O. Verneau et al., DETERMINING AND DATING RECENT RODENT SPECIATION EVENTS BY USING L1 (LINE-1) RETROTRANSPOSONS, Proceedings of the National Academy of Sciences of the United Statesof America, 95(19), 1998, pp. 11284-11289
Phylogenies based on the inheritance of shared derived characters will
be ambiguous when the shared characters are not the result of common
ancestry. Such characters are called homoplasies. Phylogenetic analysi
s also can be problematic if the characters have not changed sufficien
tly, as might be the case for rapid or recent speciations. The latter
are of particular interest because evolutionary processes may be more
accessible the more recent the speciation. The repeated DNA subfamilie
s generated by the mammalian L1 (LINE-1) retrotransposon are apparentl
y homoplasy-freee phylogenetic characters. L1 retrotransposons are tra
nsmitted only by inheritance and rapidly generate novel variants that
produce distinct subfamilies of mostly defective copies, which then ''
age'' as they diverge, Here we show that the L1 character can both res
olve and date recent speciation events within the large group of very
closely related rats known as Rattus sensu stricto. This lineage arose
5-6 million years ago (Mya) and subsequently underwent two episodes o
f speciation: an intense one, approximate to 2.7 Mya, produced at leas
t five lineages in <0.3 My; a second began approximate to 1.2 Mya and
may still be continuing.