Evolution 101- part 16: The Mystery of Iguana Island

Remember, normal text is copied from Evolution 101 by the Understanding Evolution team! (with special guest star Charlie Sheen!) http://evolution.berkeley.edu/

BOLD font is me, Rent A Friend 2000, being Bold.

Defining microevolution: Microevolution is evolution on a small scale — within a single population. That means narrowing our focus to one branch of the tree of life.

I think you’ll find it means further applying the term “Evolution” in a place it doesn’t belong. Here’s a metaphor: Getting rich is merely the result of differentiating your financial income. Remember when your boss cut your Christmas bonus in half? That was an observable difference in your financial income. It’s proof that you are getting rich!

And now, on with the show:

We’ve defined microevolution as a change in gene frequency [editor’s note: A STATISTICAL change] in a population and a population as a group of organisms that share a common gene pool — like all the individuals of one beetle species living on a particular mountaintop.

Imagine that you go to the mountaintop this year, sample these beetles, and determine that 80% of the genes in the population are for green coloration and 20% of them are for brown coloration. You go back the next year, repeat the procedure, and find a new ratio: 60% green genes to 40% brown genes.

 beetle genes

You have detected a microevolutionary pattern: a change in gene frequency. A change in gene frequency over time means that the population has evolved.

Lift intellectual club, aim at deceased equine mammal, and strike. Repeat process.

This process will never turn bacteria into wolves or cabbage. It doesn’t even attempt to explain where the green or brown came from, let alone the beetles the green and brown is found on. The population here has NOT changed- certainly not in any way significant enough to warrant saying it has “evolved.” There has been no genetic change- only a statistical change. These people are simply confusing adjectives for nouns.

The big question is, how did it happen?

I think the first question is, what happened? You started with green and brown beetles and, over many years wound up with green and brown beetles. You can ask HOW after you find a WHAT.

Let me hit you with an auto metaphor:

We are admiring the new hybrid vehicles which use more electrical power than gas. You wonder aloud where the hybrid car came from.

“Well,” I reply, “Last year more buyers preferred the red model, but this year more blue cars have sold.”

“No,” you say, “I meant, where the did the cars come from? How did they come to exist in the first place? Where did the hybrid technology come from? A team? A particular scientist or inventor?”

I laugh politely and reply, “I’ve just told you. Last year more people bought red hybrids, and this year they bought more blue ones. So, the number of blue hybrids on the road is now more than the number of red hybrids.”

“Maybe you didn’t hear the question,” you say. “I’m asking WHO invented the hybrid car in the first place. I don’t care how many red ones to blue ones. I want to know how the car in any color came to be.”

I shake my head in pity. “I’ve just told you. By observing the changes in the percentages of red hybrids to blue ones, we are seeing the mechanism by which these cars came to be.”

What you say next is too rude to print. Needless to say, you should wash your mouth out with soap. 

Defining a species: A species is often defined as a group of individuals that actually or potentially interbreed in nature. In this sense, a species is the biggest gene pool possible under natural conditions.

If two lineages of oak look quite different, but occasionally form hybrids with each other, should we count them as different species? There are lots of other places where the boundary of a species is blurred. It’s not so surprising that these blurry places exist — after all, the idea of a species is something that we humans invented for our own convenience!

This is the truth. There is literally no good, universally accepted definition of “species.” Did you know that EVERY breed of dog is one species? From boxer to schnauzer to beagle to mastiff, ALL of them are Canis lupus familiaris. That’s 400 varieties as different as wiener dog and poodle, but all one species. Keep that in mind as the Understanding Evolution Team tries to dazzle you with…
fruit flies.  

Defining speciation: Speciation is a lineage-splitting event that produces two or more separate species.

We already admitted that we don’t really have a good definition for “species.” Now we’ll tell you where new ones come from. Can you say ‘slight of hand’?

Imagine that you are looking at a tip of the tree of life that constitutes a species of fruit fly. Move down the phylogeny to where your fruit fly twig is connected to the rest of the tree. That branching point, and every other branching point on the tree, is a speciation event. At that point genetic changes resulted in two separate fruit fly lineages, where previously there had just been one lineage. But why and how did it happen?

Just a reminder from many chapters back: phylogenic tree of life: A fictional piece of guesswork based on the assumption of the evolutionary story where data is plugged into the places where they best fit the pre-existing story. Now we’ve added that we can’t really say what a species is, but each branch is where one species becomes two species . Got all that? OK, moving on.

fly speciation

The branching points on this partial Drosophila phylogeny represent long past speciation events. Here is one scenario that exemplifies how speciation can happen:

  • The scene: a population of wild fruit flies minding its own business on several bunches of rotting bananas, cheerfully laying their eggs in the mushy fruit…

I cut this story out for brevity. It’s a beautiful story of love lost, love gained, and bananas. In a nutshell- some flies get separated from some others, and over time each changes. When eventually they met again, Shazam! They are now TWO DIFFERENT SPECIES (whatever that is) of FRUIT FLIES! Which look almost identical. They’re fruit flies for heaven’s sake. Even THEY can’t tell each other apart.

What this fails to show is an increase in genetic information. Dogs show a much better and easier to see version of diversification coming from an original parent kind, but they, again, show a gradual decrease in genetic information with each subsequent generation. If you’d rather look at fruit flies than domestic dogs, may I suggest that you are not well and will probably die alone.

This is a simplified model of speciation by geographic isolation, but it gives an idea of some of the processes that might [Editor’s note: “Might”] be at work in speciation. In most real-life cases, we can only put together part of the story from the available evidence. However, the evidence that this sort of process does happen is strong.

