Editing Karyotype (section)

=== Number of chromosomes in a set ===

A spectacular example of variability between closely related species is the [[muntjac]], which was investigated by [[Kurt Benirschke]] and [[Doris Wurster]]. The diploid number of the Chinese muntjac, ''[[Muntiacus reevesi]]'', was found to be 46, all [[telocentric]]. When they looked at the karyotype of the closely related Indian muntjac, ''[[Muntiacus muntjak]]'', they were astonished to find it had female = 6, male = 7 chromosomes.<ref>{{cite journal |vauthors=Wurster DH, Benirschke K |title=Indian muntjac, ''Muntiacus muntjak'': a deer with a low diploid chromosome number |journal=Science |volume=168 |issue=3937 |pages=1364–6 |date=June 1970 |pmid=5444269 |doi=10.1126/science.168.3937.1364|bibcode = 1970Sci...168.1364W |s2cid=45371297 }}</ref>

{{blockquote|They simply could not believe what they saw ... They kept quiet for two or three years because they thought something was wrong with their tissue culture ... But when they obtained a couple more specimens they confirmed [their findings].|Hsu p. 73-4<ref name="Hsu"/>}}

The number of chromosomes in the karyotype between (relatively) unrelated species is hugely variable. The low record is held by the [[nematode]] ''[[Parascaris univalens]]'', where the [[haploid]] n = 1; and an ant: ''[[Myrmecia pilosula]]''.<ref>{{cite journal|author1=Crosland M.W.J.  |author2=Crozier, R.H.|year=1986|title=''Myrmecia pilosula'', an ant with only one pair of chromosomes|journal=Science|volume=231|pages=1278|doi=10.1126/science.231.4743.1278|pmid=17839565|issue=4743|bibcode=1986Sci...231.1278C|s2cid=25465053}}</ref> The high record would be somewhere amongst the [[fern]]s, with the adder's tongue fern ''[[Ophioglossum]]'' ahead with an average of 1262 chromosomes.<ref>{{cite journal |author=Khandelwal S. |title=Chromosome evolution in the genus Ophioglossum L |journal=Botanical Journal of the Linnean Society |volume=102 |pages=205–217 |year=1990 |doi=10.1111/j.1095-8339.1990.tb01876.x |issue=3 }}</ref> Top score for animals might be the [[shortnose sturgeon]] ''[[Acipenser brevirostrum]]'' at 372 chromosomes.<ref name=Kim2005>{{cite journal |first=D.S. |last=Kim |author2=Nam, Y.K. |author3=Noh, J.K. |author4=Park, C.H. |author5=Chapman, F.A. | year = 2005 | title = Karyotype of North American shortnose sturgeon ''Acipenser brevirostrum'' with the highest chromosome number in the Acipenseriformes | journal = Ichthyological Research | volume = 52 | issue = 1 | pages = 94–97 | doi = 10.1007/s10228-004-0257-z|bibcode=2005IchtR..52...94K |s2cid=20126376 }}</ref> The existence of supernumerary or [[B chromosomes]] means that chromosome number can vary even within one interbreeding population; and [[aneuploid]]s are another example, though in this case they would not be regarded as normal members of the population.