Richard Forrest wrote:

Ymir wrote:

In article <1164361532.760007.268450@h54g2000cwb.googlegroups.com>,
"SJAB1958" <balfres@hotmail.com> wrote:

1. Would you agree that the donkey and the horse share a common
ancestor?

All organisms share a common ancestor. In the case of horses and donkeys
that common ancestor was relatively recent.

2. Would you agree that the resulting offspring cannot breed amongst
themselves?

In the vast majority of cases, yes. There have been rare cases where
mules have successfully mated with horses, donkeys, or hinnies, but I
have no idea whether the offspring in these particular cases were
themselves fertile.

3. Would you agree that this is a result of macroevolution?

No. This is hybridisation, not evolution. (well, unless you are
referring to the fact that the infertility results from low chromosomal
compatability between horses and donkeys which is, of course, the result
of their evolutionary divergence from their most recent common ancestor).

Explain your answer to the last question if you answered in the
negative.

The creationist definition of 'macroevolution' usually involves the
generation of new species until it is pointed out to them that this has
been observed on many occasions in which case they switch from species
to some ill-defined notion of 'kind' (which presumably refers to
something above the species level, but whether this is genus, phylum, or
domain is utterly beyond me ‹ do mules and chrysanthema constitute a
single kind?).

Since organisms are generally viewed as belonging to the same species
(in the case of sexually reproducing organisms at any rate) if they can
interbreed to produce fertile offspring, infertile hybrids don't
constitute a species at all.

André

--
use rot thirteen to email
ntvfnnx (at) tznvy.pbz

Hybrodisation is far more common in nature than was once thought, and
can be a mechanism in speciation. We tend to focus rather too closely
on mammals, in which hybridisation is rare, and rarely produces viable
offspring. However, it is common in some fish populuations, and wildly
profligate in plants, frequently leading to new and biologically
distinct species.

My first reaction was to cite the hybridization of corn and remembered
that they are hybriid varieties, not species.

We who are interested in science, but live outside the science arena,
have a challenge with the scientific versus pedestrian use of terms.

On 24 Nov 2006 06:33:22 -0800, "Ron O" <rokimoto@cox.net> enriched
this group when s/he wrote:

Ye Old One wrote:

On 24 Nov 2006 01:45:32 -0800, "SJAB1958" <balfres@hotmail.com>
enriched this group when s/he wrote:

1. Would you agree that the donkey and the horse share a common
ancestor?

They must do, they are close enough to each other that they can breed.

Oh darn, then why are chimps and humans genetically more closely
related than horses and donkeys for the nuclear DNA sequences that we
have compared? The intelligent designer must not be very consistent on
this speciation thing.

There is no evidence for an "intelligent designer".

As for human/chimp hybrodisation, I'm not aware of any research done
into that field.

2. Would you agree that the resulting offspring cannot breed amongst
themselves?

True.

Well the backcross to either species sometimes works.

Very rare.

The equid
chromosomes are so scrambled that the rare offspring of mules bred back
to horses usually have the horse chromosomal compliment. It is a
pretty rare event for the mule to get all the horse chromosomes in the
same gamete for the back cross to work.

3. Would you agree that this is a result of macroevolution?

Yes.

Speciation is macroevolution.

The horse and donkey are species.

The definition is evolution above the
species level. Within species evolution would be considered to be
microevolution.

Is it?

--
Bob.