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| 5/19 |
| 2005/8/9-11 [Science/Biology] UID:39061 Activity:kinda low |
8/9 Some news on evolution:
"Convergent Evolution in Poison Frogs"
http://csua.org/u/cyz (Yahoo! News)
\_ That evolution crap is just a "theory". In fact, God made
the world in 7 days, just like it says in Genesis. And I
challenge anyone to prove to me different. (I'll just deny
all the evidence you present.)
\_ actually, bible says he laid it to waste and remade it
in 6 days and 1 day of rest
\_ My book is holy! Yours isn't! And only I am qualified
to interpret my Holy Book!
\_ I read this article, but what it does not make clear is how it is
known that the frogs are not related. Geography doesn't tell the
story. Could they have evolved from the same frog ancestor?
\_ The article did not say the frogs are not related. In fact the
article calls the two frog species in the two continents
"cousins".
\_ Then, excuse this question from a non-bio guy, how is it
known to be a case of convergent evolution?
\_ Then there are three possibilities that it is not a case of
convergent evolution. #1: they did not evolve, ie. God
\_ Then there are two possibilities that it is not a case of
convergent evolution. #1: they did not not evolve, ie. God
is involved; #2: they did not evolve in separate
ecosystems, ie. they evolved in the same ecosystem, and
ecosystems, ie. they evolved in the same ecosystems, and
one species somehow traveled or were transported across the
Atlantic Ocean to the other continent and settled down.
#3: they did not evolve in separate ecosystems, ie. they
evolved in the same ecosystem, and the continents of Africa
and America separated only relatively recently instead of
millions (or whatever) of years ago as found by geologists.
Atlantic ocean to the other continent and settled down.
Take your pick.
\_ I am asking why they think that it *is*. I can think of
reasons why it might not be.
\_ Their reasons are that they think none of the
possible alternatives are true: #1 is not true
because species do evolve and God did not create them
in their present forms. (This is debatable.) #2
is not true because they think poison frogs and ants
can't swim across the Atlantic and nobody
transported huge population of poison frogs and ants
across the Atlantic recently. (I think this is
accepted.) #3 is not true because geologists says
so. (I think this is accepted.) So, what remains
on thir table is their original claim that "these are
two instances of convergent evolution". What remains
on our table is their claim and alternative #1.
millions (or whatever) of years ago as found by geological
scientists. Take your pick.
because species do evolve as other evidences suggest,
and God did not create them in their present forms.
(This is debated.) #2 is not true because they think
poison frogs and ants can't swim across the Atlantic
and nobody transported huge population of poison
frogs and ants across the Atlantic recently. (I
think this is accepted.) #3 is not true because
geologists says so. (This is accepted.) So, what
remains on their table is their original claim that
"these are two instances of convergent evolution".
What remains on our table is their claim and
alternative #1.
\_ Who said that the continents had to separate
recently? How do they know this adaptation is
recent? There are also lots of cases of animals
(especially frogs) being deposited in other
places by storms.
\_ There is a very easy method to determine
speciation, one only has to examine the
DNA, either mDNA or nuclear. One can
simply pick certain markers, something as
simple as a a RFLP, and determine how closely
a species is related. There is no need
to conjecture on the macroscopic since
we have had modern techniques to explore
evolution for well over fifty years now
in vitro.
\_ If they are related then I say it's not
convergent evolution.
\_ Convergent evolution, as stated in the
article, is "the process in which
organisms not closely related ......".
So the two poison frog species can be
related, and so are the two ant species.
They just need to not be closely related.
\_ Who defines how close? I mean,
they are both frogs so of course
they are related in some way.
\_ Hmm, good point that the adaptation might not
be recent. Let's see what proof they have in
the full report in the upcoming issue of
Proceedings.
\_ it's stupid, one frog in 22 eats a cigarette some lame
scientist dropped and now they are evolving some new type
of nicotine defense mechanism?
\_ i agree. doesn't explain that ants eat plants..
ants eat insects, honeydew and fruits.. and leafcutter
ants cut leaves for storage (heating up their home)
but not food.. this article blows..
\_ Where in the article does it say anything about nicotine defense
mechanism? The mechanism in the article is about alkaloids.
\_ nicotine is an alkaloid
\_ Yes, but not all alkaloids are nicotine.
