[Taxacom] Fwd: Fwd: Inbreeding, health, and evolution

Michael Heads m.j.heads at gmail.com
Wed Feb 12 19:10:39 CST 2014


Hi Ken,

No-one argues that the founder effect is real. But many geneticists argue
that it will not lead to speciation. Mayr brought it in on the basis of
biogeography, not genetics, but it is not actually needed in biogeography
either.

Michael


On Thu, Feb 13, 2014 at 1:56 PM, Ken Kinman <kinman at hotmail.com> wrote:

> Hi Michael,
>
>                The real debate isn't whether the founder effect is real or
> not.  The question is how common or uncommon it is.  I suspect it may be
> less common than Mayr might have thought, but more common than his critics
> realize.  However, common or uncommon it might be, it is still a good
> example of how inbreeding is not always bad.
>                          ----------------Ken Kinman
>
>
> ----------------------------------------------------------------------------------------------------
> > Date: Wed, 12 Feb 2014 18:22:08 +1300
> > From: m.j.heads at gmail.com
> > To: Taxacom at mailman.nhm.ku.edu
> > Subject: [Taxacom] Fwd: Inbreeding, health, and evolution
>
> >
> > Hi Ken,
> >
> > You support founder effect speciation, which was a key premise of modern
> > synthesis biogeography. But here is what some geneticists have said about
> > it (fom my 2012 book):
> >
> > While many biogeographers have accepted the argument [Mayr on founder
> > effect and 'genetic revolution'] from genetics, geneticists themselves
> have
> > been less convinced. Tokeshi (1999) argued that the genetic founder
> effect does
> > not seem to be an effective means of speciation and Nei (2002) cited 'one
> > of the most important findings in evolutionary biology in recent years:
> > that speciation by the founder principle may not be very common after
> all'.
> > Orr (2005) wrote that despite the early popularity of the idea, 'it is
> > difficult to point to unambiguous evidence for founder effect speciation,
> > and the idea has grown controversial'. The experiments of Moya et al.
> > (1995) failed to corroborate predictions of founder effect speciation and
> > subsequent studies have also found no evidence for it (Rundle et al.,
> 1998,
> > Mooers et al., 1999, McKinnon and Rundle, 2002, Rundle, 2003). Crow
> (2008)
> > called the idea of genetic revolution 'vague and misguided' (see also
> Crow,
> > 2009). Even in birds, founder effects 'may be unnecessary' (Grant, 2001,
> > cf. Walsh et al., 2005). The passerine *Zosterops* is often cited as the
>
> > classic case of a taxon that has evolved by founder speciation (Mayr and
> > Diamond, 2001), yet a detailed study of clades in the south-west Pacific
> > concluded that the focus on founder effects in this group 'has been
> > overemphasized' (Clegg et al., 2002).
> > Florin (2001) described how 'The vicariance model of allopatric
> > speciation has been repeatedly confirmed empirically, while peripatric
> > [founder effect] speciation has suffered severe criticism for being both
> > implausible and empirically unsupported'. In her own studies on flies she
> > found 'no support for speciation through founder effects'. In recent
> years
> > the debate has heated up and advocates of dispersal theory have found it
> > necessary to publish an article stressing 'The reality and importance of
> > founder speciation in evolution' (Templeton, 2008). This was a reply to
> > Coyne and Orr's (2004: 401) conclusion that 'there is little evidence for
> > founder effect speciation'. Coyne (1994) wrote that the idea 'has
> infected
> > evolutionary biology with a plague of problematic work'.
> >
> > Michael
> >
> >
> >
> > On Wed, Feb 12, 2014 at 3:41 PM, Ken Kinman <kinman at hotmail.com> wrote:
> >
> > > Dear All,
> > > The whole debate over Marius the giraffe, got me thinking again
> > > about something I hadn't looked at in many years. Although the risks of
> > > inbreeding are real, especially when it is repeated sequentially over
> > > several generations, have those risks been overstated (especially in
> the
> > > first or second generation)? If the risk increases from 2% to 4% for
> first
> > > cousins mating, that is an increase of 100%. Yikes!!!??? But is 4%
> versus
> > > 2% something to getting overly excited about, especially in a non-human
> > > species like giraffes?
> > > If Marius the giraffe posed an increased risk of health problems
> > > in his progeny that was 4% versus 2%, does that even justify
> eliminating
> > > him from breeding (much less killing him outright?). Geneticists might
> say
> > > that this is a 100% increase in risk, but are they statistically
> > > exaggerating the risks (not only to other researchers and the public at
> > > large, but perhaps in their own minds as well)?
> > > And as those of us who study evolution of species, do we too often
> > > overlook how often species arose from the "founder effect"? Many have
> no
> > > doubt resulted from just a few individuals (or even just a single
> pregnant
> > > female) being isolated on an island or isolated area. And in spite of
> the
> > > obvious inbreeding, a new species is created and can even thrive.
> Why???
> > > Because inbreeding can not only increase the frequency of bad genes,
> but
> > > sometimes can increase the frequency of extremely beneficial genes as
> well.
> > > If we are to be open-minded scientists, shouldn't we be looking much
> > > harder at such potential benefits, and that the religious prohibitions
> > > against matings between third, second or even first cousins, may apply
> in
> > > certain cases, but not the extreme risk it is so often made out to be.
> In
> > > many cases, the risk may overall be neither particularly negative or
> > > positive. In which case, the preoccupation of geneticists relating to
> > > Marius and giraffe populations, may be overly exaggerated. We will
> never
> > > know in the case of Marius since they prejudged this healthy
> individual as
> > > a genetic risk (perhaps ultimately based on statistics which were
> > > exaggerated by some scientists, even though it may have not been
> > > exaggerated intentionally). Below is a weblink to just one single
> > > discussion of such unresolved scientific questions.
> > > ----------------------------Ken Kinman
> > >
> > >
> http://theconversation.com/birth-defect-risk-for-children-of-first-cousins-is-overstated-15809
> > >
> > >
> > >
> > > _______________________________________________
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> > > The Taxacom Archive back to 1992 may be searched at:
> > > http://taxacom.markmail.org
> > >
> > > Celebrating 27 years of Taxacom in 2014.
> > >
> >
> >
> >
> > --
> > Dunedin, New Zealand.
> >
> > My recent books:
> >
> > *Molecular panbiogeography of the tropics.* 2012. University of
> California
> > Press, Berkeley. www.ucpress.edu/book.php?isbn=9780520271968
> >
> > *Biogeography of Australasia: A molecular analysis*. 2014. Cambridge
> > University Press, Cambridge. www.cambridge.org/9781107041028
>
> > _______________________________________________
> > Taxacom Mailing List
> > Taxacom at mailman.nhm.ku.edu
> > http://mailman.nhm.ku.edu/mailman/listinfo/taxacom
> > The Taxacom Archive back to 1992 may be searched at:
> http://taxacom.markmail.org
> >
> > Celebrating 27 years of Taxacom in 2014.
>



-- 
Dunedin, New Zealand.

My recent books:

*Molecular panbiogeography of the tropics.* 2012. University of California
Press, Berkeley. www.ucpress.edu/book.php?isbn=9780520271968

*Biogeography of Australasia:  A molecular analysis*. 2014. Cambridge
University Press, Cambridge. www.cambridge.org/9781107041028



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