genetic disorders, genetic variation, and modern technologies used in the study of heredity. Overall, the Wikipedia page on heredity offers thorough information on this fundamental biological concept, making it a valuable resource for scientists, students, and anyone interested in understanding how traits are passed down from one generation to the next.

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