T
Tim Tyler
Guest
Matt Ridley's take on the definition of species selection:
``Species selection is a higher level analog of normal
natural selection within a population. Species selection
means, other things being equal, that those kinds of species
that have lower extinction and higher speciation rates will
tend to increase in frequency over evolutionary time.''
- Evolution (the textbook), Matt Ridley, 3rd edition, p.
665.
As far as I can see, this is the perfectly natural and
conventional definition of species selection - one based on
the actual differential reproductive success of species.
Note that there is no mention at all of whether the
differential reproductive rates could also be explained in
terms of selection at a lower level.
Ridley uses a similar definiton for group selection - on
p.303 - citing Wade's Trifolium experiments as an example of
group selection under laboratory conditions.
This used selection for low fecundity - a fairly clear
example of a trait where the property of the group is the
additive result of individual properties.
It seems to me that those who favour other definitions of
group and species selection - involving whether the effect
could also be explained at a lower level - still have
textbook authors to convince - in addition to me and a
number of other sceptics.
--
__________
|im |yler http://timtyler.org/ [email protected] Remove
lock to reply.
``Species selection is a higher level analog of normal
natural selection within a population. Species selection
means, other things being equal, that those kinds of species
that have lower extinction and higher speciation rates will
tend to increase in frequency over evolutionary time.''
- Evolution (the textbook), Matt Ridley, 3rd edition, p.
665.
As far as I can see, this is the perfectly natural and
conventional definition of species selection - one based on
the actual differential reproductive success of species.
Note that there is no mention at all of whether the
differential reproductive rates could also be explained in
terms of selection at a lower level.
Ridley uses a similar definiton for group selection - on
p.303 - citing Wade's Trifolium experiments as an example of
group selection under laboratory conditions.
This used selection for low fecundity - a fairly clear
example of a trait where the property of the group is the
additive result of individual properties.
It seems to me that those who favour other definitions of
group and species selection - involving whether the effect
could also be explained at a lower level - still have
textbook authors to convince - in addition to me and a
number of other sceptics.
--
__________
|im |yler http://timtyler.org/ [email protected] Remove
lock to reply.