evolution: hard to fathom instances

[gmalivuk]

Personally, I use the Tree of Life for evolutionary relationships.

http://www.tolweb.org/Eutheria/15997

If the shrews you're talking about are true shrews, rather than tree shrews, then they're more distantly related to bats than humans are. If they're tree shrews, they're more closely related to us than they are to bats. So (and this is admittedly without actually reading the article linked before) I stand by my claim that no nonflying species that's *closely* related to bats has sonar. Which suggests in itself that flight evolved before sonar.

[Izawwlgood]

Some of the more basic, yet hard to fathom instances are paradigms for evolution when you look at them step by step. For example, eyes. It's hard to believe that you could have light sensitive tissue held in a clear medium, behind a light focusing tissue. But if you look at all the examples of light sensitive tissues in the animal kingdom, you can see a progression of encapsulation, covering, focusing, etc.

So some of the things I can't fathom are disruptions to metabolic function, like the development of bladders. Obviously it has to do with body cavity development, but what prompted a development to not simply vent waste products, but to hold them (staving predation sure, but hold them still!)?

[andqso]

The whole notion of sex is always the one that blows my mind. "Hey guys, let's make our offspring more fit by delaying reproduction in order to randomly exchange genetic material!"

But it works.

[HistidineTheCat]

I'd bet bladders developed because of smell - you don't want to announce your every move in life with a loud, smelly exclamation to other species, either predators or prey. Not to mention the health benefits of not pissing all over yourself while you sleep.

I notice that many predators mark their "territory" (wolves, felines, bears, etc.) and that pissing in strategic locations is one way of doing this. Critters that are more likely to be prey, on the other hand, often try to find little hidden pockets away from their normal roaming grounds to do their business (with the exception of deer, who for whatever reason feel it's absolutely necessary to crap in the very middle of hiking trails. I honestly don't know how deer have survived so darn long as a species, what with crapping everywhere and standing in the middle of roads while cars speed towards them). Other prey-critters will piss all over the place when a predator jumps them (ever been scared so bad you wet your trousers?). By then it's often too late to hide yourself, but maybe pissing will discourage the predator or warn your fellow prey-critters.

[HistidineTheCat]

The whole notion of sex is always the one that blows my mind. "Hey guys, let's make our offspring more fit by delaying reproduction in order to randomly exchange genetic material!"

But it works.

Now THAT's a whole new can of worms you just opened there!

[Izawwlgood]

You guys misunderstood me about urine. I'm talking aquatic critters. I'm talking squishy blobs of slug like thingy. But yes, the point is that it's a delayed metabolic activity. Like, ahhh, this ammonia is really bad for me, i'll turn it into urea, and HOLD ONTO IT, until later, when I'm pretty sure theres no predators around. Instead of being like blahblahblah, eating and breathing, breathing and venting ammonia...

[andqso]

Now THAT's a whole new can of worms you just opened there!

Seriously, though. It's one of those things (like evolution itself, I suppose) that seems so obvious to us but isn't really.

After all, it's not necessary for reproduction.

[Interactive Civilian]

You guys misunderstood me about urine. I'm talking aquatic critters. I'm talking squishy blobs of slug like thingy. But yes, the point is that it's a delayed metabolic activity. Like, ahhh, this ammonia is really bad for me, i'll turn it into urea, and HOLD ONTO IT, until later, when I'm pretty sure theres no predators around. Instead of being like blahblahblah, eating and breathing, breathing and venting ammonia...

Keep in mind with aquatic organisms that the idea of osmotic balance comes very strongly into play. Marine organisms are hypotonic to the surrounding environment (so, the ocean wants to steal their water) and freshwater organisms tend to be hypertonic (so the surrounding water either wants to flood them or steal their salts).

Being able to hold your nitrogenous wastes among other things that tend to be filtered by osmoregulatory organs allows you to have a finer control when maintaining water balance and reclaiming salts and nutrients. Though they maybe poison to many cells of the body, they have their uses as well (for example, in maintaining pH balance by carrying excess hydrogen ions and helping the body produce and reclaim bicarbonate).

Fun fact: cartilaginous fishes (such as sharks, skates, rays, etc.) tend to keep their waste in their blood to an extent in order to be relatively isotonic to the surrounding seawater.

[HistidineTheCat]

The sex question is so complicated because there are really several questions. Why necessitate genetic exchange at each generation? Why is this advantageous over cloning? Why do two sexes exist? Why can one sex only mate with the other?