\_ can you read "However, this is some of the most
convincing evidence that plant-insect-frog toxin food
chains do exist"
\_ Yes I saw that, but please read the whole article. Ths
observation on nicotine, and its suggestion of
plant-insect-frog toxin food chains, are separate from
the obesrvation on alkaloid defense mechanism.
\_ but half the article is on this. and the
most direct quotes from the scientist are about
this and not the alkaloid defense mechanism..
\_ yeah, but it shows how stupid these scientists
are... "most convincing" evidence but no facts
or evidence to be found .. so they claim
it as fact.. a lot of this bs is pervasive
among evolutionary scientist who forget to use
the scientific method and keep making theories
into facts..
\_ Why did you say they found "most convincing"
evidence and then say they found no evidence? If
you meant no conclusive evidence, that's true and
the article never claims that there is conclusive
evidence. Also, you said the article claim the
toxin food chain as a fact. The article never
claims that either. It stated that "they are not
sure how the chemical enters the frog's system.",
and that they only have convincing evidence, not
conclusive evidence.
\_ i agree, isn't it better that animals would
prefer to eat the nicotine laden frogs because
they'll get addicted to nicotine? and get
a good buzz out of it.. .. ? hehe
\_ that's a lot of faith.. a plant that has no
nicotine to be found anywhere, yet they
use this as the "most convincing" evidence?
sounds like bad science and blind faith.
\_ This is not bad science, because they are only using it
as convincing evidence, not conclusive evidence, and
they are not drawing any conclusion out of it. Also,
they are not concluding whether there is or is not any
nicotine-producing plants, because "Our team has not
yet conducted a survey of possible nicotine containing
in the area where the nicotine-frog was found". |
| 5/19 |
|
| csua.org/u/cyz -> news.yahoo.com/s/space/20050809/sc_space/convergentevolutioninpoisonfrogs com Tue Aug 9, 9:00 AM ET Scientists have discovered one of the most intricate examples of converge nt evolution with the help of South American "poison" frogs and ants and their cousins in Madagascar. Poison frogs can't make their own poison--they steal it from ants. Poison frogs secrete a variety of chemicals called alkaloids to create a poiso nous defense against predators. Since they can't produce alkaloids on th eir own, these frogs maintain a steady diet of specific alkaloid-rich an ts to keep up their defense. Now, Valerie Clark of Cornell University and her colleagues have detailed two instances of convergent evolution--the process in which organisms n ot closely related independently acquire similar characteristics while e volving in separate ecosystems--between frogs and ants on two continents . First, species of ants high in alkaloids had to evolve on two separate co ntinents. "The ants had to be there with alkaloids for the frogs to evolve to get a lkaloids in their skin," Clark told LiveScience. Then the frogs had to develop a resistance to the alkaloids--instead of s pitting out the ants or passing the alkaloids through their systems, the frogs became able to keep their ant dinners down. Then they evolved to make use of the alkaloids themselves. Also, both the frogs in South America and Madagascar evolved to have "don 't-eat-me" skin colorings, the final step in a remarkable tale of multi- step convergent evolution. Up until now, scientists have mainly studied frogs from South America and Australia. But Clark and her colleagues showed that the Madagascan frog s needed the same types of food to be poisonous. They examined the stomach contents of 21 frogs from the genus Mantella an d found that alkaloid rich ants made up 67 percent of their food intake. ci garettes--in one Mantella baroni frog out of 22 examined. Nicotine is pr oduced by plants and can sometimes be found in animals that eat these pl ants. But so far no nicotine-producing plants have been found growing in the area where this frog was found. This was the first time researchers observed this phenomena and they are not sure how the chemical enters t he frog's system. "Our team has not yet conducted a survey of possible nicotine containing in the area where the nicotine-frog was found, and none of our team's in sect samples yielded nicotine in chemical analyses," Clark said. "Howeve r, this is some of the most convincing evidence that plant-insect-frog t oxin food chains do exist." Other characteristics the Madagascan frogs share with their South America n cousins include terrestrial eggs, small body size, and toothless jaws. Scientists have long known that frogs rely on a diet of ants, beetles, an d millipedes to produce their poison. When poison frogs are captured and kept in captivity, they retain skin alkaloids for years. But they can't make more without eating the right types of ants. Frogs ke pt in captivity and fed a steady diet of flies, for example, don't secre te alkaloids. com for more daily news, views and scientific inqui ry with an original, provocative point of view. LiveScience reports amaz ing, real world breakthroughs, made simple and stimulating for people on the go. |