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Evolution

Posted Mar 7, '13 at 4:54pm

HahiHa

HahiHa

5,453 posts

Knight

Interesting. So it helps animals find fruits more easily? Though they still lacked any evidence when the press release was written in 2004.

But why does it have to be a neurotoxin? As written in the article, they found birds that died of alcohol poisoning. Finding fruits more easily to die of alcohol poisoning makes no sense from the point of view of the bird. The fruit however gets eaten and the seeds dispersed, and the alcohol makes sure the brids are attracted. To me i sounds like it's a neat strategy of the plant, misusing the way a neurotoxin affects us with a certain addicting potential.

I ask myself why children don't like alcohol. If it was such a great advantage, why isn't the attraction working from the first moment on? I'm still not sure it is really an inbuilt evolutional trend of ours, I'd wager it's more of a hijack of our neural system by the fruit.

 

Posted Mar 9, '13 at 5:48am

MageGrayWolf

MageGrayWolf

9,800 posts

Knight

Don't know if this will drum up any conversation or not but it still seemed interesting.

Genetic study of house dust mites demonstrates reversible evolution

In evolutionary biology, there is a deeply rooted supposition that you can't go home again: Once an organism has evolved specialized traits, it can't return to the lifestyle of its ancestors. There's even a name for this pervasive idea. Dollo's law states that evolution is unidirectional and irreversible. But this "law" is not universally accepted and is the topic of heated debate among biologists. Now a research team led by two University of Michigan biologists has used a large-scale genetic study of the lowly house dust mite to uncover an example of reversible evolution that appears to violate Dollo's law.

..."Parasites can quickly evolve highly sophisticated mechanisms for host exploitation and can lose their ability to function away from the host body," Klimov said. "They often experience degradation or loss of many genes because their functions are no longer required in a rich environment where hosts provide both living space and nutrients. Many researchers in the field perceive such specialization as evolutionarily irreversible."
 

Posted Mar 9, '13 at 9:52am

HahiHa

HahiHa

5,453 posts

Knight

It would be kind of stupid to think a parasite would have to keep it's specialized apparatus even if it's not used anymore. In this aspect, degradation to a state similar to an ancestral one is certainly possible, but to be understood as another adaptation to another environmental change.

It certainly also depends on the genetic background of the structure at hand. If it is interlinked with several other functions and such, it is unlikely to just vanish. If desactivating the expression of such a structure is relatively easy, why not?

 

Posted Mar 9, '13 at 10:48am

Kasic

Kasic

5,746 posts

In evolutionary biology, there is a deeply rooted supposition that you can't go home again: Once an organism has evolved specialized traits, it can't return to the lifestyle of its ancestors.


I always took this to mean something along the lines of this: Things don't "unevolve" even if they lose features/traits. It's like a chain, 1+2+3+4, where any change is counted. Even if something evolves some specialized feature and loses it, the organism did not "revert," it responded once more to environmental forces.

Logically, the same environmental forces produce the same changes. Slightly different perhaps, due to the random nature of selection and adaptation, but the same nonetheless. Isn't that why the structure of wings are similar between completely different species? Isn't that why we find strikingly similar behaviors and traits?

I would pose that the dust mites are not reverting or demonstrating reversible evolution. They are simply responding to their environment. Whatever specialized adaptions for living off a host do not matter off the host, and thus eventually die out. Likewise, the ones that are not specially adapted to a host do not flourish as much as the specialized ones and eventually die off.

Evolution is the change of a species over time. Whether such change is changing back to what it was before is irrelevant.

To put it into math terms, evolution is an absolute value. Whether its |1| + |-1|, |1| + |1|, |-1| + |-1|, the answer is always two. A change occurred, whether it added or subtracted a feature. The change is what we're counting.
 

Posted Mar 13, '13 at 5:57am

HahiHa

HahiHa

5,453 posts

Knight

Mage posted this in another thread:

He was a monkey, just like you and me.
But snakes are a subset of the order, Squamata; That means lizard. If snakes evolved from lizards, do they stop being lizards at the moment they become snakes? And when exactly is that moment? It turns out this is another confusing convention in Linnaean taxonomy which is corrected by cladistics. Paraphyletic groups shouldnt exist in phylogenetics, nor would systematic classification permit the emergence of new species to add another equivalent category. Instead existing branches split into successive subsets that are each monophyletic, sharing a common line of descent from which they can diverge but never detach. This means snakes will always be a subset of lizards and apes would still be monkeys.

It is true that Linnaean taxonomy, with classes, orders and all that isn't really used anymore; instead you just speak of a taxon, or taxa (genus and species are still in use due to the scientific names). Thus, "birds" is a taxon within the taxon of "dinosauria".

I don't agree with the conclusions of your post however. Lizards and snakes, together with amphisbaena, are different taxa within the squamata (Squamata does not mean "lizard", but "scaled reptiles"). Of course snakes evolved from a lizard-like ancestor, but so did modern lizards.

Our phylogeny is another problem altogether. We are not monkeys, for "monkey" is a paraphyletic group that includes a big part of the primates, but not apes. As you said, paraphyletic groups should not be used in phylogenetic arguments (they're evil :P), so yes, we're primates and we're apes ("apes" being a monophyletic taxon).
 

Posted Mar 13, '13 at 12:53pm

Kasic

Kasic

5,746 posts

I don't agree with the conclusions of your post however.


Neither do I. They seem to follow the logic of kittens born in the oven being muffins. Simply because something branched off from the same spot at a point in time does not make them forever stuck with the name.
 

Posted Mar 13, '13 at 2:27pm

HahiHa

HahiHa

5,453 posts

Knight

Well it depends. It IS important to keep in mind the evolutionary background of the different species. The problem I have with Mages post is that it uses the term "lizard" for modern lizards as well as for the common ancestor of lizards, snakes and amphisbaena. This is essentially using one and the same term twice, in different contexts; for let's not forget that most names of extant animals were given without knowledge of phylogeny (which is for example why the term "reptile" has no significance anymore unless you count in birds). That's why the group containing lizards and snakes is best referred to as squamates, or lizard-likes, rather than lizards.

 

Posted Mar 13, '13 at 8:08pm

MageGrayWolf

MageGrayWolf

9,800 posts

Knight

Here's the video and transcript that goes along with it. It get's more into explaining why.

Human Evolution: Did We Come From Monkeys?
Turns out we DID come from monkeys!

Basically what it's saying is all the qualities that classify something as a monkey apply to use and other apes. It's not saying something is forever stuck in the classification. It's also saying that the only reason we don't classify humans as monkeys is based on subjective criteria.

"So the only way to properly classify anything is according to the collective characters common to everything already accepted in that category without making exceptions for certain ones."

So what sets us apart?

 

Posted Mar 14, '13 at 5:28am

HahiHa

HahiHa

5,453 posts

Knight

So what sets us apart?

Primarily a number of skeletal and genetical characteristics. If you're arguing that this is subjective, then all phylogenies are.

We didn't evolve from monkeys because "monkeys" (an old colloquial paraphyletic term for the modern animals only) are two branches of the simian tree, old world monkeys and new world monkeys. OWM, NWM and apes evolved more or less separately form a common anthropoid ancestor. It's well possible that there's a bit of a blurry concerning when which group split off, but it's safe to say that both monkeys and apes evolved from a simian (monkey-like, if you want) ancestor.
 

Posted Mar 14, '13 at 10:24pm

MageGrayWolf

MageGrayWolf

9,800 posts

Knight

Not willing to concede just yet but I will have to put my argument on hold for the time being due to being very sick and can't focus the way I need to for this. I would appreciate it if someone played devils advocate in my place for the time being so this doesn't die.

We didn't evolve from monkeys because "monkeys" (an old colloquial paraphyletic term for the modern animals only) are two branches of the simian tree, old world monkeys and new world monkeys. OWM, NWM and apes evolved more or less separately form a common anthropoid ancestor.


The argument is that this isn't accurate and we can apply it to the earlier form.
 
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