evolution and the standard responses...
Jul. 13th, 2006 05:48 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
acroyearFinches on Galapagos Islands evolving - Yahoo! News:
creationist wackos: but it's sitll a bird!
A medium sized species of Darwin's finch has evolved a smaller beak to take advantage of different seeds just two decades after the arrival of a larger rival for its original food source.scientists: well, it never hurts to document the obvious...
The altered beak size shows that species competing for food can undergo evolutionary change, said Peter Grant of Princeton University, lead author of the report appearing in Friday's issue of the journal Science.
creationist wackos: but it's sitll a bird!
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no subject
Date: 2006-07-13 11:58 pm (UTC)in hindsight, we now know that most of the finches there, originally given individual species classifications under the linnean standards, are actually all closely related enough to interbreed. in effect, they were all the same "species" by certain definitions from the beginning.
what is important in the finch's species definition is the isolation factor, and that holds up - these new finches have replaced their larger beak ancestors and yet remain isolated from finch populations. it is a recognizable distinctiveness and, if continued or the original finch beak disappears entirely, may qualify.
we know this is only "micro" because we observed the process. had Darwin seen the intermediates (keep reading) between the finch ancestors and the distinctive ones he documented on the Beagle, he probably would have presented the reality more strongly that "species" isn't in this instance, as he did when describing the artificial selection example of pigeon breeding.
what this ALSO goes to show is that the evolutionary idea that all creatures are intermediates, "transitions", between what came before and what will come after. these finches did not exist before, but they exist now, and we have supporting evidence that they came from their predecessors through means other than artificial selection in experimental environments. these are still treated as the same "species" as their larger-beaked ancestors because we know of them (and they still exist, though decreasingly so on that island). will it be a new species when the larger-beak ancestors are totally gone?
it depends.
150 years ago, these finches would have been considered their own species, if their ancestors weren't also there to compare to.
so what it does show (as i mentioned before the last time you brought this up) that there is no single definition of species that applies to all creatures in all environments.
it is still evolution. micro or macro doesn't matter.
no subject
Date: 2006-07-14 01:00 pm (UTC)Ah, but that's the point. Among the G.fortis (the "species" that was already on the island) were individuals that could eat small seeds and individuals that could eat large seeds. The large-seed eaters have disappeared. What is happening is that G. fortis previously filled a larger ecological niche, and now that niche has been reduced.
Evolution is a process of increasing genetic diversity amongst a population through random point-mutations in the genetic code. It allows a population to increase its ecological niche. Natural selection is the opposite: the reduction of genetic diversity within a population due to pressures against some characteristics within the population. In this case, large bills and small bills already existed in the same population, but large bills were selected against by the addition to the environment of a better-suited large-billed finch.
no subject
Date: 2006-07-14 01:36 pm (UTC)see here.
btw, your peppered moths (i've known about them since 9th grade) are covered on that site, along with answers to all of the creationist b.s. about it.
no subject
Date: 2006-07-14 02:18 pm (UTC)Certainly natural selection is a part of the whole evolutionary process, but it is the well-documented part. Extinction of a species is the extreme case of this. But it is not, in and of itself, evolution. Life must be able to expand as well as contract for evolution to occur.
I want to talk more about the allele frequency definition later, but I have to get to work!
PBS site on evolution
Berkeley intro to evolution
no subject
Date: 2006-07-14 02:32 pm (UTC)my point stands as written - this is evolution
evolution is a process that consists of a number of steps, not all of which are required, by which the population densities of specific traits (either outwardly visible or strictly genetic) change over time. an outcome of the evolutionary process is that new species can arise.
I stress again that not all potential parts of evolution (like, say, mutation) are required all the time.
the fact of evolution that is revealed by this observation is that evolution is a continual process, not one which goes in fits and starts - evolution doesn't just "start" when a new mutation arises and end when the ecology stablizes. (a common misunderstanding of the process.)
the theory of evolution explains what is happening on this island today as it reaffirms Darwin's theory of what had been happenning on those islands for the thousands of years prior to his arrive and observations.
that is all that is important about it: that the process of evolution is continuing, without our interference.
micro vs macro distinctions are unnecessary.
my comment about the creationists is that to their eyes its not evolution because its not macro evolution - to biologists eyes its evolution and macro may take place over time. in fact, we can make a prediction of it being a possibility - something creationists insist is not possible and yet is the most important part of evolution and the proof that biology is a science while (ID) Creationism remains a dead end for curiosity and science.