To remain competitive in a nutrient-scarce world, you've gotta trade genes with something. For bacteria, it's plasmids and F+ factors. For most eukaryotes, it's transposons and sex. It's the only way evolution gets beyond simple single-base mutations between cloned generations. The merits and challenges of sexual reproduction are countless and difficult to quantify, to say the least. Some critters reproduce mostly asexually (like the pea aphids that gedtheflayer mentioned), some we've never caught in the act (such as dandelions, actually). But everything's gotta trade genes sometime.

For starters, check here: http://en.wikipedia.org/wiki/Evolution_of_sex . It's a pretty juicy Wiki page, with lots of examples and details and arguments and diagrams. I'd recommend the read.

How did the male/female divide originate? My guess is a species develops two "biotypes", one bulky one that hoards nutrients or makes them available for offspring, one slim and sleek that roams around seeking new colonies. The greater the differentiation between the two biotypes, the more successful the species. Some species of yeast have two sexes that vary only 3 genes. In one sex, pheromone A is secreted, and receptor Alpha is produced; in the other, pheromone Alpha is secreted and receptor A is produced.

[psyck0]

To the OP: Your examples (if used to state that evolution was wrong) fall into the "I can't imagine how it happened, therefore it cannot have happened" method of 'proof', which is completely flawed. Remember that evolution works in tiny, tiny, TINY steps. Imagining such a gradual process can be hard, but when the mechanism is found it will ALWAYS seem astonishingly simple BECAUSE evolution has to work with such small steps. There are no big changes that just spring into being, and so the process HAS to be simple and logical. That is why everyone is so amazed at how evolution can be so 'simple', and yet show such dramatic results.

There are probably a few exceptions that I don't know about/can't remember right now.

Mr. Beck already pointed out that you completely missed the point of the thread. But I gotta also point out that no, evolution is NOT simple. It is not even close. In fact, evolution is the single most complicated thing I have ever come across. If you think it's simple, then you haven't REALLY studied it.

Evolution isn't simply a series of single-nucleotide polymorphisms in coding sequences genetically drifting towards a superior critter. Evolution happens through gene duplications, truncations, rearrangements, and homologous crossovers. It happens through exon splicing, gene sharing, DNA transferral, viruses, and transposons. A significant portion of evolution is shifts in regulation under different cellular conditions. Gene expression at different times in development can drastically change how a critter looks, or it can create entirely new uses for old proteins (gene sharing). These changes can be in any kind of regulatory gene (or a DNA region to which the regulatory protein binds) - look up Hox genes, gap genes, pair-rule genes, segment polarity genes, maternal-effect genes.

There is nothing simple about evolution.

I'd recommend the book Gene Sharing and Evolution by Piatigorsky if you're interested in capturing just a tiny snippet of how complicated evolution is.

I did not miss the point. That's why I added the "if used to state that evolution was wrong" caveat. I just remembered the term for that logical flaw, as well, so I'll add it now- the argument from personal incredulity. Additionally, evolution IS simple. The genetic mechanisms by which it occurs are not (hence "integrated evolution", or whatever the modern term is for studying the genetic basis is, NOT being simple), but you will see a very simple and logical series of phenotypic progressions virtually all the time. And the point of this thread is to talk about the phenotypic progressions, not about the genetic basis, because often we're clueless as to what exact genetic change occured to cause the phenotypic shift.

[Roland Lockheart]

My question: the lamprey. What is it? It is a long rubber tube filled with teeth and an insatiable appetite for blood. WTF!?!?!?

The lamprey, like all parasites, must originally have evolved as an independent organism. Probably once it found a niche parasitizing other animals, a number of traits became unnecessary, and were gradually lost over time as natural selection favored those genomes that sapped less energy growing and maintaining pointless parts and used more to improve its efficiency as a parasite.

Life really sucks when evolution strips a creature down to the bare essentials. I'm fairly certain there are several species of butterfly that emerge from their pupa lacking the parts needed to eat; they are supposed to breed and starve to death. On a similar note, don't the bodies of salmon rot away after they have spawned?

[HistidineTheCat]

I did not miss the point. That's why I added the "if used to state that evolution was wrong" caveat. I just remembered the term for that logical flaw, as well, so I'll add it now- the argument from personal incredulity. Additionally, evolution IS simple. The genetic mechanisms by which it occurs are not (hence "integrated evolution", or whatever the modern term is for studying the genetic basis is, NOT being simple), but you will see a very simple and logical series of phenotypic progressions virtually all the time. And the point of this thread is to talk about the phenotypic progressions, not about the genetic basis, because often we're clueless as to what exact genetic change occured to cause the phenotypic shift.

