e been playing waaaaay too much Jurassic World: the Game. No, that isn’t the reason I haven’t updated anything. That, well, I might be moving my blog to Tumblr, or at least another account. We’ll see, but it's pretty likely that this will be a massive, three-part "grand finale" of sorts.
Anyways. Jurassic World. Fun ride of a movie, which is amusingly about an amusement park. I want to take a D-Rex home. Working on it in the game. D-Rex should have looked more freakish if they put cuttlefish in there - c’mon, at least give us the neat W-eye! My general thoughts on the movie will get their own blurb later. Also, for whatever reason, JW and JP both hate frogs, even though it’s probably entirely unwarranted.
Why? Because, from the get-go, dinosaurs could reproduce without a male.
|Who's the man in this, again?|
Read that sentence again.
Read that sentence three times if you have to. Let it sink into your brain: even without as much genetic meddling that Jurassic Park had, from the get-go, the potential for every dinosaur on the island to reproduce asexually, and then sexually.
Now, here’s my disclaimer: Crichton was largely using the frogs for genetic freak purposes. The whole point of Jurassic Park was that, maybe, there are some buttons science shouldn’t push. The frogs are the bad guys for art rather than any logical reason. I realize people back then didn’t know precisely how close birds were to dinosaurs, but there’s still no reason to use frogs other than HERPDERP SCIENCE EFFED UP. Use lizards. Or chickens. Science can get those very easily.
So, just how is this possible, anyways? What could prompt natural dinosaurs to reproduce without a male? It’s all genetic…as nature intended?!
I’m tempted to assume that most people reading this have taken basic biology in high school, sex ed, or both. All you really need to know for this is that human (and other mammal) females have XX sex chromosomes, and males have XY. Women are the only sex that could possibly reproduce without a male, but in mammals, that’s pretty much unheard of, and all of the offspring would be female clones of the mother.
That is not the case with the rest of non-mammals.
For many other creatures, including everything from butterflies (yes, butterflies are more like birds in this regard), to lobsters, to chickens, sex is determined by a system called “ZW.” What this means is that the males are ZZ (no, not ZZ Top, but if that helps you remember, go for it) and the females are ZW.
That thing, with the females having two different letters (heterozygous), changes everything. Parthenogenesis, AKA “virgin birth” if you’re not a fan of Greek, occurs with a female egg effectively impregnating itself. It has been known to occur in lizards (most notably whiptail lizards, who are only female, and Komodo dragons), snakes (boas, Burms, and Brahminy blind snakes - again, that last one is only female) and a special breed of turkey literally bred because people thought this parthenogenesis thing was just too darn cool. No, chickens laying eggs by themselves doesn’t count; the eggs you buy at the grocery store are effectively chicken periods. Enjoy your Dunkin Donuts breakfast sandwich!
ZW animals can produce parthenogenically by either all-out cloning or half-cloning. A full clone is exactly that: a perfect clone of the mother. The half-cloning, however, includes only half of mom’s genes - twice over. For ZW, that means one letter gets repeated.
|Umm...girls? Your lesbian sex is legal, now. Everywhere.|
Remember what’s special about ZW: the male has ZZ. Through half-cloning, a mother lizard can create an entire clutch of males. They’re almost identical to her in every way except sex. Then, they can just go ahead and do it again with mom, or maybe even the odd WW females. ZZ Top will always be male. I’m sure they’re thrilled to be in a lesson about dinosaur sex.
Parthenogenesis gets less frequent down the evolutionary “line,” but it’s not like dinosaurs grew out of it. If you must make evolution linear, dinosaurs are like a link between reptiles and birds. We’ll get to crocodiles; for now, well, birds are capable of it, too.
BUT…they’re not as good at it.
Parthenogenesis in birds usually results in duds. Either the eggs aren’t quite fertile, embryos die early, or the offspring have reduced fertility. An exception occurs in turkeys, who, for reasons not entirely clear, have mastered the art of giving birth without a dad. These are all ZZ males, who have then been rebred to virgin-birthing females in order to create a more stable strain, and eventually a breed. These ZZ Toms (the joke will not die as I write it!) are almost indistinguishable from your average turkey.
|If half-female, half-male chickens are possible...imagine a raptor like that.|
This is just the tip of the genetic weirdness iceberg possible without the frog. ZW is also capable of the weird chimerism called “bilateral gynandromorphy,” in which individuals are literally half female and half male. (XY can also do this, but very rarely.) Also, what if, like crocodilians (read: other archosaurs) dinosaurs had temperature-determined sex determination? I realize Crichton was using the frogs for freak’s sake, but the poor frog seems to be the scapegoat for everything that goes wrong in that world. Give other animals a chance.
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