Re: Hybrids

David Purks (telenet!twinkie!
Tue, 21 Jun 1994 10:05:00 -0400 (EDT)

> Food for thought... RE: your point about Sarracenia being all one
> species... ARE all sarrs a single species? I think not, but if I'm not
> mistaken, ALL sarrs are interfertile, and in many cases where their
> microranges overlap, natural hybrids occur... hybrid swarms of
> rubra/leuco/etc in Fla. panhandle are another interesting occurrence...
> I think it would be impossible to ever find a "pure species" in this area
> (this subject has been covered to some extent in the literature, I think)
> -philip thomas
> On Thu, 16 Jun 1994, Terry Bertozzi - 229112 wrote:
> > >
> > > What makes a "pure species?"
> >
> > As far as I am concerned (from a zoological point of view) Separate species
> > cannot interbreed to form viable offspring, that is they produce sterile
> > hybrids. Is this different in the botanical world, because Sarracenia
> > does not fit this criteria? Are we dealing with variants of one species?

Many "species" are quite capable (genetically) of interbreeding but
don't because of other factors. Once those impediments are removed,
hybrids occur quite naturally. This is often the case where two
species are separated by a geographical barrier, such as a large body
of water or mountain range.

In the case of Sarracenia (or any other cp for that matter), the limited
environment that they're capable of flourishing in would tend to isolate
groups of plants. An advantageous mutation in a particular bog (giving
an individual plant some minor advantage over its neighbors) will tend
to increase in numbers. In time, one or more mutations could tend to make
a group of plants in one bog look "significantly" different from those
in another bog so that they could be classified as separate species.

As for the thread that was going on about mutations...there are two
basic types of mutations possible: meiotic mutations (involving the
number of chromosomes present in divided cells) and replication
mutations. Replication mutations may be anything from a singe base
pair incorrectly duplicated to wholesale additions or deletions of
genetic material to a chromosome (for example via plasmids or viral
action). Most mutations are either so small that they produce no
visible change in the child, or are so massive that the resulting
individual is unable to survive to reproduce or is infertile. It is
very rare for any individual mutation to produce an individual which
is significantly different from the parent, gives the individual
some advantage over the parent (without advantage, there's less of a
chance that the mutation will spread through the population), and is
fertile. (I apologize if this information is condensed too much or
if I've forgotten any significant information - it's been several
years since I've taken genetics and the memory is not what it used
to be!)