Evolution Question???
- Thread starter ewurm
- Start date
It is commonly thought that fish first evolved in saltwater around 510 million years ago, but some suggest that the first fish may have been anadromous.
Another good link!! http://www.pnas.org/cgi/content/full/96/9/5107
Excerpt from page
Lake Malawi contains a flock of >500 species of cichlid fish that have evolved from a common ancestor within the last million years. The rapid diversification of this group has been attributed to morphological adaptation and to sexual selection, but the relative timing and importance of these mechanisms is not known. A phylogeny of the group would help identify the role each mechanism has played in the evolution of the flock. Previous attempts to reconstruct the relationships among these taxa using molecular methods have been frustrated by the persistence of ancestral polymorphisms within species. Here we describe results from a DNA fingerprinting technique that overcomes this problem by examining thousands of polymorphisms distributed across the genome. The resulting dendrogram averages the evolutionary history of thousands of genes and should accurately reflect the evolutionary history of these species. Our tree resolves relationships among closely related Lake Malawi cichlids and provides insights into the pattern of speciation in this group. We demonstrate that adaptive divergence in trophic morphology played an important role during the early history of the lake. Subsequent species diversity has arisen with little change in trophic morphology, which suggests that other forces are responsible for the continued speciation of these fishes.
Excerpt from page
Lake Malawi contains a flock of >500 species of cichlid fish that have evolved from a common ancestor within the last million years. The rapid diversification of this group has been attributed to morphological adaptation and to sexual selection, but the relative timing and importance of these mechanisms is not known. A phylogeny of the group would help identify the role each mechanism has played in the evolution of the flock. Previous attempts to reconstruct the relationships among these taxa using molecular methods have been frustrated by the persistence of ancestral polymorphisms within species. Here we describe results from a DNA fingerprinting technique that overcomes this problem by examining thousands of polymorphisms distributed across the genome. The resulting dendrogram averages the evolutionary history of thousands of genes and should accurately reflect the evolutionary history of these species. Our tree resolves relationships among closely related Lake Malawi cichlids and provides insights into the pattern of speciation in this group. We demonstrate that adaptive divergence in trophic morphology played an important role during the early history of the lake. Subsequent species diversity has arisen with little change in trophic morphology, which suggests that other forces are responsible for the continued speciation of these fishes.
koliveira said:
I watched that today and it was so cool. They even mentioned that fish in the amazon originated from the salt waters. That's why rays and such exist in the amazon.
i agree with rottbo with the we all came from a single celled organism. I like to think of evolution as a mutation that happens when you are developing, like something happens to your genes, and sometimes this mutation will benefit you. Mutations happen all the time, but usually it turns out for the worse.
Why don't we see evolution happening before us? Well it taks a long time to see it actually take affect. For example there might be a single fish that was born with a defected gene that allowed them to change their apperance to camoflauge themselves. We might not know about it because this 'mutant' fish might live deep in the amazon somewhere. Now this little fish has an advantage over his brother and sisters in that if a predator is about to attack is, it can change its appearance and the predator will get confused, this little mutant fish survives another day, where as his brothers and sisters can't do this and so get eaten by the predator. Eventually this mutant grows up finds a mate and his defective gene maybe passed to one or a couple of his offspring. This keeps happening until we notice it. It could takes AGES.....
Why don't we see evolution happening before us? Well it taks a long time to see it actually take affect. For example there might be a single fish that was born with a defected gene that allowed them to change their apperance to camoflauge themselves. We might not know about it because this 'mutant' fish might live deep in the amazon somewhere. Now this little fish has an advantage over his brother and sisters in that if a predator is about to attack is, it can change its appearance and the predator will get confused, this little mutant fish survives another day, where as his brothers and sisters can't do this and so get eaten by the predator. Eventually this mutant grows up finds a mate and his defective gene maybe passed to one or a couple of his offspring. This keeps happening until we notice it. It could takes AGES.....
sqratch said:
you are kinda contradictiong yourself...
Evolution Theory:
Fish A...sprouts legs therefore able to walk
Fish B...sprouts wings therefore able to fly
It would be like you just growing gills right now.
Adaptation/Mutation Theory:
Moth A: Brown with dark spots....doesnt get eaten by owls because it is camoflauged against a birch tree.
Moth B: Dark Brown almost Black....gets eaten by the owl because it doesnt blend in.
(both moths are same species....black one is a mutation)
During Industrial Revolution the Birch trees get covered in Soot.
Moth A: gets eaten by owls because it can be seen on the dark background
Moth B: doesnt get eaten because owl cant see it.
Therefore Moth A type population is very much less and the Moth B thrives in the Industrial area. Moth A thrives in the other areas...leaving both colored moths.
Adaptation/Mutation is not seen in human because we have no natural predators. if we did those of us that could run faster (just an example) would thrive because we would escape, leaving the slow ones behind. over time the human race would be made up of very fast people.
Evolution is a process that takes very little time...just one day a fish next day a walking/flying animal.
Adaptation/Mutation takes many years...therefore we dont see it just happening.
make your own decision...but remember Darwin the Godfather of Evolution denied his theory of evolution. He took the side of Adaptation/Mutation which is also know as "Surival of the Fittest" or "Natural Selection". He understood that a Finch would not just change its beak to better eat a nut or better eat a berry. but a mutation would allow one or the other to thrive depending on the food source in the area. that is why there are very similiar animals in different regions. years ago they may have been the same animal but a mutation allowed one to thrive in one region and the other in another.
But hey just my .02
