Both your statements are false.
Normally it takes more than 100,000 years for a large creature like a mammal to evolve into a new species, (i.e. cannot mate with fertile offspring with any closely related specie) but extreme selection pressure lasting 8000 years has done it once, at least. Following from my post in an earlier version (III) of this thread:
The Santa Catarina's Guinea Pig, Cavia intermedia, also known as the Moleques do Sul Guinea Pig is a guinea pig species from South America. It is found in Brazil on only the small island of Moleques do Sul in the state of Santa Catarina. The island has a surface area of only 10.5 ha, the Guinea Pig's geographical distribution of only 4 ha is one of the world's smallest for a mammal. From: http://en.wikipedia.org/wiki/Santa_Catarina's_Guinea_Pig
{Note the tiny island is about 90% bare rocks – very little food –extreme environment pressure for 8000 years.}
“… We can know with certainity that the evolution of a new species of mammals (called preá) in only 8000 years has occurred at least once. …
For it to happen the gene pool was very tiny (not more than 40 animals); there were no predators who might eat the better adapted animal before it could reproduce; the entire population was under great stress for all of the 8000 years, literally on the edge of extinction, so any slight advantage was very significant aid to not being among those that starved to death. Obviously scientists were not observing 8000 years ago, but we are certain the sea level was lower then and that the tiny island these mammals live on now was part of a much larger island back then. Thus, back then they were an interbreeding part of a large population, which still exist, with little survival stress. Thus, when the sea level rose, we know they were isolated - an essential requirement for evolutionary divergence to produce a new species. …” Above from: http://www.sciforums.com/showpost.php?p=2208297&postcount=172
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Below from: http://www.sciforums.com/showpost.php?p=2205207&postcount=83
“…There are approximately 40 little animals, called Preá in Portuguese, living on tiny island called Moleques do Sul, which is about 8 km separated for a much larger Island called Florianopolis that have been studied by Pontifica Universidade Católic under leadership of Sandro Bonatto.
About 8000 years ago, these two islands were one as the sea level was much lower. The tiny island is about the size of a football field and mainly rocks. But has some grass on ~10% of it.
These Preá are so inbreed that DNA tests (type used in Brazil to determine disputed paternity, at least) cannot determine any differences. They are about half the size of the main island animals they evolved from during 8000 years of separation. Smaller size was favored by selection because of the very limited food supply. They are the only mammals on the tiny island and have no predators. - I.e. population is limited only by the lack of food for more than 40 but probably has been slightly increasing as they evolved to be ever smaller each 1000 years. (Probably no more than 20 of them lived after the connection to the main island was cut off 8000 years ago by the melting ice.)
They are now a new species (Cavia Intermedia) but closely related to Cavia Magna of the main island. They are about the size and shape of a small rat, but with a face that looks much like a monkey, or even human, and fur covered (except the feet) with no tail. Head and back fur is brown and belly fur is whitish grey.
Until they were discovered it was not thought by experts that a population of only 40 animals max could survive for thousands of years. They have, no doubt, lived all that time on the edge of extinction and practiced incestual mating with no ill effects, at least for the last 6000 or 7000 years. They are all now genetic identical. The ill effected off springs of inbreeding were selected out long ago as all live hungry on the edge of extinction at least in the mild winters. (Perhaps, like bears, they store fat during the summers - just my guess, not mentioned in the paper.)
Their tiny island is part of a state park, now with special protection - only qualified researchers can legally visit, but some fishing boats do at times. The great fear is that one will leave a cat on the island. - Then this recently evolved new species will go extinct.
Here is a photo of one being held, belly up, easily in the palm of a hand. {Original from page A14 of the Folio de Paulo of 18 March 2009.} ... These preá are sooo cute, with their little quasi-human quasi-monkey faces* peering out from great spread of surrounding facial hair. I bet they would make great pets. For protection of the species I hope some of the researchers think so also and steal a few for breading on the mainland and eventual sale as pets, before some fisherman's cat eats them all in less than a month.
I also note that forward looking eyes the preá have, instead of the side looking eyes of a guinea pig are very much to be expected in this evolution as they facilitate depth perception and with no predators to eat them, there is no advantage to side mounted eyes as most prey animals have - only the "cost" of poor depth perception so side mounted eyes were selected against during the 8000 years. The preá surely scampered between rocks and jumped* over some too trying to find a blade of grass to eat before another preá did. - Good depth perception would be strongly selected for.
* Note also their hind legs have evolved to be good for jumping, like a rabbit, and very different from those of the main land guinea pigs they evolved from in only 8000 years.
From version II of this thread, here is more on them: http://www.sciforums.com/threads/denial-of-evolution-ii.91631/page-9#post-2208297 As ignorant new posters keep appearing, I'll probably need to dig up these post again for version V of this thread when it is created.
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