THAT was my point, not mincing words over "species" or even "kinds".
no subject
Date: 2006-07-14 05:44 pm (UTC)From the Berkeley site I mentioned earlier, there is this about microevolution:
Biologists who study evolution at this level define evolution as a change in gene frequency within a population.
Macroevolution is what most people mean by evolution -- the development of one species into another. (Some scientist break it down further, saying that "speciation" is the creation of a new species, and that macroevolution is at an even larger scale). Yes, I know that "species" is an unclear term. These two ideas are very different in many ways. First, microevolution is potentially reversible, macro is not. Micro can happen in one generation. Macro takes geologic periods of time. Also, according to Wiki's microevolution page, creationists don't dispute microevolution.
Multiple microevolution steps can lead to macroevolution, in fact, if macroevolution occurs, it must involve microevolution steps. But the existence of microevolution does not prove the existence of macroevolution.
According to this short article, Darwin also separated natural selection and speciation -- in fact, changes within species were already well known by then (and practiced in creating new breeds).
So my main point here is that micro- versus macro- is an important distinction, and that the former is not controversial.
no subject
Date: 2006-07-14 06:37 pm (UTC)i had no intention of using this to "prove" macroevolution, so i didn't, so stop bitching at me as if i tried to. i accept macro evolution up front and creationists can just fuck off if they don't accept that its 1) possible and 2) the best explanation for what has happened in the 4 billion years of this planets history, including us.
i said that a possibility of this is that macro might happen among these finches through these micro steps. i also said that is a predictable outcome by applying the whole theory (which includes macro) as we currently know it which makes it different from creationism which makes no predictions at all.
there are two sides to scientific theory - 1) what predictions or patterns does it make to knowns and unknowns that will support or refute it, and 2) what predictions does it make that can increase our knowledge about other things unknown but in its field.
there's supporting the theory vs. applying the theory.
the movement of the planets supported the Newtonian theory of gravity - Newton's equations had to match the already observed behavior (and fit the mathematics Kepler and Galileo had already calculated - for exaple Kepler's "K" constant ends up a ratio of Newton's G constant to the mass of the sun - Kelper's maths still hold up under Newtonian theory).
the application of the theory of gravity supported the idea that there may be a planet or other large mass beyond Uranus that is causing Uranus's orbit to fluctuate. Neptune was discovered using this application of gravity 150 years ago.
the variety of finches on the islands supported Darwin's theory. the presence of these new finches is yet more evidence supporting the current theory of evolution (specifically, the Natural Selection part along with the concepts of invasive species) with all of its genetics and populations yada yada yada.
the potential for a new species to arrive as a result of this population change is an application of modern evolutionary theory. a prediction of future events based on a solid understanding of the past with an awareness of current conditions. the science of evolution in action.
and dozens, hundreds, or thousands of years from now, however long it takes for final undeniable speciation to occur (if it ever does - ecological stability (part of natural selection) may keep things the same as they are now, and at the same time, our awareness of these changes should not be allowed to lead to interference with them thus changing natural selection into artificial selection), creationists will still be saying "well, its still a bird".
which was my f'in' point in the first place.
if macro/speciation doesn't take place in this instance, fine, macro didn't take place. the theory never said it had to, only that it is possible. is that lack of certainty a refutution of macro's relevance or support? no. it goes to show that natural selection, in and of itself, still has a huge number of variables involved that, like other chaotic events, can't have its results pinned down to any relevant certainty.
they want their fucking certainty, they can go to church and be indoctrinated in all the certainty they want. science is utterly uncertain (yet always hopeful) about everything, and scientists see no problem with that at all.
no subject
Date: 2006-07-14 07:28 pm (UTC)no subject
Date: 2006-07-14 08:05 pm (UTC)my point was its evolution and evolution is evolution at the main level, even if in the details it gets, well, detailed. as all science theories do.
to creationists, "its still a bird" is going to be their standard reply even if scientists did decide that its a new species. they widened their net by talking about "kinds" instead of species when the fruit fly speciation experiments were published ("well, its still a fruit fly").
to them, macro evolution means a dog giving birth to a cat and no amount of evidence or definitions to the contrary will break them of that strawman - which is why i didn't really feel like getting into that distinction. it was irrelevant to my point.
no subject
Date: 2006-07-14 09:40 pm (UTC)from a scienceblogger