Editing Capsaicin (section)

== Evolution ==
The ''Capsicum'' genus split from ''Solanaceae'' 19.6 million years ago, 5.4 million years after the appearance of ''Solanaceae'', and is native only to the Americas.<ref>{{Cite journal | vauthors = Yang HJ, Chung KR, Kwon DY |date=2017-09-01 |title=DNA sequence analysis tells the truth of the origin, propagation, and evolution of chili (red pepper) |journal=Journal of Ethnic Foods |language=en |volume=4 |issue=3 |pages=154–162 |doi=10.1016/j.jef.2017.08.010 |s2cid=164335348 |issn=2352-6181|doi-access=free }}</ref> Chilies only started to quickly evolve in the past 2 million years into markedly different species. This evolution can be partially attributed to a key compound found in peppers, 8-methyl-N-vanillyl-6-nonenamide, otherwise known as capsaicin. Capsaicin evolved similarly across species of chilies that produce capsaicin. Its evolution over the course of centuries is due to [[genetic drift]] and [[natural selection]], across the genus ''[[Capsicum]]''.  Despite the fact that chilies within the ''Capsicum'' genus are found in diverse environments, the capsaicin found within them all exhibit similar properties that serve as defensive and adaptive features. Capsaicin evolved to preserve the [[Fitness (biology)|fitness]] of peppers against fungi infections, insects, and [[Seed predation|granivorous]] mammals.<ref>{{cite journal | vauthors = Tewksbury JJ, Reagan KM, Machnicki NJ, Carlo TA, Haak DC, Peñaloza AL, Levey DJ | title = Evolutionary ecology of pungency in wild chilies | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 105 | issue = 33 | pages = 11808–11811 | date = August 2008 | pmid = 18695236 | pmc = 2575311 | doi = 10.1073/pnas.0802691105 | bibcode = 2008PNAS..10511808T | doi-access = free }}</ref>

=== Antifungal properties ===
Capsaicin acts as an antifungal agent in four primary ways. First, capsaicin inhibits the metabolic rate of the cells that make up the fungal biofilm.<ref>{{cite journal | vauthors = Behbehani JM, Irshad M, Shreaz S, Karched M | title = Anticandidal Activity of Capsaicin and Its Effect on Ergosterol Biosynthesis and Membrane Integrity of ''Candida albicans'' | journal = International Journal of Molecular Sciences | volume = 24 | issue = 2 | pages = 1046 | date = January 2023 | pmid = 36674560 | doi = 10.3390/ijms24021046 | pmc = 9860720 | doi-access = free }}</ref> This inhibits the area and growth rate of the fungus, since the biofilm creates an area where a fungus can grow and adhere to the chili in which capsaicin is present.<ref>{{cite journal | vauthors = Costa-Orlandi CB, Sardi JC, Pitangui NS, de Oliveira HC, Scorzoni L, Galeane MC, Medina-Alarcón KP, Melo WC, Marcelino MY, Braz JD, Fusco-Almeida AM, Mendes-Giannini MJ | title = Fungal Biofilms and Polymicrobial Diseases | journal = Journal of Fungi | volume = 3 | issue = 2 | pages = 22 | date = May 2017 | pmid = 29371540 | doi = 10.3390/jof3020022 | pmc = 5715925 | doi-access = free }}</ref> Capsaicin also inhibits fungal [[hypha]]e formation, which impacts the amount of nutrients that the rest of the fungal body can receive.<ref>{{Cite web |title=How fungi are constructed |url=http://website.nbm-mnb.ca/mycologywebpages/NaturalHistoryOfFungi/Thallus.html#:~:text=Hyphae%20perform%20a%20variety%20of,the%20thallus%20(fungus%20body). |access-date=2023-05-05 |website=website.nbm-mnb.ca}}</ref> Thirdly, capsaicin disrupts the structure<ref name="Yang-2017">{{cite journal | vauthors = Yang F, Zheng J | title = Understand spiciness: mechanism of TRPV1 channel activation by capsaicin | journal = Protein & Cell | volume = 8 | issue = 3 | pages = 169–177 | date = March 2017 | pmid = 28044278 | pmc = 5326624 | doi = 10.1007/s13238-016-0353-7 }}</ref> of fungal cells and the fungal cell membranes. This has consequential negative impacts on the integrity of fungal cells and their ability to survive and proliferate. Additionally, the [[ergosterol]] synthesis of growing fungi decreases in relation to the amount of capsaicin present in the growth area. This impacts the fungal cell membrane, and how it is able to reproduce and adapt to stressors in its environment.<ref>{{cite journal | vauthors = Jordá T, Puig S | title = Regulation of Ergosterol Biosynthesis in ''Saccharomyces cerevisiae'' | journal = Genes | volume = 11 | issue = 7 | pages = 795 | date = July 2020 | pmid = 32679672 | pmc = 7397035 | doi = 10.3390/genes11070795 | doi-access = free }}</ref>

