Editing Phenotypic trait

{{short description|Inherited characteristic of an organism}}
[[File:Deep Blue eye.jpg|thumb|Eye color is an example of a (physical) phenotypic trait]]
A '''phenotypic trait''',<ref>{{Cite book | url=https://books.google.com/books?id=J1GJDAAAQBAJ&q=books.google+character+state+apomorphy&pg=PA169 |title = The Future of Phylogenetic Systematics: The Legacy of Willi Hennig|isbn = 9781107117648|last1 = Williams|first1 = David|last2 = Schmitt|first2 = Michael|last3 = Wheeler|first3 = Quentin|date = 2016-07-21| publisher=Cambridge University Press }}</ref><ref>{{Cite book | url=https://books.google.com/books?id=BU2rAgAAQBAJ&q=books.google+character+state+apomorphy&pg=PA47 |title = The Evolutionary Biology of Flies|isbn = 9780231127004|last1 = Yeates|first1 = David K.|last2 = Wiegmann|first2 = Brian M.|year = 2005| publisher=Columbia University Press }}</ref> simply '''trait''', or '''character state'''<ref>{{Cite web|url=https://evolution.berkeley.edu/evolibrary/article/phylogenetics_06|title=Reconstructing trees: A step by step method – Understanding Evolution|date=29 May 2021}}</ref><ref>{{cite journal |doi=10.1093/sysbio/syv122 |pmid=26715586 |title=Modeling Character Change Heterogeneity in Phylogenetic Analyses of Morphology through the Use of Priors |journal=Systematic Biology |volume=65 |issue=4 |pages=602–611 |year=2016 |last1=Wright |first1=April M |last2=Lloyd |first2=Graeme T |last3=Hillis |first3=David M |doi-access=free }}</ref> is a distinct variant of a [[phenotype|phenotypic]] characteristic of an [[organism]]; it may be either [[heredity|inherited]] or determined environmentally, but typically occurs as a combination of the two.<ref name=Lawrence>Lawrence, Eleanor (2005) ''Henderson's Dictionary of Biology''. Pearson, Prentice Hall. {{ISBN|0-13-127384-1}}</ref>  For example, having [[eye color]] is a ''character'' of an organism, <!---link to "[[abstraction]] of an attribute" is deleted, as none of the content of that article helps the reader of this page---->  while blue, brown and hazel versions of eye color are ''traits''.  The term ''trait'' is generally used in [[genetics]], often to describe the phenotypic expression of different combinations of [[allele]]s in different individual organisms within a single [[Population genetics|population]], such as the famous purple vs. white flower coloration in [[Gregor Mendel]]'s pea plants.  By contrast, in [[systematics]], the term  ''character state'' is employed to describe features that represent fixed diagnostic differences among [[taxa]], such as the absence of tails in [[great apes]], relative to other [[primate]] groups.<ref>{{Cite book |title = Biological Systematics: Principles and Applications|isbn = 9781501752773|last1 = Brower|first1 = Andrew V. Z.|last2 = Schuh|first2 = Randall T.|date = 2021| publisher=Cornell University Press }}</ref>

== Definition ==
A [[phenotypic]] trait is an obvious, observable, and measurable characteristic of an organism; it is the expression of genes in an observable way. An example of a phenotypic trait is a specific hair color or eye color. Underlying genes, that make up the [[genotype]], determine the hair color, but the hair color observed is the phenotype. 

The phenotype is dependent on the genetic make-up of the organism, but is also influenced by the environmental conditions  that the organism was subjected to during its [[ontogenesis|ontogenetic]] development,<ref>*{{Citation | last1 = Campbell | first1 = Neil  | last2 = Reece | first2 = Jane | title = Biology  | publisher =Benjamin Cummings}}</ref> including various [[epigenetic]] processes. 

