"Raza Ali"  wrote in message
>
>    The information i am looking for is what known and accepted
> evidence is there for inter-conversion of species due to evolution?
> like one specie identified by a 'core' genetic pattern transforming
> into another specie with a totally different characteristic genetic
> pattern. Variations are there like in the influenza virus but how many
> total conversions are there?
>
You only very rarely get a saltation - a sudden jump so that the offspring
is significantly different from its parents. However it does happen, for
instance in humans two chromosomes have fused so we have one fewer pair than
chimpanzees. This must have happened suddenly - a sequence of DNA is either
one molecule or two, it can't be part way in between.

What you can sometimes see is "ring species". A famous example is the black
backed / herring gull. In Britian these are two species, but a chain of
gulls exists round the North Pole,  gradually getting more and more like the
herring gull as you go West (or is it East, I can't remeber which way). The
important point is that here we see speciation in action. If all gulls
except those in Britian were wiped out we would have two distinct species.

Two main mechanisms for speciation that have been proposed are allopatric
speciation (two populations are physically divided and subject to different
evolutionary pressures) and divergent selection (birds with big beaks eat
tough nuts, birds with little beaks eat fiddly seeds, birds with
middle-sized beaks tend to starve, so the population splits into big- and
little-beaked varieties).
>
> Also can anybody guide me on what happens at the genetic level when
> animals cross-breed?
>
Depends on the animal. Usually there are both pre-zygotic barriers to mating
(animals don't find each other sexually attractive) and post-zygotic
barriers (if a sperm and egg fuse, the offspring will probably die after a
few cell divisions). Just occasionally, as with the horse / donkey, you can
get viable hybrids.
What goes on at the genetic level depends on the animal. With plants
hybridisation often causes duplication of the entire genome. This doesn't
seem to happen with animals, for reasons unknown.
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 8/12/03 11:04:07 PM