Very Serious Reflection Post

 Hello, and welcome to my Very Serious Reflection Post, where I Reflect Very Seriously on all the Crazy Science that I have learned over the past four weeks. Because as fun as this blog my seem, it is in fact a class assignment and I am Legally Obligated to be serious on it at least once a month. 

Okay, not really. Sorry y'all, y'ain't getting rid of my shenanigans that easy!

I would like to deviate from my regularly scheduled Screaming About Science posts, and instead scream over Learning  About Science. Bc y'all, we be learnin' up in here. 

I started the semester with a rather workable idea of evolution, save for one misconception: time. Unlike my second blog post claims, evolution doesn't have to take generations and generations and generations of arduous time. Things can change in just two generations! And in some organisms (like bacteria), that amounts to maaaaybe a couple of hours' time. Like, bruh. Bruh. 

Luckily for me, Michi didn't laugh in my face over my misconceptions, and continues to be a stellar teacher. My biggest struggle in this class is coming up with blog posts that don't make me want to die from the boredom of regurgitating bland science. I want my science snazzy, thank you very much. 

Okay, jokes aside, I did have some trouble understanding how the mechanisms of DNA replication relate to evolution - but only because I didn't know the mechanisms of DNA replication. That was...awkward. Don't like lookin' stupid over here. But hey! Now I'm suffering through that unit of Modern Genetics, so it's a win-win. Ya girl is ON IT. 

As for the remainder of the class, I'm pretty pumped to see what else we got on the docket. I've never learned about evolution beyond the classic Darwin-and-Mutations stuff, so...who knows what's next?! I, for one, am hoping to discuss which animals are likely to evolve sentience and inherit the earth after humans have died off. My money's on corvids. 

Course, if they decide to get a head start, then I for one would welcome our new corvid overlords. 

Edit: I've made and found a lot of memes for the class, so here are some my favorites so far. Feel free to steal and use. 

Selection OR Not?!

Good Evening and Welcome to the latest gameshow craze sweeping the nation! We've got science, we've got retro music, and we've got eighties-techno-fonts, it's-

This week on Selection Or Not?!, we explore one of most vital and yet little-understood facts of evolution: mutations! We all know they cause evolution, but do mutations evolve themselves? Does the rate of mutations vary and evolve? Well, let's ask our qualified expert! 

...This just in, we do not have a qualified expert. So instead, you'll get the unqualified musings of your lovely host. 

As all you lovely audience members know, evolution is based on change. You also know that natural selection is one of evolution's driving forces! But how do we know natural selection is happening? Well let's ask Darwin, the first man to ever conceive the idea, about his 5 requirements! 

...This just in, Darwin apparently passed away several centuries ago. Instead, let's consult our lovely and yet increasingly confused host! 

For our new audience members, here's how the contest works: We put a trait through Darwin's 5 postulates of Natural Selection, and if it meets them all, then it's selection! Now, make your predications about this week's topic: Mutation Rates!

But what are Darwin's 5 postulates? Well, I'm glad you asked! First, there must be a fight for survival between individuals. Second, only some individuals can survive this fight. Third, individuals must exhibit variation. Fourth, some of that variation must be heritable. And five, some forms of variation must be favored in the fight for survival between individuals. 

This should all culminate with the individuals who have the favored variations being the ones who win the fight for survival! 

You know the drill! If it passes all five postulates, then natural selection could be acting up it. Are you ready? Then let's play-

First up, Darwin's first and second postulates: the Fight for Survival and There Can Only Be One. Is there competition between individuals with different mutation rates, resulting in some organisms not surviving? 

And the answer board says...

Definitely! Organisms more prone to mutations are more likely to develop harmful traits that prevent them from surviving. Organisms with lower mutation rates will see less harmful mutations, resulting in better survival. 

Next question! Do organisms exhibit variation in their mutation rates? 

And the answer board says....

The majority of mutations arise from errors in genome copying. Genes are copied by a protein that is also coded for in the genome! If that copying code varies, organisms will have a variety of accuracy when it comes to copying their DNA. That's variation! 

Three down, two to go! Fourth: is the variation in mutation rate heritable? 

Answer board says...

