Hmm, maybe hummingbirds and bees, but not birds in general. Also, I have a pic for you.
Take that you spheroid-earth believer!
Posted on 05/03/2002 10:20:22 AM PDT by Gladwin
Scientists say they have found the fossilised remains of the earliest known flower. It was discovered in a slab of stone in north-east China and the plant is thought to have lived at least 125 million years ago.
Researchers at the University of Florida say the species could be the predecessor of all flowering plants. They say it probably grew in shallow lakes shared by dinosaurs and other prehistoric creatures.
The plant, called archaefructus sinensis or "ancient fruit from China," is of a species never before seen, said David Dilcher of the Florida Museum of Natural History and the University of Florida.
"It is like the mother of all flowering plants," he said.
Professor Dilcher is the co-author of a study published on Friday in the journal Science. He worked with Ge Sun, a geologist at Jilin University in Changchun, China, and other researchers.
Botanists had long considered a woody plant from New Caledonia as the most ancient of flowering plants. But Professor Dilcher said the new discovery was even older. "It changes our whole impression of what is the oldest of all flowering plants," he said.
The flower's closest "modern relative" is probably the water lily, said Professor Dilcher, because it apparently lived in clear, shallow waters, with its flowers and seeds extending above the surface.
The discovery suggests that flowering plants started out as herbs that were able to reproduce quickly, he said. It "was not a flashy flower," he said. The plant's flowering part had no real petals, but acted only as a reproductive unit - essential for its survival.
"The reason we can say it is a flowering plant is that the seed is enclosed inside of carpels [female part] of the fruit," said Professor Dilcher.
Other experts in Science said more research was needed before the new flower was generally accepted as the most ancient of flowering plants.
But Peter Raven of the Missouri Botanical Garden in St Louis said it "may be the most significant flowering plant ever found."
"raising the birthrate also raises the mutation rate"
Correct. Mutation rates per se are less important than beneficial/deleterious ratio. Per theory, this ratio is increased with sex because for two reasons. One is that mutations are spread across different genetic backgrounds allowing for adaptive allele substitutions and the other is that clonal competition (competition with other beneficial mutations)present in asexual populations is decreased. Further, for males in dimorphic species, additional screens take place before recombination; deleterious mutations never make it past the male gamete stage.
All this is said with a caveat. Many of the models attempting to test various of these theories yield poor results. For example, from Multidimensional epistasis and the disadvantage of sex (nota bene edited by John Maynard Smith before publication!): "To summarize, it seems that unless selection can be approximated by the fitness potential model, sexual reproduction usually impedes, rather than facilitates, fixations of new, beneficial alleles."
Recent reviews in Nature Reviews Genetics are more hopeful. When models are tested with parameters which approximate real life situations (ie finite populations instead of the usual infinite), results are more positive.
Everybody agrees this is not a straightforward problem.
I noticed multiple definitions of the mutation rate when I looked it up.
mutation rate
The number of mutations arising in an individual per nucleotide site or per gene per unit time.
Up to this discussion I had considered mutation rate as being an individual's parameter. It is clear that if the mutation rate is tied to a locus independent of the number of individuals, and since the number of genes is fixed for an organism, that more organisms will produce more mutations in a unit time raising the mutation rate per gene, consequently the birth rate is tied directly to that definition of the mutation rate. I assume then the mutation rate per gene is the definition used.
I was assuming mutation event per cell division. In general this is greater for prokaryotes than eukaryotes. The division of asexual and sexual reproduction doesn't fall exactly among those categories, but largely so.
Hmm, maybe hummingbirds and bees, but not birds in general. Also, I have a pic for you.
Take that you spheroid-earth believer!
Great pic. Entirely consistent with the latest findings: TIME CUBE .
I hereby resolve that I shall never make a direct post to another creo boy. All my posts will be to evos, or to "All" or to myself (placemarkers). I've learned that dialoge with a creo (with a very few exceptions) is an absolute waste of time, and tends to degenerate into personal insults.
How can ideas be discussed without direct exchanges? Not a problem. If a creo boy says something that needs a response, I can always address my comments to an evo and say: "See post #...? Clearly the poster has no idea that ...." And if the creo responds directly to me (and calls me a liar, a fraud, etc.), the way I hope to deal with it is to ignore it. Anyway, that's my personal resolve. I see no other way around the impassable barrier of what amounts to inter-species communication.
I saved a bunch of stuff from my reply queue to HD. Not just errors were exposed there, but hypocrisy. I'll never be able to link what I have to a thread, but I'll know.
I hereby resolve that I shall never make a direct post to another creo boy.
Too general for me, but I'm still through with Blue Slimer and wondering why I bother in some other cases.
Somebody mentioned a camel hump as an example of a macroevolutionary event. You countered with a sixth finger mutation and a camel family hybrid. I pointed out that those two are conceptionally very different and asked you what definition of macro you were using. You evasively responded that you didn't make up the definition of macro. Then you said that a hump or sixth finger does not a species make.
In fact, a camel hump is one of the defining characteristic of a camel species. Artificial hybrids notwithstanding.
Of course, a camel hump describes a camel. It is after all, a camel hump. I said a hump does not make a camel. There is a logical difference. If it has a hump then it is a camel is not equivalent to If it is a camel then it has a hump(at least one).
Neat link. It's a beautiful fossil.
So? The original claim was a that the camel hump is a macroevolutionary event, not a camel.
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