My impression was that the whole family Viverridae (like the Civet) are
half-way between dogs and cats. of course not the offspring of a dog and
cat, but phylogenetically the same idea ?
In article <7o7aun$s3b$1 at nnrp1.deja.com>, *Hemidactylus*
<hemidactylus at my-deja.com> wrote:
> In article <7nvcsd$rev at dfw-ixnews11.ix.netcom.com>,
> "BlaDe" <icontrol at ix.netcom.com> wrote:
> > Why cant you mix a dogs eggs and a cats sperm to get a wierd type of animal?
>> They are not only separate species, but they belong to different carnivore
> families. Cats are felids and dogs are canids. I don't know the exact number,
> but there is a large expanse of time separating the dogs and cats.
>> Interbreeding is an issue central to evolutionary concepts of species. A so
> called "good species" is something which is reproductively isolated from
> closely related populations. This concept does have its rough edges. There
> are instances of hybridization between groups that are considered members of
> separate species, but in general, this a handy rule.
>> A related issue here is reproductive isolating mechanisms (RIM's). There are
> several types of isolating mechanisms which serve as a block against breeding
> between two individuals from different populations. The isolation might be
> behavioral, seasonal, or even genetic. With strong enough isolation comes
>> Two individuals might have genetic incompatibilities ranging from having
> different numbers of chromosomes, having genes (from mother and father) which
> do not function together well, or having an incomplete set of genes for
> important developmental steps. There are other considerations. My treatment
> is painfully inadequate.
>> You might find answers to evolutionary level questions in evolutionary
> biology texts by either Futuyma or Minkoff.
> > Same things with humans. Does the sperm die immediatley when hitting the
> > egg? Something must be happening.
>> You might find answers to these questions in developmental biology texts (eg
> Scott Gilbert's _Developmental Biology_). There is lots of work being done on
> both sea urchin and mouse fertilization. The details are fairly complex.
> There could be species specificity "checkpoints" along the way from egg and
> sperm being attracted all the way through fertilization. This helps ensure
> that there isn't wasteful development of inviable hybrid embryos. These
> mechanisms aren't perfect though, I'd imagine.
>> The mechanisms that pertain to a neuro perspective would probably be the
> prezygotic behavioral types or seasonal types as they sometimes could tie
> into biological rhythms and such. If two popuations breed at different times
> of the year, there isn't much chance of genes flowing back and forth. Drift
> and selection can operate in this context (drift especially if the population
> is very small).
> Scott Chase
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