It's impossible to separate phenotype from genotype. Changes are not always simple or, as you say, "logical", even from a phenotypic standpoint. And that's because of the complex nature of genetics. For example, orthologous genes and paralogous genes evolve by two completely different methods, and each type of evolution will have its own distinct phenotypic progression.

Even when you try to ignore underlying genetic principles just to take a stab in the dark as to how evolution progressed, you'll run into trouble. Drastic evolutionary changes often happen because of changes in environment, causing latent gene functions to become realized in a population. And phenotypically inactive genetic shuffling (often caused by transposons) can cause speciation before there is any sort of visible evolutionary change.

And the phenotypic changes that you can see are often not progressive. I can think of three such examples right off. 1) Virus/transposon-induced genetic transfer from one species to another can bring a totally new set of genes into a population. 2) Some organisms (plants in particular, though I'll bet there are lots of others) can acquire entirely new chromosomes that weren't there before. Strawberries are octoploids, bananas are triploids, corn is (I think) pentaploid. Many wheats and grains are a result of hybrid chromosome additions (two species' chromosomes put into one organism). Changes in ploidy level almost always come with large differences in phenotype. 3) An organism can evolve an entirely new gene or find new function for an old gene such that an entirely new ability or phenotype develops rapidly, such as Lenski's E. coli evolving citrate metabolism.

The idea that all evolution occurs "gradually" and "progressively" and "logically" is an outdated one reminiscent of Lamarckianism. And I think the discussions in this thread prove that, by bringing up all sorts of evolutionary changes that simply couldn't be gradual or logical. That's the point of the thread, really, is to think of the most ridiculous and illogical evolutions. So to generalize that evolution is gradual and logical is counterproductive.

[gmalivuk]

Except, if you've read the thread, you'd see that for most of the changes brought up, a gradual and logical progression *can* be imagined. And in some cases (like the eye) there are enough extant examples to suggest that this really is how it happened in the past.

[qetzal]

How about parasites and infectious agents that change their host's behavior?

For example, there's a fungus that infects certain ants, causing them to crawl to the top of a plant & clamp on before they die. The fungus then sends fruiting bodies out through gaps in the ant's cuticle, to disperse its spores. Having the ant at the top of the plant gives wider spore dispersal. (See http://schaechter.asmblog.org/schaechte ... -plan.html)

Then there's the parasitic wasp that lays up to 80 eggs in a certain species of caterpillar. Of course, the caterpillar is eaten alive from the inside as the wasp larvae grow, but it doesn't die even after the larvae burst out of its body. Instead, it becomes a zombie guard, protecting the larvae as they pupate on the branch next to (what's left of) the caterpillar! If anything comes near, the caterpillar whips its head back and forth, presumably discouraging predators that might otherwise eat the pupating wasps. (See http://scienceblogs.com/notrocketscienc ... yguard.php)

[Izawwlgood]

HOLY CRAP PARASITES! Sweet zombie jesus they terrify and amaze me. Go read Carl Zimmers Parasite Rex NOW! It will horrify and astound you! Parasites travel through entire biomes, which is incredible in and of itself.

And those wasps that lay their larvae in catipillars... They dont' just lay 'turn to adult wasp' larvae, they lay about a dozen different KINDS of larvae, some that supress the hosts immune system, some that labotomize the host, some that act as yolk for other larvae and are themselves EATEN (life sucks), and finally, some that grow into adult wasps...

The more biology I learn, the more I find support for the notion that "Nature does it better". Find me an engineering success humans have had and nature has probably solved the problem as well.

[Mr_Rose]

The more biology I learn, the more I find support for the notion that "Nature does it better". Find me an engineering success humans have had and nature has probably solved the problem as well.

And done it in a way that is self-repairing, self replicating and probably largely independent of other mechanisms (except in the broadest sense of all life being dependent on other life, mostly plants).
Although, possibly not bridges. We're really good at those, but even army ants and other mobile colony creatures generally just make pontoons rather than real bridges.

[Roland Lockheart]

The more biology I learn, the more I find support for the notion that "Nature does it better". Find me an engineering success humans have had and nature has probably solved the problem as well.

Get a complex organism to survive in the vacuum of space? Not that getting to space was a problem that needed solving...

[alexh123456789]

The more biology I learn, the more I find support for the notion that "Nature does it better". Find me an engineering success humans have had and nature has probably solved the problem as well.

Guns. Nature has been trying to kill stuff right since life started, but humans still win that contest

[Izawwlgood]

Read up on the Bombardier Beetle. There's also a caterpillar that projects it's feces a couple meters away from itself (the thing is maybe 2 inches long) by exploding blood vessels by it's anus. Yes. Exploding. Blood vessels. Anus.