Yes! The protein for genome copying (called DNA polymerase) is heritable, because it is encoded for by genes! Whether a parent makes effective or mistake-ridden DNA polymerase, they're going to pass that trait down to their kids. 

Fifth and Final question! Some variation in mutation rate is favored and leads to better survival. Are there circumstances were a high or low mutation rate would be adaptive? 

Science (and your clueless host) says yes! 

High mutation rates could be adaptive in environments that change frequently - an abundance of mutations would mean that beneficial mutations come about more quickly, and thus a population will adapt faster to environmental change. 

Low mutation rates might be adaptive in environments that are very steady. Mutation is almost always negative, so if an organism already has a highly adapted form then their mutation rate might drop so as to minimize unwanted variation in the face of a steady environment (see how crocodiles and sharks have gone unchanged for millions of years). 

Hey, we made it! Looks like mutation rate can be acted upon by natural selection! Congratulations to all who played along. Join us next week for another episode of-

Weather Forecast: Sharks

Much like the weather, natural selection is always happening. And much like the weather, we don't notice it until things start to change. 

Picture an average winter day. It doesn't matter what you picture - just pick something. I think of clear skies and snowy fields, just cold enough to make me want some hot chocolate. What I don't picture is below-zero weather bad enough to make me type this while laying under three blankets. 

But here we are. 

Natural selection is a lot like the weather. Weather happens all around us, all the time - but it's so subtle that we don't really notice until something makes an abrupt change. If the weather is like natural selection, then climate change is like evolution. It seems random, startling, and abrupt - until we look closer. 

Of course, not all weather is destined to lead to climate change. Just like not all natural selection is destined to lead to evolution. Weather can hold steady patterns for hundreds of thousands of years, each season reinforcing the rhythm of small changes. In the same way, natural selection isn't always gunning for some new and outrageous design - sometimes it simply holds steady, reinforcing the pattern that already works so well. 

I mean, look at sharks. 

https://www.mendotraintony.com/sharks-along-the-mendocino-coast/

God, I love sharks. Sharks evolved around 450 million years ago ("Geologic Time", Martin). Four-hundred and Fifty. Million. Years. That's 200 million years before the first dinosaurs. And yet the earliest sharks looked surprisingly similar to the ones swimming our modern oceans. 

https://www.nhm.ac.uk/discover/shark-evolution-a-450-million-year-timeline.html

If you showed that to me and said "Wow, look what some scientists saw off the coast of California!", I wouldn't think anything of it. Except maybe to make fun of its derpy little face...

Anyways, my point being, sharks haven't changed much over 450 million years! They've diversified and evolved into specific niches, but their plan-of-action for survival is pretty much the same: swim around and eat things. If you want to watch shark evolution, you're going to be waiting for a long time. 

But we're not talking about evolution. We're talking natural selection. And even though sharks haven't evolved much lately, natural selection is still in action. Because sometimes, like the weather, natural selection doesn't have big and dramatic events; sometimes it just maintains the status quo. 

Natural selection has made sharks into something simple and efficient. That countershading? That big propelling system and that pointed nose? Those traits work. Sharks aren't evolving, because they don't need to; natural selection has already put them into a well-adapted form. All selection is doing now is reinforcing that form, tweaking it by little bits, making it better but really not changing much at all. 

Because it works. 

Natural selection isn't striving towards some higher goal. It's not trying to make tool-using or bipedal sharks. Natural selection meanders towards forms that work well in a specific environment, evolving over time to make an organism really good at surviving and reproducing. And if natural selection has 450 million years of finding a good form, that form is going to be pretty. damn. good.  

Sharks don't need to evolve, they just need to maintain their current form. So that's what natural selection is doing. 

Of course, there are other forces of change outside of natural selection. Anything that alters the genes frequencies in a population is one of those "forces of change". Big disaster kills off a bunch of sharks? The sharks that are left might randomly have smaller fins. Then all the offspring of the survivors will also have smaller fins. It's not natural selection, it's just chance. This is called the bottleneck effect. Chance also plays a factor in something called genetic drift - where some traits become more common out of pure coincidence, and not because they're better for survival or reproduction. And let's not forget the importance of choice: sexual selection can also lead to evolution - even evolution that seems counterproductive! Colorful birds are way easier for predators to spot, but boy howdy do they get the ~ladies~. All of these forces can cause change, and even lead to evolution, despite the fact that they're not events of natural selection and don't always lead to better-adapted forms. 

