:''Paternal leakage redirects here''
In genetics paternal mtDNA transmission
and paternal mtDNA inheritance
refer to the incidence of paternal mitochondrial DNA (mtDNA) being passed on to offspring Paternal mtDNA inheritance
is observed in a small number
of species but in the vast majority
mtDNA is believed to be passed unchanged
[The mtDNA is passed from mother to offspring unchanged except for the occasional genetic mutation the rate of which is unknown but is sometimes estimated as once every 600 generations (see Mitochondrial DNA Mutation Rates)]
from a mother to her offspring This belief
is central to mtDNA genealogical DNA testing and to the theory
of mitochondrial Eve
However there is evidence that in sexual reproduction the tail
of the sperm does enter the egg and thus paternal leakage
The phenomenon of paternal leakage
was summed up in the 1996 study Misconceptions about mitochondria and mammalian fertilization: Implications for theories on human evolution
[ Misconceptions about mitochondria and mammalian fertilization: Implications for theories on human evolution by Friderun Ankel-Simons and Jim M. Cummins 1996]
The mixing of maternal and paternal mtDNA has been found in humans and chimpanzees
[ Linkage Disequilibrium and Recombination in Hominid Mitochondrial DNA (PDF) by Philip Awadalla Adam Eyre-Walker and John Maynard Smith (view abstract) Science 24 December 1999: Vol 286] [ mtDNA Shows Signs of Paternal Influence by Evelyn Strauss Science 24 December 1999: Vol 286 no. 5449 p. 2436; DOI: 101126/science28654492436a]
However there is great debate about the implications of these results
Many sources notably companies that sell genealogical DNA tests state that paternal mtDNA is never transmitted to offspring However a mounting number
of studies show that paternal mtDNA can be inherited Responses to this evidence involves saying that so little paternal mtDNA is transmitted as to be negligable ("Some researchers argue that a fragment of the father's mtDNA is in fact
passed on, though it represents much less than 1 percent of the total"
[ NOVA Teachers: America's Stone Age Age Classroom Activity]
) or saying that paternal mtDNA is so rarely transmitted as to be negligable ("Nevertheless studies have established that paternal mtDNA is so rarely transmitted to offspring that mtDNA analyses remain valid"
[evolutionary biologist Andrew Merriwether quoted in Debunking a myth about sperm's DNA (research indicates paternal mitochondrial DNA does enter fertilized egg) by John Travis Science News 1/25/1997]
On the other
side of the issue are people who want
to dismiss maternal mtDNA inheritance
completely A surname project tutorial states "A male will rarely get his father's mtDNA So far this has been observed one time
in the past 20 years of research"
[ Jordan Surname DNA Project: Tutorial]
This single instance is cited as evidence that the whole field of mitochondrial genetics is invalid
In either case these phenomena throw doubt on the theory
that all mtDNA can be traced back to a single female This theory
of mitochondrial Eve
which aims to trace all humans to "a woman living in sub-Saharan Africa about 200000 years ago"
[ African Eve Theory Smashed by Computer by Marvin Lubenow July 1992]
allows no room
for the inheritance
of paternal mtDNA
Paternal mtDNA inheritance
in animals varies For example in Mytilidae mussels paternal mtDNA "is transmitted through the sperm and establishes itself only in the male gonad"
[[http://wwwncbinlmnihgov/entrez/queryfcgi?cmd=Retrieve&db=PubMed&list_uids=11280005&dopt=AbstractThe exceptional mitochondrial DNA system of the mussel family Mytilidae] by E. Zouros December 2000] [ The Fate of Paternal Mitochondrial DNA in Developing Female Mussels Mytilus edulis: Implications for the Mechanism of Doubly Uniparental Inheritance of Mitochondrial DNA by Brent Sutherland Donald Stewart Ellen R. Kenchington and Eleftherios Zouros] [ Male and Female Mitochondrial DNA Lineages in the Blue Mussel (Mytilus edulis) Species Group by Donald T. Stewart Carlos Saavedra Rebecca R. Stanwood Amy 0. Ball and Eleftherios Zouros]
In testing 172 sheep
"the mitochondrial DNA from three lambs in two half-sib families were found to show paternal inheritance"
[ Further evidence for paternal inheritance of mitochondrial DNA in the sheep (Ovis aries) by X. Zhao1 N. Li, W. Guo1 X. Hu, Z. Liu G. Gong A. Wang1 J. Feng and C. Wu1 Nature October 2004 Volume 93, Number 4, Pages 399-403]
References and notes