Editing Periodical cicadas (section)

==Taxonomy==
=== Phylogeny ===
''Magicicada'' is a member of the cicada [[Tribe (biology)|tribe]] [[Lamotialnini]], which is distributed globally aside from [[South America]]. Despite ''Magicicada'' being only found in eastern [[North America]], its closest relatives are thought to be the genera ''[[Tryella]]'' and ''[[Aleeta]]'' from [[Australia]], with ''Magicicada'' being [[Sister group|sister]] to the [[clade]] containing ''Tryella'' and ''Aleeta''.<ref>{{Cite journal|last1=Marshall|first1=David C.|last2=Moulds|first2=Max|last3=Hill|first3=Kathy B. R.|last4=Price|first4=Benjamin W.|last5=Wade|first5=Elizabeth J.|last6=Owen|first6=Christopher L.|last7=Goemans|first7=Geert|last8=Marathe|first8=Kiran|last9=Sarkar|first9=Vivek|last10=Cooley|first10=John R.|last11=Sanborn|first11=Allen F.|date=2018-05-28|title=A molecular phylogeny of the cicadas (Hemiptera: Cicadidae) with a review of tribe and subfamily classification|url=https://www.mapress.com/j/zt/article/view/zootaxa.4424.1.1|journal=Zootaxa|language=en|volume=4424|issue=1|pages=1–64|doi=10.11646/zootaxa.4424.1.1|pmid=30313477|s2cid=52976455|issn=1175-5334}}</ref> Within the [[Americas]], its closest relative is thought to be the genus ''[[Chrysolasia]]'' from [[Guatemala]].<ref>{{Cite web|last=says|first=Dave|date=2019-01-10|title=Chrysolasia guatemalena (Distant, 1883)|url=https://www.cicadamania.com/cicadas/chrysolasia-guatemalena-distant-1883/|access-date=2021-05-15|website=Cicada Mania|language=en}}</ref>

=== Species ===
Seven recognized species are placed within ''Magicicada''—three 17-year species and four 13-year species. These seven species are also sometimes grouped differently into three subgroups, the so-called [[Decim periodical cicadas|Decim species group]], [[Cassini periodical cicadas|Cassini species group]], and Decula species group, reflecting strong similarities of each 17-year species with one or more species with a 13-year cycle.<ref name=ngspecies>{{cite web|title=''Magicicada'' species|url=http://www.magicicada.org/about/species_pages/species.php|publisher=National Geographic Society|access-date=12 June 2011|archive-date=February 26, 2017|archive-url=https://web.archive.org/web/20170226165547/http://www.magicicada.org/about/species_pages/species.php|url-status=dead}}</ref>
{|class="wikitable collapsible"
|-
! colspan="4"|17-year cycle
! rowspan="2"|Species<br/>group
! colspan="4"|13-year cycle
|-
! Image
! Scientific name
! Common Name
! Distribution
! Image
! Scientific name
! Common Name
! Distribution
|-
|rowspan="2"|[[File:2013 05-23 IMG 9586 (3).jpg|120px]]
|rowspan="2"|''[[Magicicada septendecim|M.&nbsp;septendecim]]''<br/><small>([[Carl Linnaeus|Linnaeus]], 1758)</small>
|rowspan="2"|17-year locust, <br/>Pharaoh cicada
|rowspan="2"|Canada,<br/>United States
!rowspan="2"|Decim
|[[File:Magicicada_tredecim.jpg|120px]]
|''[[Magicicada tredecim|M.&nbsp;tredecim]]''<br/><small>(Walsh & Riley, 1868)</small>
|
|Southeastern<br/>United States
|-
|
|''[[Magicicada neotredecim|M.&nbsp;neotredecim]]''<br/><small>Marshall & Cooley, 2000<!-- Do not add parentheses. --></small>
|
|United States
|-
|[[File:Magicicada cassini (17-year periodical cicada) (Flint Ridge, Ohio, USA) (27294270804).jpg|120px]]
|''[[Magicicada cassinii|M.&nbsp;cassini]]'' <ref name="Marshall 2022">{{cite journal |last1=Marshall |first1=David C. |title=On the spelling of the name of Cassin's 17-Year Cicada, Magicicada cassini (Fisher, 1852) (Hemiptera: Cicadidae) |journal=Zootaxa |date=8 April 2022 |volume=5125 |issue=2 |pages=241–245 |doi=10.11646/zootaxa.5125.2.8 |pmid=36101217 |s2cid=248041307 |doi-access=free }} [open access]</ref><br/><small>(Fisher, 1852)</small>
|17-year cicada, <br/>dwarf periodical cicada
|United States
!Cassini
|[[File:Magicicada tredecassini NC XIX male dorsal trim.jpg|120px]]
|''[[Magicicada tredecassini|M.&nbsp;tredecassini]]''<br/><small>Alexander & Moore, 1962</small>
|
|United States
|-
|[[File:Magicicada septendecula male (Brood IX) - journal.pone.0000892.g003C.png|120px]]
|''[[Magicicada septendecula|M.&nbsp;septendecula]]''<br/><small>Alexander & Moore, 1962<!-- Do not add parentheses. --></small>
|
| United States
!Decula
|[[File:Magicicada tredecula Brood XIX 11.US.IL.DAS.jpg|120px]]
|''[[Magicicada tredecula|M.&nbsp;tredecula]]''<br/><small>Alexander & Moore, 1962</small>
|
| United States
|-
|}