Long story short, things in nature aren't simple. We can't always see what's going on right in front of our eyes - but that doesn't mean it's not there. You don't need massive change for something to be happening. So go outside and open your eyes - and try to see not just the big things, but the small things too. 

Or maybe don't. It's like, -20 F out there. 

Birds Don't Go To The Gym

Listen. I love the gym as much as the next person. And by "I love the gym", I mean I hate the gym. I do not do the sports-ball, I do not enjoy repetitive body torture, and the only place I run is to the dinner table. I like to think that Charles Darwin was of a similar mind. 

Let's not spend too long on that shoddy metaphor, and instead focus on what I mean by it. Darwin it rather famous for his unorthodox use of the word "fitness". In high school biology classes, most of us are probably guilty of taking this word the wrong way. I, for one, really enjoyed picturing buff-as-hell finches. Like, absolutely swole. Just ripped. 

https://www.reddit.com/r/birdswitharms/comments/9p08l1/the_mighty_muscle_bird_got_an_upgrade/

If I had to see it, so do you

But finches don't go to the gym (thank GOD), and Darwin wasn't implying that they do. Darwin's version of "fitness" doesn't care how much you can bench (sorry, frat boys) - it cares about how much you have sex (...never mind). 

Okay, immature jokes aside, Darwin's version of fitness really does care about reproductive success. In fact, that's what it's meant to describe! Biological fitness describes how good an organism is at surviving and passing down its genes to the next generation. Obviously this takes thousands of different forms - from being strong enough to fend off competitors to being fast enough to escape predators to being drought-tolerant enough to survive the summer. 

So...fitness is less an episode of America Ninja Warrior and more like an epic crossover of Man vs Wild and the Bachelor. 

....damn, now I kinda want to watch an epic crossover of Man vs Wild and the Bachelor....

Anyways. That's our definition of fitness. Actually measuring it, though, that can be a lot harder. Trying to measure fitness is like trying to measure how good of a kisser someone is - it's entirely subjective to the situation. You see, fitness isn't the same everywhere and everywhen. It's dependant on the environment than an organism is in. 

That's...confusing. Yeah, I'm confused. Example time!

Let's try to measure the fitness of...moths. How do we feel about moths? I like moths. Let's do moths. 

OKAY!

https://www.icr.org/i/wide/peppered_moth_wide.jpg

Meet the peppered moth, also known as Biston betularia. Recognize it? I'm not surprised; their adaptation story is a staple in most biology textbooks. But in case you haven't heard it, I'll do a quick recap:

As you can see, this moth has two main forms (called morphs): a natural white morph (right) and a dark mutant morph (left). Around the industrial revolution, the mutant form became a lot more common, to the point where the normal white forms were hardly seen at all. This is because all the ash from the factories turned the local trees from white to black. White moths used to be "more fit", because they were better camouflaged against the white trees. But when the trees turned black, the black moths became "more fit" because they matched the new environment. 

See what I mean about the importance of environment? The darker moths weren't stronger or faster or better at flying away from birds. They also didn't do anything to become better at those things. It was their environment that changed the rules, reversing which color of moth was suddenly better at surviving and reproducing. And since more fit equates to better at surviving and reproducing, it was a sudden shift in which moth type was more "fit". 

But how do you quantify this? How do you assign a "fitness score" for a dark moth versus a white moth? Well, you could measure how many of each color survive. But that's more a measure of their trait (color) than their fitness as individuals. My best guess would be to measure their reproductive success. 

Let's take a population of hypothetical moths - some dark and some light. And then we chuck 'em in an outdoor enclosure where they can be eaten by birds. Then we wait, and watch, and eventually count how many eggs each moth produces. Then we wait for those eggs to grow up, and measure how many survive into adulthood and produce their own eggs. The number of moths that survive and reproduce could be used as a direct measure of their parent's fitness, since it was their parents who gave them the genes to survive. 

Theoretically, an experiment like this would show us which color is "more fit" for the environment we put them in. If we chuck 'em in an outdoor enclosure full of white trees, we're probably gonna see that the white moths produce more successful offspring. If we chuck 'em in an enclosure full of black trees, we're probably gonna see that the black moths produce more successful offspring. 