=== Insecticidal properties ===
Capsaicin deters insects in multiple ways. The first is by deterring insects from laying their eggs on the pepper due to the effects capsaicin has on these insects.<ref>{{cite journal | vauthors = Li Y, Bai P, Wei L, Kang R, Chen L, Zhang M, Tan EK, Liu W | title = Capsaicin Functions as Drosophila Ovipositional Repellent and Causes Intestinal Dysplasia | journal = Scientific Reports | volume = 10 | issue = 1 | pages = 9963 | date = June 2020 | pmid = 32561812 | pmc = 7305228 | doi = 10.1038/s41598-020-66900-2 | bibcode = 2020NatSR..10.9963L }}</ref> Capsaicin can cause intestinal [[dysplasia]] upon ingestion, disrupting insect metabolism and causing damage to cell membranes within the insect.<ref>{{Cite web |title=Capsaicin Technical Fact Sheet |url=http://npic.orst.edu/factsheets/archive/Capsaicintech.html#references |access-date=2023-05-05 |website=npic.orst.edu}}</ref><ref>{{cite journal | vauthors = Claros Cuadrado JL, Pinillos EO, Tito R, Mirones CS, Gamarra Mendoza NN | title = Insecticidal Properties of Capsaicinoids and Glucosinolates Extracted from ''Capsicum chinense'' and ''Tropaeolum tuberosum'' | journal = Insects | volume = 10 | issue = 5 | pages = 132 | date = May 2019 | pmid = 31064092 | pmc = 6572632 | doi = 10.3390/insects10050132 | doi-access = free }}</ref> This in turn disrupts the standard feeding response of insects.

=== Seed dispersion and deterrents against granivorous mammals ===
[[Seed predation|Granivorous]] mammals pose a risk to the propagation of chilies because their molars grind the seeds of chilies, rendering them unable to grow into new chili plants.<ref>{{cite journal | vauthors = Levey DJ, Tewksbury JJ, Cipollini ML, Carlo TA | title = A field test of the directed deterrence hypothesis in two species of wild chili | journal = Oecologia | volume = 150 | issue = 1 | pages = 61–68 | date = November 2006 | pmid = 16896774 | doi = 10.1007/s00442-006-0496-y | bibcode = 2006Oecol.150...61L | s2cid = 10892233 }}</ref><ref name="Tewksbury Nabhan 2001"/> As a result, modern chilies evolved defense mechanisms to mitigate the risk of granivorous mammals. While capsaicin is present at some level in every part of the pepper, the chemical has its highest concentration in the tissue near the seeds within chilies.<ref name="NMSU Q&A 2005" /> Birds are able to eat chilies, then disperse the seeds in their excrement, enabling propagation.<ref name="Tewksbury Nabhan 2001"/>

=== Adaptation to varying moisture levels ===
Capsaicin is a potent defense mechanism for chilies, but it does come at a cost. Varying levels of capsaicin in chilies currently appear to be caused by an evolutionary split between surviving in dry environments, and having defense mechanisms against fungal growth, insects, and granivorous mammals.<ref>{{cite journal | vauthors = Haak DC, McGinnis LA, Levey DJ, Tewksbury JJ | title = Why are not all chilies hot? A trade-off limits pungency | journal = Proceedings. Biological Sciences | volume = 279 | issue = 1735 | pages = 2012–2017 | date = May 2012 | pmid = 22189403 | pmc = 3311884 | doi = 10.1098/rspb.2011.2091 }}</ref> Capsaicin synthesis in chilies places a strain on their water resources.<ref>{{Cite journal | vauthors = Ruiz-Lau N, Medina-Lara F, Minero-García Y, Zamudio-Moreno E, Guzmán-Antonio A, Echevarría-Machado I, Martínez-Estévez M |date=2011-03-01 |title=Water Deficit Affects the Accumulation of Capsaicinoids in Fruits of Capsicum chinense Jacq. |url=https://journals.ashs.org/hortsci/view/journals/hortsci/46/3/article-p487.xml |journal=HortScience |language=en-US |volume=46 |issue=3 |pages=487–492 |doi=10.21273/HORTSCI.46.3.487 |s2cid=86280396 |issn=0018-5345|doi-access=free }}</ref> This directly affects their fitness, as it has been observed that standard concentration of capsaicin of peppers in high moisture environments in the seeds and [[pericarp]]s of the peppers reduced the seeds production by 50%.<ref>{{cite journal | vauthors = Mahmood T, Rana RM, Ahmar S, Saeed S, Gulzar A, Khan MA, Wattoo FM, Wang X, Branca F, Mora-Poblete F, Mafra GS, Du X | title = Effect of Drought Stress on Capsaicin and Antioxidant Contents in Pepper Genotypes at Reproductive Stage | journal = Plants | volume = 10 | issue = 7 | pages = 1286 | date = June 2021 | pmid = 34202853 | pmc = 8309139 | doi = 10.3390/plants10071286 | doi-access = free | bibcode = 2021Plnts..10.1286M }}</ref>