Regardless of the degree of influence of genotype versus environment, the phenotype encompasses all of the characteristics of an organism, including traits at multiple [[levels of biological organization]], ranging from [[behavior]] and [[evolutionary history of life]] traits (e.g., litter size), through morphology (e.g., body height and composition), physiology (e.g., blood pressure), cellular characteristics (e.g., membrane lipid composition, mitochondrial densities), components of [[biochemical]] pathways, and even [[messenger RNA]].{{citation needed|date=March 2023}}

==Genetic origin of traits in diploid organisms==
Different phenotypic traits are caused by different forms of [[genes]], or [[allele]]s, which arise by [[mutation]] in a single individual and are passed on to successive generations.<ref>{{Cite journal |last1=Gerstein |first1=Mark B. |last2=Bruce |first2=Can |last3=Rozowsky |first3=Joel S. |last4=Zheng |first4=Deyou |last5=Du |first5=Jiang |last6=Korbel |first6=Jan O. |last7=Emanuelsson |first7=Olof |last8=Zhang |first8=Zhengdong D. |last9=Weissman |first9=Sherman |last10=Snyder |first10=Michael |date=June 2007 |title=What is a gene, post-ENCODE? History and updated definition |journal=Genome Research |language=en |volume=17 |issue=6 |pages=669–681 |doi=10.1101/gr.6339607 |pmid=17567988 |issn=1088-9051|doi-access=free }}</ref>

==Biochemistry of dominance and extensions to expression of traits==
The [[biochemistry]] of the intermediate proteins determines how they interact in the cell. Therefore, biochemistry [[philosophy of science|predicts]] how different combinations of alleles will produce varying traits.{{citation needed|date=March 2023}}

Extended expression patterns seen in diploid organisms include facets of [[incomplete dominance]], [[codominance]], and [[multiple alleles]]. Incomplete dominance is the condition in which neither allele dominates the other in one heterozygote. Instead the phenotype is intermediate in heterozygotes. Thus you can tell that each allele is present in the heterozygote.<ref>{{cite web|last=Bailey|first=Regina|title=What is incomplete dominance|url=http://biology.about.com/b/2007/09/29/what-is-incomplete-dominance.htm|publisher=About.com}}</ref> Codominance refers to the allelic relationship that occurs when two alleles are both expressed in the heterozygote, and both phenotypes are seen simultaneously.<ref>{{cite web|last=McClean|first=Philip|title=Variations to Mendel's First Law of Genetics|url=http://www.ndsu.edu/pubweb/~mcclean/plsc431/mendel/mendel2.htm}}</ref> Multiple alleles refers to the situation when there are more than 2 common alleles of a particular gene. Blood groups in humans is a classic example. The [[ABO blood group system|ABO blood group]] proteins are important in
determining blood type in humans, and this is determined by different alleles of the one locus.<ref>{{cite web|last=Unknown|title=Multiple Alleles|url=http://www.occc.edu/biologylabs/Documents/Tutorial_Genetics/Multiple_alleles.htm}}</ref>

==Continuum versus categorical traits==

[[Schizotypy]] is an example of a psychological phenotypic trait found in schizophrenia-spectrum disorders. Studies have shown that gender and age influences the expression of schizotypal traits.<ref name=":0">{{Cite journal|last1=Fonseca-Pedrero|first1=Eduardo|last2=Lemos-Giráldez|first2=Serafín|last3=Paino|first3=Mercedes|last4=Sierra-Baigrie|first4=Susana|last5=Muñiz|first5=José|date=2012-08-01|title=Phenotypic Expression of Schizotypal Traits in an Adolescent Population|url=https://guilfordjournals.com/doi/10.1521/pedi.2012.26.4.539|journal=Journal of Personality Disorders|volume=26|issue=4|pages=539–550|doi=10.1521/pedi.2012.26.4.539|pmid=22867505|issn=0885-579X|url-access=subscription}}</ref> For instance, certain schizotypal traits may develop further during adolescence, whereas others stay the same during this period.<ref name=":0" />

==See also==
{{Portal|Biology}}
* [[Allometric engineering]] of traits
* [[Character displacement]]
* [[Eye color]]
* [[Phene]]
* [[Phenotype]]
* [[Race (biology)]]
* [[Skill]]

==Citations==
{{reflist}}

==References==
* Lawrence, Eleanor (2005) ''Henderson's Dictionary of Biology''. Pearson, Prentice Hall. {{ISBN|0-13-127384-1}}
* {{Citation | last1 = Campbell | first1 = Neil  | last2 = Reece | first2 = Jane | title = Biology  | publisher =Benjamin Cummings
| orig-year =2002 |date=March 2011 | edition =Sixth | chapter = 14 }}

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[[Category:Classical genetics]]