I wasn't referring to scale projects (theres no Hoover Dam of the animal kingdom), but just about everything we've tried to do, nature has a solution for.

Also, a number of organisms have been found to survive the rigors of vacuum, including dealing with radiation hundreds of times what roaches can sustain.

[crowey]

Although, possibly not bridges. We're really good at those, but even army ants and other mobile colony creatures generally just make pontoons rather than real bridges.

inital stages of spiderwebs? Not quite right but the main principles of suspension bridges are there....

The more biology I learn, the more I find support for the notion that "Nature does it better". Find me an engineering success humans have had and nature has probably solved the problem as well.

Guns. Nature has been trying to kill stuff right since life started, but humans still win that contest

cnidarian nematocysts are so awesome.

[Roland Lockheart]

Read up on the Bombardier Beetle. There's also a caterpillar that projects it's feces a couple meters away from itself (the thing is maybe 2 inches long) by exploding blood vessels by it's anus. Yes. Exploding. Blood vessels. Anus.

I wasn't referring to scale projects (theres no Hoover Dam of the animal kingdom), but just about everything we've tried to do, nature has a solution for.

Also, a number of organisms have been found to survive the rigors of vacuum, including dealing with radiation hundreds of times what roaches can sustain.

I find this interesting, do you know any examples (of organisms that survive in a vacuum)? If I had to guess I would probably say some sort of mollusk or insect.

[Thisisnotausername]

The appendix, cotton plants, and sociologists. I mean, wtf.

[gmalivuk]

I find this interesting, do you know any examples (of organisms that survive in a vacuum)? If I had to guess I would probably say some sort of mollusk or insect.

I would guess something much, much smaller, actually.

[gedtheflayer]

I find this interesting, do you know any examples (of organisms that survive in a vacuum)? If I had to guess I would probably say some sort of mollusk or insect.

I would guess something much, much smaller, actually.

I imagine that since anaerobic bacteria can produce energy without access to oxygen, they might survive for a little while in a vacuum. However, the problem comes when you think about naturally occuring vacuums. The big one is space, which in addition to the vacuum problem has no gravity to speak of and probably not enough organic material floating around to sustain most life. Then again, that doesn't rule out chemosynthetic bacteria, such as those found in underwater geothermal vents. So, it is reasonably possible for bacteria to live in space, if they have a proper chemical source (perhaps they could secrete an enzyme to break down their rocky "food", but that would bring up the problem of getting enough peptides to sustain it).

Makes me wonder if anyone has done cell biology experiments in zero gravity conditions.[/off topic]

[andqso]

Makes me wonder if anyone has done cell biology experiments in zero gravity conditions.[/off topic]

What do you think we're spending so much money on the ISS for?

[Izawwlgood]

No organism thrives in vacuum, but many organisms can survive it. endospores have been found on protected portions of space craft that survived exit, vacuum, and then reentry, and a handful of experiments I've read about demonstrate that vacuum is not sufficient to sterilize surfaces.

Theres a species of archaea i recall reading about that has four sets of it's genome, and constantly copies back and forth between the sets, and can apparently survive laughable amounts of UV radiation. I'll have to scour my micro book and see if I can find it again, I don't mean to throw anecdotal, non-cited info up.

But yes, for added shits and giggles, look up Archaea. The entire kingdom is full of organisms that survive the most unbelievable environs. Areas so salty they can't survive brine because it's got too much water, the deep ocean sulfur vents that spew lead melting temperatures, extreme pressures, zero sunlight, zero oxygen... tons of other elements have been utilized as an electron acceptors (copper, iron, sulfur, magnesium!), meaning life can find itself into a host of areas that would otherwise be considered toxic.

Many mines have a problem with archaea blooms gumming up their waste water lines.

Also, the ISS is a complete waste. It is far cheaper to send up small satellites with the microexperiments in mind, then to routinely keep someone non sustainable on the ISS. I'd rather see a satellite 5 ft on a side stuffed with petri dishes then that monstrosity.

[Tac-Tics]

Evolution is to science as democracy is to government. It's the worst theory on why life is the way it is.... except for all the others.

[Roland Lockheart]

I find this interesting, do you know any examples (of organisms that survive in a vacuum)? If I had to guess I would probably say some sort of mollusk or insect.

I would guess something much, much smaller, actually.

I imagine that since anaerobic bacteria can produce energy without access to oxygen, they might survive for a little while in a vacuum. However, the problem comes when you think about naturally occuring vacuums. The big one is space, which in addition to the vacuum problem has no gravity to speak of and probably not enough organic material floating around to sustain most life. Then again, that doesn't rule out chemosynthetic bacteria, such as those found in underwater geothermal vents. So, it is reasonably possible for bacteria to live in space, if they have a proper chemical source (perhaps they could secrete an enzyme to break down their rocky "food", but that would bring up the problem of getting enough peptides to sustain it).