===Evolution and speciation===
{{See also|Allochronic speciation}}
Not only are the periodical cicada life cycles curious for their use of the prime numbers 13 or 17, but their evolution is also intricately tied to one- and four-year changes in their life cycles.<ref name="Cox, R. T., and C. E. Carlton 1988 183–193" /><ref name="Cox, R. T., and C. E. Carlton 1991 63–74" /> One-year changes are less common than four-year changes and are probably tied to variation in local climatic conditions. Four-year early and late emergences are common and involve a much larger proportion of the population than one-year changes. The different species are well-understood to have originated from a process of [[allochronic speciation]],<ref>Multiple sources:
* {{cite journal|author=Rebecca S. Taylor and Vicki L. Friesen|year=2017|title=The role of allochrony in speciation|journal=Molecular Ecology|volume=26|issue=13|pages=3330–3342|doi=10.1111/mec.14126|pmid=28370658|bibcode=2017MolEc..26.3330T |doi-access=free|s2cid=46852358}}
* {{cite journal|first1=D. C.|last1=Marshall|first2=J. R.|last2=Cooley|year=2000|title=Reproductive character displacement and speciation in periodical cicadas, with description of new species, 13-year Magicicada neotredecem|journal=Evolution|volume=54|issue=4|pages=1313–1325|doi=10.1111/j.0014-3820.2000.tb00564.x|pmid=11005298|doi-access=free|s2cid=28276015|hdl=2027.42/73691|hdl-access=free}}
* {{cite journal|first1=C.|last1=Simon|author1-link=Chris Simon (biologist)|first2=J.|last2=Tang|first3=S.|last3=Dalwadi|first4=G.|last4=Staley|first5=J.|last5=Deniega|first6=T. R.|last6=Unnasch|year=2000|title=Genetic evidence for assortative mating between 13-year cicadas and sympatric '17-year cicadas with 13-year life cycles' provides support for allochronic speciation|url=|journal=Evolution|volume=54|issue=4|pages=1326–1336|doi=10.1111/j.0014-3820.2000.tb00565.x|pmid=11005299|doi-access=free|s2cid=19105047}}</ref><ref name="Sota Yamamoto 2013">{{cite journal|first1=Teiji|last1=Sota|first2=Satoshi|last2=Yamamoto|first3=John R.|last3=Cooley|first4=Kathy B. R.|last4=Hill|first5=Chris |last5=Simon|author5-link=Chris Simon (biologist)|first6=Jin|last6=Yoshimura|date=23 April 2013|title=Independent divergence of 13- and 17-y life cycles among three periodical cicada lineages|journal=[[Proceedings of the National Academy of Sciences of the United States of America]]|volume=110|issue=17|pages=6919–6924|bibcode=2013PNAS..110.6919S|doi=10.1073/pnas.1220060110|pmc=3637745|pmid=23509294|doi-access=free}}</ref> in which species subpopulations that are isolated from one another in time eventually become [[reproductive isolation|reproductively isolated]] as well.

Research suggests that in extant periodical cicadas, the 13- and 17-year life cycles evolved at least eight different times in the last 4 million years and that different species with identical life cycles developed their overlapping geographic distribution by synchronizing their life cycles to the existing dominant populations.<ref name="Sota Yamamoto 2013"/> The same study estimates that the Decim species group split from the common ancestor of the Decula plus Cassini species groups around 4&nbsp;million years ago (Mya). At around 2.5&nbsp;Mya, the Cassini and Decula groups split from each other.

The Sota ''et al.'' (2013) paper also calculates that the first separation of extant 13-year cicadas from 17-year cicadas took place in the Decim group about 530,000 years ago when the southern ''M.&nbsp;tredecim'' split from the northern ''M.&nbsp;septendecim''. The second noteworthy event took place about 320,000''&nbsp;''years ago with the split of the western Cassini group from its conspecifics to the east. The Decim and the Decula clades experienced similar western splits, but these are estimated to have taken place 270,000 and 230,000''&nbsp;''years ago, respectively. The 13- and 17-year splits in Cassini and Decula took place after these events.

The 17-year cicadas largely occupy formerly glaciated territory, and as a result their phylogeographic relationships reflect the effects of repeated contraction into glacial refugia (small islands of suitable habitat) and subsequent re-expansion during multiple interglacial periods. In each species group, Decim, Cassini, and Decula, the signature of the glacial periods is manifested in three phylogeographic genetic subdivisions: one subgroup east of the Appalachians, one midwestern, and one on the far western edge of their range.

The Sota ''et al.'' data suggest that the founders of the southern 13-year cicada populations originated from the Decim group. These were later joined by Cassini originating from the western Cassini clade and Decula originating from eastern, middle, and western Decula clades. As Cassini and Decula invaded the south, they became synchronized with the resident ''M.&nbsp;tredecim''. These Cassini and Decula are known as ''M.&nbsp;tredecassini'' and ''M.&nbsp;tredecula''. More data is needed to lend support to this hypothesis and others hypotheses related to more recent 13- and 17-year splits involving ''M.&nbsp;neotredecim'' and ''M.&nbsp;tredecim''.