hermaphroditism-dioecy and the molecular clock

Mircea Podar podar at utsw.swmed.edu
Fri Jan 3 15:08:02 EST 1997

When using molecular data (rRNA or other) in determining the evolutionary
distance between say two closely related species (related as defined by
"clasical" analysis), one has to be quite confident that the rate of
molecular evolution is similar between the two. This is usually (or should
be) the case. However, what would happen if one would compare two species
of invertebrates that are morphologically related but have different
reproductive strategies : one of them is hermaphroditic and reproduces
mostly by self-fertilization and the other has separate sexes. The
population size I think is an important factor, but for sake of simplicity
suppose both species have large populations and there is no physical
barrier to limit the dispersal if individuals. It appears to me that the
molecular clock of the two species would be quite different and the
distance between them would be tricky to deduce based on sequence data (at
least using nuclear genes). On the other hand, since the transmision of the
mitochondrial genes is uniparental, does this mean that the molecular clock
for the mitochondrial genes is similar between a hermaphroditic and a
dioeic species? 
I would appreciate any comment on the above problem, or some references.

Mircea Podar
podar at utsw.swmed.edu

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