May
18th
2016
It's Evolution, Baby · 7:28pm May 18th, 2016
If someone was to tell you that the following five creatures evolved from a common ancestor, and that each new trait evolved only once:
Could you determine their phylogenetic tree based on their physical characteristics? What order did the traits evolve in?
Definitely not asking because there might be a biology test question for high school students based on this in order for them to demonstrate their understanding of evolution.
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Titanium Dragon · 1,024 views
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#evolution
#pony evolution
#god I am a nerd
#biology
#biology test
Lauren Faust came first!
3954245
Hm. I suppose I could throw in an alicorn, too...
Hmm...
Okay, looking at it cladistically, definitely group the winged ponies together, and I suppose the earth pony and zebra. The different body structures and cutie marks suggest that all but the donkey share a common ancestor, and based on what I know about mutual reproductive capabilities, the zebra likely differentiated from the ponies prior to the development of wings.
So, if you'll pardon the attempt to describe a phylogenetic tree through words rather than, say, clumsy ASCII art, the donkey would branch off first, followed by the zebra, then the earth pony, and finally the pegasus and bat pony/thestral/chiropteron/what-have-you.
... Wait, we aren't counting the hat or jewelry as biological traits, are we?
Given that Earth Ponies can produce a Pegasus, they're technically still variants of the same species, which means the extra-limbs bit is, somehow, less of an issue in Equestria than on Earth.
It would otherwise make sense that the Pegasus and the Batpony were most recently linked, due to the extra limbs, but here it may be a case of convergent evolution.
Donkeys and Zebras are about equally far from ponies IRL, with both being capable of non-fertile mixed offspring (Mules and Zebrids), but Cranky looks less like Applejack than Zecora does.
3954255
No. But that's a good point; I should find ponies without those.
3954257 That video fucked me up when I stumbled upon it during my angsty failing-college-and-pondering-life year.
I'll say! What's this talk of "evolution"? Next you're going to say that Equus orbits the sun!
Harumph.
Hmm, well physical traits aren't the best thing to judge phylogenetic trees off of, but by loose parsinomy:
LUCA --- (side branch to winged equines, subdivides into pegasi and thestrals) --- hoofed equines branch --- (side branch to donkeys) --- split to earth ponies and zebras.
Justification:
Zebra and earth ponies have the least physical differences (coat colour alone really) so these are the last seperation.
Donkeys have some minor differences in leg bones but lack wings, so have seperated before zebra and earth ponies but after the winged equines.
Winged equines seperate via common ancestor then split into two species as double evolution of wings is posible but not likely without additional evidence
3954259 I'd say Thestral and Donkey split off first. While they kept growing, the others shrinked.
Then, they both split off into Thestral and Donkey.
Afterwards, the pegasi split off from the smaller tree.
That leaves the earth-pony and zebra. The Zebra developed bones more pointy than the earth-pony, and stripes.
Just noticed missing Unicorns
s32.postimg.org/px1v3nphh/Untitled.png
Do you have a pony related question in your bio class test...?
3954302
The question is whether or not high school students will :V
The goal behind the question is basically to see if they understand some of the basic principles of evolution, and whether or not they can create a phylogenetic tree for organisms they're unfamiliar with. I'm using made-up creatures because A) real creatures generally aren't so easy to do this with (they're far too variable, and their traits tend not to be as obvious) and B) I want to test whether or not they understand the principles of evolution and phylogenetic trees; using real-world creatures just tests whether or not they happen to be familiar with the particular evolution of a specific branch of organisms.
However, I don't want this to be too observation-based; I don't want to be too sneaky about it. I want the traits to be obvious. I was concerned that some of the traits I was aiming for people to notice may be too subtle, and if pony fans can't see them, I'd be concerned that someone totally naive to them wouldn't see them, either. Everyone is noticing some traits (wings), some people are missing some traits, and no one has mentioned one of the traits I was hoping people would notice, so I may end up going with outlines rather than actual images, so as to highlight the traits in question. Sadly, I'd lose one trait that way, but I could make use of another trait instead anyway.
Also, may end up subbing in an alicorn for the bat pony; not sure yet.
Anyway, to folks who are still guessing: more guesses are appreciated.
Also, there isn't necessarily one right answer; the goal is to demonstrate understanding, not get exactly the tree I constructed. As long as their tree is consistent with the evidence provided, it doesn't really matter (as the test is hand-graded).
Under the stated assumption "each new trait evolved only once", this is how I'd form the tree:
Common Ancestor
/ \
<Donkey> Fluffy Tails/flat legs
/ \
Nose nub <Zebra>
/ \
Wings <Earth Pony>
/ \
<Pegasus> <Bat pony>
However, IMO it's far more likely that the nose evolved twice, as otherwise the Zebra and Earth pony are almost identical, and wings are a massive change that happens over a very large amount of time.
Going from that, I would make the following tree
Common Ancestor
/ \
<Donkey> Fluffy Tails/flat legs
/ \
Wings No Wings
/ \ / \
<Pegasus><Bat pony> <Earth Pony><Zebra>
It could even be argued that wings are such a massive difference that the Donkey split should happen after the Wing/No Wing split. To account for the similarities between the others, the common ancestor would start with a lot of the features and then differentiate further. Note that while I have the final species as midpoints, that's more to indicate that the common ancestor would be very similar to that final species and not that the ancestor actually was that species.
<Earth Pony>
/ \
<Zebra> <Pegasus>
| |
<Donkey><Bat pony>
The thing thats really throwing me is the wings. Gaining extra limbs would have to have happened far in past, making the otherwise similar forms an example of convergent evolution. Of course since they can interbreed (i think) that throws that idea out.
Obviously a case of intelligent design...
3954315 Guesses for subtle traits:
Zebra tail, much longer dock
Thestral, Cat eyes, fangs and ear tuffs
Non-donkey, cutie marks
3954330
derpicdn.net/img/view/2013/11/1/461703__safe_shipping_straight_scootaloo_sweetie+belle_apple+bloom_big+macintosh_cheerilee_hearts+and+hooves+day_cheerimac.jpeg
Well before trying to order them I think its best to start noting the differences. Because It shares the most aspects with each of the others I am going to be noting the differences in relation to the earth pony. (I am discounting coloration as a single picture would not tell us the range of colors in a species. I am also discounting hairstyle as it might be a matter of personal choice)
The donkey has several key differences. Judging by knees, hooves and facial shape (more elongated) it seems to posses a significantly different bone structure. Other differences include ear shape (long and drooping) and tail with far less hair. As the eyes are closed we can not determine anything about them.
The zebra's differences are less obvious, but somewhat related. Like the donkey, the zebra's facial structure seems slightly elongated compared to the rest though not to the same degree. The zebra also possess a tail with less hair than the rest of the ponies, though again not to the same degree as the donkey. The zebra also uniquely possesses slanted eyes. (edit: also appear to be missing eyelashes)
The bat ponies possess leather? wings, slightly different ears and slitted iris's.
The only visible differences possessed by the pegasus are the presence of feathered wings.
While in the real world flight would require specialized bone structures, due to the lack of information we can not actually say whether those bone structures are present in the flightless species.
I'm surprised that, in all these lists of traits, no one mentioned that the threstal is where we apparently see the introduction of hemi-palpebralism, colloquially known as "bedroom eyes", a signalling that expresses a desire to mate with homo iwtcird, aka the Equestrian clopper.
Honestly if something like this were on a test I think the only honest way to grade would be based on the answer being well thought out and logically sound, because there simply isn't remotely enough information provided. Bringing outside knowledge makes it worse as those who have seen the show know that the pegasi and earth ponies are confirmed to be members of the sames species.
Hmm.
So first there were pegasi: a sort of proto-species with a colour scheme so hideous that looking at them was like being maced in the eye sockets, until a branch-off became bat-ponies through the evolution of actual colour-coordination. This trait refined through the centuries and led eventually to the zebra; note the monochrome coat that goes with anything, the evolution of pattern to complement the colour, the loss of those dreadfully so-last-universal-ancestor wings, darling, and - most importantly - the transformation of the golden eyes into bitching golden bling.
This bling, in fact, was so bitching that it overrode the need for anything else. The stripes faded; the garishness returned; but this new branch had the clear advantage of the sweet hat and rose speedily to dominance. Evolving further over centuries, they shed bodily beauty and concentrated their hatware traits until the final pinacle:
donkeys in toupées.
Though, actually, I was listening to some David Attenborough recently, and apparently birds that come to occupy areas without predators almost universally lose the ability to fly over time, because flying is sub-optimal and very energy-intensive. So perhaps the pegasus is the first.
3954505 Oh, my. This means Scootaloo is the first in a new generation of flightless pegasi. We need to reintroduce griffons into Ponyville to encourage more predator behavior or the whole race could become groundbound. (snerk)
To determine the order that traits evolved, you would need to specify an outgroup so that you could root the tree.
The donkey's probably close to the base species, but split before Cutie marks made an appearance.
Zebras and earth ponies both have a number of similarities, but were divided by geographic regions.
The pegasi and bat ponies both evolved from earth pony stock, taking different approaches to flight.
Alicorn Ancestor
------------------------------------------
/ | \
Wings No Wings or Horn <Unicorn>
| / \
<Pegasus> <Earth Pony> <Zebra>
| |
<Bat pony> <Donkey>
Or more likely:
Alicorn Ancestor
------------------------------------------
/ | \
Wings No Wings or Horn <Unicorn>
| |
<Pegasus> <Earth Pony>
| / \
<Bat pony> <Donkey> <Zebra>
Probably not what you're looking for, but we are talking about Magic™ and Equestria...
3954588 Either that or pegasi will have to return to the old ways of 'fly or fall': throwing their kids off the edge of a cloud when they reach an age where they need to start foraging for themselves. It's politically better than Celestia declaring a new eugenics program.
If Scoots is clever enough, she'll be wearing a para-sail or a squirrel suit. I'm voting for 'chicken in a squirrel suit'.
3954879 You know, there's probably a story in there:
Leaving the Nest - There comes a time in every young pegasi's life when their parents give them a gentle nudge out the door so they can make a life of their own.
Then there's Rainbow Dash.
"Mom!" bellowed Rainbow Dash as she rummaged through the kitchen cabinets. "Did you get those alfalfa cheese puffs I asked for?"
"Sorry, Rain," called her mother back from the basement of their cloud home. "I guess with the second job I'm holding down and all of the extra cleaning that's involved with having our darling daughter stay with us after graduation, it just slipped my mind."
3955083 Yeah, that's where the whole 'napping 12 hours a day on a cloud' came from. Nurtured enabling.
You should totally write that, of course.
!
Ok, so evolution is not my 'thing'. I was raised as strict Christian who disbelieved all things science, only to start thinking otherwise in my late teens. But I'm going to take a stab at it. Read the previous comments, very interesting. But still kind of missing a few things.
Here's my list
Common ancestor (of whatever)
------------------------------------------------------
|
|
Donkey
| \
| \
| |
| |
| Zebra
| | \
| | \
| | |
| | Earth Ponies
| | | \
| | | \
| | | |
| | | Pegasi
| | | | \
| | | | \
| | | | |
| | | | Batpony
| | | | |
| | | | |
I suggest this set up because of a few things. If each change is done only once, right? Ok, so first you have Cranky/Donkeys. They are four legged equine who are sentient. The change comes with a change to their body (more solid limbs, shorter snout, longer fur on their tail and head, appearance of a mark on their sides). Then, from zebras comes another change to earth ponies. The marks appear with a special meaning and at special times (so far as we know canonically). The colors brightened, the body more solid than before, eyes and ears rounding out a little and more fur on their tails and heads while their hooves went from split to solid. