Editing Camouflage (section)

=== Genetics ===

Camouflage does not have a single genetic origin. However, studying the genetic components of camouflage in specific organisms illuminates the various ways that crypsis can evolve among lineages. Many [[cephalopod]]s have the ability to actively camouflage themselves, controlling crypsis through neural activity. For example, the genome of the common cuttlefish includes 16 copies of the [[reflectin]] gene, which grants the organism remarkable control over coloration and iridescence.<ref>{{cite journal |last1=Song |first1=Weiwei |last2=Li |first2=Ronghua |last3=Zhao |first3=Yun |last4=Migaud |first4=Herve |last5=Wang |first5=Chunlin |last6=Bekaert |first6=Michaël |display-authors=3 |date=15 February 2021 |title=Pharaoh Cuttlefish, Sepia pharaonis, Genome Reveals Unique Reflectin Camouflage Gene Set |journal=Frontiers in Marine Science |volume=8 |pages=639670 |doi=10.3389/fmars.2021.639670 |issn=2296-7745|doi-access=free |bibcode=2021FrMaS...839670S |hdl=1893/32292 |hdl-access=free }}</ref> The reflectin gene is thought to have originated through transposition from symbiotic ''[[Aliivibrio fischeri]]'' bacteria, which provide bioluminescence to its hosts. While not all cephalopods use [[active camouflage]], ancient cephalopods may have inherited the gene horizontally from symbiotic ''A. fischeri'', with divergence occurred through subsequent gene duplication (such as in the case of ''Sepia officinalis'') or gene loss (as with cephalopods with no active camouflage capabilities).<ref>{{cite journal |last1=Guan |first1=Zhe |last2=Cai |first2=Tiantian |last3=Liu |first3=Zhongmin |last4=Dou |first4=Yunfeng |last5=Hu |first5=Xuesong |last6=Zhang |first6=Peng |last7=Sun |first7=Xin |last8=Li |first8=Hongwei |last9=Kuang |first9=Yao |last10=Zhai |first10=Qiran |last11=Ruan |first11=Hao |date=September 2017 |title=Origin of the Reflectin Gene and Hierarchical Assembly of Its Protein |journal=[[Current Biology]] |volume=27 |issue=18 |pages=2833–2842.e6 |doi=10.1016/j.cub.2017.07.061|pmid=28889973 |s2cid=9974056 |doi-access=free |bibcode=2017CBio...27E2833G }}</ref><sup>[3]</sup> This is unique as an instance of camouflage arising as an instance of [[horizontal gene transfer]] from an [[endosymbiont]]. However, other methods of horizontal gene transfer are common in the evolution of camouflage strategies in other lineages. [[Peppered moth]]s  and [[Phasmatodea|walking stick insects]]  both have camouflage-related genes that stem from transposition events.<ref>{{cite journal |last1=van't Hof |first1=Arjen E. |last2=Campagne |first2=Pascal |last3=Rigden |first3=Daniel J. |last4=Yung |first4=Carl J. |last5=Lingley |first5=Jessica |last6=Quail |first6=Michael A. |last7=Hall |first7=Neil |last8=Darby |first8=Alistair C. |last9=Saccheri |first9=Ilik J. |date=June 2016 |title=The industrial melanism mutation in British peppered moths is a transposable element |url=http://www.nature.com/articles/nature17951 |journal=[[Nature (journal)|Nature]] |volume=534 |issue=7605 |pages=102–105 |doi=10.1038/nature17951 |pmid=27251284 |bibcode=2016Natur.534..102H |s2cid=3989607 |issn=0028-0836}}</ref><ref>{{cite journal |last1=Werneck |first1=Jane Margaret Costa de Frontin |last2=Torres |first2=Lucas |last3=Provance |first3=David Willian |last4=Brugnera |first4=Ricardo |last5=Grazia |first5=Jocelia |date=3 December 2021 |title=First Report of Predation by a Stink Bug on a Walking-Stick Insect with Reflections on Evolutionary Mechanisms for Camouflage |doi=10.21203/rs.2.10812/v1 |s2cid=240967012 }}</ref>

The [[Agouti (coloration)|Agouti]] genes are orthologous genes involved in camouflage across many lineages. They produce yellow and red coloration ([[Melanin#Pheomelanin|phaeomelanin]]), and work in competition with other genes that produce black (melanin) and brown (eumelanin) colours.<ref>{{cite journal |last1=Voisey |first1=Joanne |last2=Van Daal |first2=Angela |date=February 2002 |title=Agouti: from Mouse to Man, from Skin to Fat |url=http://doi.wiley.com/10.1034/j.1600-0749.2002.00039.x |journal=Pigment Cell Research |volume=15 |issue=1 |pages=10–18 |doi=10.1034/j.1600-0749.2002.00039.x |pmid=11837451 }}</ref> In [[Eastern deer mouse|eastern deer mice]], over a period of about 8000 years the single agouti gene developed 9 mutations that each made expression of yellow fur stronger under natural selection, and largely eliminated melanin-coding black fur coloration.<ref>{{cite journal |last1=Pfeifer |first1=Susanne P |last2=Laurent |first2=Stefan |last3=Sousa |first3=Vitor C. |last4=Linnen |first4=Catherine R. |last5=Foll |first5=Matthieu |last6=Excoffier |first6=Laurent |last7=Hoekstra |first7=Hopi E. |last8=Jensen |first8=Jeffrey D. |display-authors=3 |date=2018-01-15 |title=The Evolutionary History of Nebraska Deer Mice: Local Adaptation in the Face of Strong Gene Flow |url=http://dx.doi.org/10.1093/molbev/msy004 |journal=Molecular Biology and Evolution |volume=35 |issue=4 |pages=792–806 |doi=10.1093/molbev/msy004 |pmid=29346646 |pmc=5905656 |issn=0737-4038}}</ref> On the other hand, all black [[Cat|domesticated cats]] have deletions of the agouti gene that prevent its expression, meaning no yellow or red color is produced. The evolution, history and widespread scope of the agouti gene shows that different organisms often rely on orthologous or even identical genes to develop a variety of camouflage strategies.<ref>{{cite journal |last1=Eizirik |first1=Eduardo |last2=Yuhki |first2=Naoya |last3=Johnson |first3=Warren E. |last4=Menotti-Raymond |first4=Marilyn |last5=Hannah |first5=Steven S. |last6=O'Brien |first6=Stephen J. |display-authors=3 |date=March 2003 |title=Molecular Genetics and Evolution of Melanism in the Cat Family |journal=Current Biology |volume=13 |issue=5 |pages=448–453 |doi=10.1016/S0960-9822(03)00128-3 |pmid=12620197 |s2cid=19021807 |doi-access=free |bibcode=2003CBio...13..448E }}</ref>