I thought we were talking more complex organisms, but yes, space dwelling bacteria isn't hard to imagine at all.

[Heisenberg]

The whole notion of sex is always the one that blows my mind. "Hey guys, let's make our offspring more fit by delaying reproduction in order to randomly exchange genetic material!"
But it works.

The reason it works is because the exchange of genetic material is not random. Initially, organisms DID randomly exchange genetic material, just by bumping into each other.
WNYC's Radiolab says:

Steve Strogatz, an applied mathematician at Cornell, tells us about a radical theory that says that way back at the beginning of life, 3 billion years ago, life was a big commune of gene swapping. Nigel Goldenfeld, one of the scientists who came up with this theory, says that the idea of different species, and consequently Darwinian evolution, simply didn’t apply for the first billion years of life on Earth.

For a long time, bacteria would swap genes, but at random. So I might get Steve's tolerance for sunlight by bumping into him, but I'd also get John's allergies to sulfur by trading with him. Finally, bacteria developed membranes harder to penetrate, and got antisocial. After this, somebody thought up sex, which only passes on the good genes, since the bad-gened individuals are less likely to reproduce. It slows everything down significantly, but it allows species to evolve.

[erik542]

I'm having a debate on another site with a creationist. I've more or less been challenged to explain the ten commandments. I did the real obvious explanation of murder, and a passable to them explanation of adultery. What I am having problems with is finding a good explanation for thievery. The best I could think of is some food source thing that felt really awkward. Anyone know of a good one?

[Izawwlgood]

Vampire bats are known to share bloodmeals with cavemates to allow a mate to survive another night if they haven't found a meal. Vampire bats can survive I guess 36 hrs without a meal, so sharing of meals is very important for the overall group survival.

Bats that cheat are promptly kicked out of the commune.

[Charlie!]

If a group all has the same "cooperation" gene, that group as a whole is more likely to survive and spread their genes than some rabble that can't cooperate. Even when there's not a direct personal benefit, there's a benefit to carriers of your genes, which is sufficient to make it selected for.

[tantalum]

You could cite some sort of altruistic evolution - The Selfish Gene, among many other books, explains how altruism could have arisen via "selfish" evolution. Hamilton's law is a good place to start.

[tantalum]

Something I've always been curious about is why humans understand music the way they do. What is it about chord progressions that evoke such emotions in us? Why does a minor key evoke completely different feelings from a major key when the only thing different is the pitch frequencies of three notes, and only by a tiny bit? How are humans able to distinguish the tonal center of a piece? Why do some people have perfect pitch?

[Izawwlgood]

Musical progression is mathematical in nature, and I recall reading somewhere that by establishing a base line frequency, and progressing away from the frequency, the human sensorium seeks a sense of completion (Think Golden Ratio perhaps, we like to see symmetrical forms or completed sets). Therefor, progressive musical forms provide a sense of tension and release.

Or something.

Altruism is something that isn't really ever found. It doesn't exist. Cooperation is entirely different, and is found across the animal kingdom. Cheating is heavily discouraged.

[qetzal]

I'm having a debate on another site with a creationist. I've more or less been challenged to explain the ten commandments. I did the real obvious explanation of murder, and a passable to them explanation of adultery. What I am having problems with is finding a good explanation for thievery.

Wha???

You mean, the creationist says evolution is false unless it can explain why the Bible says Thou Shalt Not Steal?

If that's what s/he's insisting, don't even bother! Next s/he'll insist you explain how evolution accounts for Jesus's resurrection.

[gmalivuk]

If a group all has the same "cooperation" gene, that group as a whole is more likely to survive and spread their genes than some rabble that can't cooperate.

Though that's true, it's not evolutionarily stable. Because a single individual without that gene can come in and take advantage of the altruism of the rest of the group, and then do better reproductively than the lot of them.

[Charlie!]

If a group all has the same "cooperation" gene, that group as a whole is more likely to survive and spread their genes than some rabble that can't cooperate.

Though that's true, it's not evolutionarily stable. Because a single individual without that gene can come in and take advantage of the altruism of the rest of the group, and then do better reproductively than the lot of them.

Yeah, I guess you'd need some sort of reciprocity as well.

[Mr. Beck]

Read The Selfish Gene, and everything about altruism suddenly make a boatload of sense.

[gmalivuk]

It also might get fewer people to enter discussions about evolution with "If a group does X...".

Group selection doesn't really happen for genetic evolution.