The evidence is so strong that, instead of a real life and known example, they chose to create a cartoon about fruit flies based on speculation of what “might” happen. Do they not have access to Wikipedia? Could they not look one up? Or are the examples of this “Strong” evidence also hypothetical? Am I the only person who finds this suspicious? This evolution 101 is like an add for prescription drugs with three pages of tiny fine print.

Perhaps the reason why they offer no actual examples of evolution can be found in the results of actual experimentation with fruit flies: “The fruit fly has long been the favorite object of mutation experiments because of its fast gestation period (twelve days). X-rays have been used to increase the mutation rate in the fruit fly by 15,000 percent. All in all, scientists have been able to catalyze the fruit fly evolutionary process such that what has been seen to occur in Drosophila is the equivalent of many millions of years of normal mutations and evolution.”—*Jeremy Rifkin, Algeny (1983), p. 134.

Sounds good, right? MILLIONS of years of normal mutations and evolution! Imagine what these experiments have produced!

“Fruit flies refuse to become anything but fruit flies under any circumstances yet devised.”—*Francis Hitching, The Neck of the Giraffe: Where Darwin Went Wrong (1982), p. 61. Hmmm… Seems that far from creating life in the lab, we can’t even get it to CHANGE in the lab. Rotten little, uncooperative insects. Don’t they know we’re trying to prove evolution here? Did anyone tell them? Whose side are they on anyway?

Causes of speciation: Geographic isolation
In the fruit fly example, some fruit fly larvae were washed up on an island, and speciation started because populations were prevented from interbreeding by geographic isolation. Scientists think that geographic isolation is a common way for the process of speciation to begin: rivers change course, mountains rise, continents drift, organisms migrate, and what was once a continuous population is divided into two or more smaller populations.

geographic isolation

It doesn’t even need to be a physical barrier like a river that separates two or more groups of organisms — it might just be unfavorable habitat between the two populations that keeps them from mating with one another.

I’ll admit, this is probably true. What we did with dogs domestically or with corn and cabbages almost certainly happens in the wild, which is why we keep finding new species of beetles every year, even though we already know of 30,000 (though, the vague definition of “species” is probably another reason). But again, even in their example, the species diversifying are NOT gaining information. They are expressing unique parts of the information which already existed in the parent population. Evolution has to explain where the parent population got the information, not just watch how it gets disseminated in later generations. We are not finding beetles that can sing, or who have ears. The differences only go so far, and in MANY cases probably don’t warrant the title of being different species.

See their definition above. “A species is often defined as a group of individuals that actually or potentially interbreed in nature.” Did you know a camel and a lama were bred to make a calamal? Or is it a comma? One creature from Africa interbred with one from South America and made a new creature, which means all three are, on this definition, ONE SPECIES. Also, lions and tigers can breed to make ligers and tygons, making all four ONE SPECIES. Thus, we can assume that the camels of Africa and the Lammas of South America were descended from the same kind of animal in the not too distant past. Same can be said of lions and tigers, horses and zebras, dolphins and whales, and a whole mess of those beetle species. MANY of the creatures we define as a unique species would, on this definition, NOT be a unique species any more than all of the varieties of domestic dogs. This is why creationists are trying to figure out what borders constitute a KIND. It’s a much more useful category which can make actual use of some of the data the team has been trying to present in favor of evolution.

Evidence for speciation: Speciation in action?
In the summer of 1995, at least 15 iguanas survived Hurricane Marilyn on a raft of uprooted trees. They rode the high seas for a month before colonizing the Caribbean island, Anguilla. These few individuals were perhaps the first of their species, Iguana iguana, to reach the island. If there were other intrepid Iguana iguana colonizers of Anguilla, they died out before humans could record their presence.

 iguana don Evolutionary biologists would love to know what happens next: will the colonizing iguanas die out, will they survive and change only slightly, or will they become reproductively isolated from other Iguana iguana and become a new species? We could be watching the first steps of an allopatric speciation event, but in such a short time we can’t be sure.

I hope you can appreciate how hard it is for me NOT to be sarcastic when faced with this kind of “scientific evidence” for the validity of Evolution. Remember a few paragraphs back when they said this: “the evidence that this sort of process does happen is strong.” Here’s how STRONG it is. “Evidence” for speciation is lizards moving to a new place.  Also, note that this paragraph is about what MIGHT happen in the hypothetical future summed up with “we can’t be sure.” They aren’t even certain that the iguanas will survive let alone do any evolving. Do I need to explain why this isn’t evidence?

I will anyway, with a metaphor.

Imagine the president wants to send troops to start a war with the tiny nation of Stevemenadad. His rationale is thus: “The invasion of Stevemenadad is vital to national security, and here is my evidence. A group of shepherds recently crossed the mountains into Stevemenadad with their sheep. If they grow in number, and sell their wool for guns, and become terrorists, they could threaten the United States. We can’t be sure they will do anything other than raising sheep, but they might.”

Yeah, I’d go to war. What more evidence do you need! They have SHEEP! CNN would totally agree with this move.

On a personal note, if I hadn’t gotten all of this from the Berkley web site, I’d have never believed anyone above a middle school level (And I mean students here, not even the teachers) was involved in any way. I’m starting to feel bad, like I’m picking on a slow kid. But according to the web site I stole all of this from, it was a collaborative project of the University of California Museum of Paleontology and the National Center for Science Education. Yeah, it took a team of people to write the iguana paragraph. They better not have gotten any of my tax dollars for this intellectual travesty.

Join me next week for part 17.



About rentafriend2000
Rocking my 40's with a heart full of love and muffins, science and technology. Jesus loves me and wants me to totally rock! And I am here to help.

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