Bj. Saville et al., MTDNA RECOMBINATION IN A NATURAL-POPULATION, Proceedings of the National Academy of Sciences of the United Statesof America, 95(3), 1998, pp. 1331-1335
Variation in mtDNA has been used extensively to draw inferences in phy
logenetics and population biology, In the majority of eukaryotes inves
tigated, transmission of mtDNA is uniparental and clonal, with genotyp
ic diversity arising from mutation alone. In other eukaryotes, the tra
nsmission of mtDNA is biparental or primarily uniparental with the pos
sibility of ''leakage'' from the minority parent, In these cases, hete
roplasmy carries the potential for recombination between mtDNAs of dif
ferent descent. In fungi, such mtDNA recombination has long been docum
ented but only in laboratory experiments and only under conditions in
which heteroplasmy is ensured, Despite this experimental evidence, mtD
NA recombination has not been to our knowledge documented in a natural
population, Because evidence from natural populations is prerequisite
to understanding the evolutionary impact of mtDNA recombination, we i
nvestigated the possibility of mtDNA recombination in an organism with
the demonstrated potential for heteroplasmy in laboratory matings, Us
ing nucleotide sequence data, we report here that the genotypic struct
ure of mtDNA in a natural population of the basidiomycete fungus Armil
laria gallica is inconsistent with purely clonal mtDNA evolution and i
s fully consistent with mtDNA recombination.