Modern horses are believed to have given rise to Prezwalski's horse. Modern
horses have 64 chromosomes Prezwalski's has 65. One can not get more
intermediate than that and yet it is still saltational. There is no animal
with 64.5 chromosomes. These two can produce fertile offspring, but the ass
is believed to have arisen in the same way except in reverse, a chromosomal
fusion. The donkey has 62 chromosomes and they can not produce fertile
offspring. What is transitional about all this?
I see no reason why what I can see going on today should have some type of
limit. What is to prevent future fusions or fissions from occurring? The
Persian onager has 54 or 55 chromosomes, the Kiang has 55 or 56. Burchell's
zebra has 46 chromosomes and the plains zebra has 44.
Even most creationists would say that the 'horse-kind' came from one animal
after the flood 5000 years ago. This certainly is rapid evolution.
The genus _Rattus_ has 137 species and is known to have originated just
before the middle ages. (see L.Drew Davis A list of Observed speciation
events" Talk.Origins archives. and G. H.H. Tate, "Some Muridae of the
Indo-Australian Region," Bull, Amer. Museum Nat. Hist. 72: 501-728, 1963)
On Mauritius, a new type of rat was developed within the past 400 years (rats
were not on the island prior to the voyages of discovery). The Mauritius
rats have 42 chromosomes compared to 38 for the rest of Oceania, The typical
Oceania rat has 4 large metacentric chromosomes, 2 small acrocentric and 14
small metacentric with 18 classified others. The Mauritius rat has 4 large
metacentrics (like the Oceania) 10 small acrocentrics, 10 small metacentrics
(like the oceania) and 18 others. Asian rats have no large metacentrics and
Ceyloneses rats have only 2. Once again, where are the transitions? Since
we know that the rat was not on the island 400 years ago, and this rat is
unique, a speciation event occurred there during the past 400 years. (See
also T. H. Yosida, et al, "Mauritius type Black Rats ..." Chromosoma,
75:51-62 1979). What is to stop the further differentiation between these
rats?
glenn
glenn