...I wonder what would happen if we chucked 'em in an enclosure full of brown trees......

Anywho. Unlike many of my other blog posts, I am not confident on my answers in this one. But it seems logical to me that if fitness = how much of your genetic material is in the next generation, then you can measure fitness by measuring how much of the next generation has your genetic material.

But, I digress. I'm gonna go google Man vs Wild and the Bachelor crossovers. And try to scrub muscle bird out of my brain. 

Lamarck shouldn't be so La-Marked

 Anybody who's taken a basic biology class learned about Jean Baptiste Lamarck - whether they remember it or not. Lamarck, like Darwin, proposed a theory of evolution. But unlike most scientists we learn about in school, Lamarck didn't get famous for being right. He got famous for being wrong. 

Really, though, we need to cut Lamarck some slack. He was the first person to even conceptualize the idea that organisms might change through time. And he did his work in 1801, when we knew jack-all about real science. I mean, people still thought cocaine made a good medicine. The first fossil collections were just getting started. Creation myths and religion reigned supreme over logical thought. Can we blame Lamarck for getting a few things wrong?

Okay, so what exactly did Lamarck get wrong? Well, first we should talk about what he got right. 

Lamarck was the first person to formally theorize that life is not fixed - an impressive statement considering that most people of the time hardcore believed in the literal interpretation of the Bible's creation myth. So. One point to Lamarck, for not being a basic b****. 

Lamarck also proposed what causes life to change: their environment. Lamarck theorized that organisms change when their environment changes, and that these changes help an organism better survive in their altered environment. This was basically the first theory of adaptation, so...Two points to Lamarck!

And then Lamarck suggested that a man could grow wings by throwing himself off a building and trying to fly. 

Okay, not really. "Man can fly is he really wants to" is an exaggerated version of Lamarck's theory for how evolution happens - which, if you couldn't tell, he got wrong. Lamarck theorized that an organism changed when its environment forced it to use its features in a novel way. For instance, if trees grew taller, giraffes would make their necks slightly longer by continuous stretching. Their offspring would then get longer necks, and then stretch their necks even higher. Over several generations, the small stretches would accumulate to make the neck several feet longer. Thus, through continuous and novel use, giraffes got longs necks. 

It's easy to laugh at this theory, but I'd say it was pretty damn good for Lamarck's time. Remember - cocaine medicine. Lamarck correctly identified that most changes happen in small increments over time, rather than in massive shifts. He also correctly identified that traits needs to be passed on to subsequent generations, or the change would be restricted to the first organism it appears in. That's two more points for Lamarck right there.

So really, the only thing our dear Lamarck missed the target with was how changes come about. Changes don't happen because of need in an organism's life, but spontaneously in their genetic code before their birth. It's other forces that drive some mutations forward and keep other changes back. When you put yourself in Lamarck's 19th-centaury shoes, it's pretty easy to see why he got this wrong - no one had discovered genes or methods of inheritance! That wouldn't come until 1865, when Gregor Mendel (a monk with a serious pea passion) published his discovery of "heritable factors" in pea plants. Even then, it took a while for Mendel's work to be connected to the theory of evolution. Looking back on it all, Lamarck got a lot more right than he got wrong. 

Well...kind of. Lamarck got some other things wrong, too. He believed that evolution was gearing organisms from "simpler forms" to "more complex forms", when we know today that evolution just prompts organisms to survive and reproduce in whatever form is best suited for the job. He also argued that life had many "starting points", as evidenced by the existence of microbes, who hadn't yet had the chance to evolve into "more complex forms." Today we know that life had a single point of origin - and we see evidence for that in the identical genetic code every living thing carries. 

But despite the cocaine medicine and religious confusion, Lamarck still got four points - and that's more than I honestly expected from a guy who thought fashion involved high-waisted tights and top hats. While I do love laughing at some of his ideas, Lamarck gets more derision than he deserves. 

I man, come on. I'd hate for my mistakes to be immortalized forever. 

Why Does Alligator Taste Like Chicken?

 

    I'm a picky eater - especially when it comes to new food. Of course, this means that my friends and family make a game of who can cajole me into eating the strangest dish. One of the strangest things I've ever tried was alligator. And what they told me was true - it did taste like chicken. A slightly fishy, slightly tougher chicken.

    Of course, now I'm left with the obvious question: why does alligator taste like chicken? I mean, what the heck? What do a chicken and an alligator have in common? One lays in swamps all day, hissing like a cobra and sunbathing like a model. The other struts around pecking at the dirt and yelling. Don't get me wrong; I know chickens are bloodthirsty little b*tches. But, really? Can a chicken even hold a candle to an alligator? 

Yes. Yes they can. 

To our modern eyes, the American alligator (Alligator mississippiensis) and the domestic chicken (Gallus gallus domesticus) are about as different as two species can get. One swims, one flies...ish. One is big enough to kill a human. The other is frequently kept as a pet. But what we don't know, and what Darwin figured out, is that two species never exist completely independently. Even a chicken and an alligator are connected by a common ancestor. And for these two, that ancestor might be more common than you think. 

First of all, we should establish that birds and dinosaurs are nearly one and the same from an evolutionary standpoint. As pointed out by paleobiologist John Ruben in his paper Paleobiology and the origins of avian flight, scientists are pretty convinced that birds and dinosaurs share an evolutionary line. BUT, if we go even further back into evolutionary history, we'll see that birds, dinosaurs, and crocodilians (which includes crocodiles, alligators, and gharials) all share a common lineage known as archosaurs (which, bonus points, also includes pterosaurs). 

Archosaurs as seen in the fossil records obviously aren't around anymore. Fossils suggest that archosaurs diverged into two groups about 250 million years ago. One group became crocodilians and other similar, but now extinct, lineages, while the other group went on to produce lineages of dinosaurs, pterosaurs, and birds. 

Now, I know you're asking, "Big deal, Madison. They diverged, like, ages ago. There's no way that's relevant now!" But you're wrong. 

Scientists used to think that the bird-like group that became dinosaurs, birds, and pterosaurs lost their connections to crocodilians pretty quickly, instead rapidly evolving into the familiar dinosaur forms known today by children everywhere. After all, early bird-line archosaurs (like Marasuchus, Dromoeron, and Lagerpeton, according to an article on this subject published by EurekaAlert in 2017) appeared small and dinosaur-like. But a newly-categorized fossil has shed different light on this old view. 

Teleocrater rhadinus

Meet Teleocrater rhadinus, the earliest known member of the bird-like archosaur lineage. It's not a direct relation to dinosaurs or birds - more like a strange, still-slightly-crocodilian cousin that you'd try to avoid at family gatherings. According to the authors of the paper published in Nature, Teleocrater isn't exactly like a dinosaur  (and thus a bird) or a crocodilian. It's somewhere in between, with the jaw muscle morphology of bird-like archosaurs but the splayed, hypermobile ankle joins that give crocodilians their characteristic gait. Teleocrater proves that bird-like archosaurs initially retained a lot of crocodile-like traits from the common ancestor of all archosaurs, and gained bird-like traits step by step over a longer period of time. In layman's terms, Teleocrater is the "missing link" between dinosaurs and the common ancestor they share with crocodilians. This crazy-looking thing is why alligators and chickens taste similar. 

Now I know you're asking, "Sooo...if I go kill a lizard and eat it, will he taste like chicken too?" And honestly, I don't know. Go try and report back on your findings. 

Or, on second thought, maybe don't. Reptiles like snakes, lizards, turtles, and their common ancestors aren't considered archosaurs. And yes, that means crocodilians are more closely related to birds than other reptiles. So I wouldn't chance it when it comes to lizards. 

So would Teleocrater taste like chicken? Maybe. Until we invent a time machine, I can't answer that. But I can definitely tell you that alligator doesn't taste like chicken. Why not? While the evolution of birds is still hazy, most scientists concur that crocodilians came first by at least 150 million years.

So really, alligator doesn't taste like chicken. Chicken tastes like alligator. 

Source articles, if you're so inclined: 

https://www.eurekalert.org/pub_releases/2017-05/kfu-pmi053117.php

https://www.eurekalert.org/pub_releases/2017-04/fm-ed041017.php

https://www.eurekalert.org/pub_releases/2014-12/uoc--srg120514.php

https://www.sciencedaily.com/releases/2010/02/100209183335.htm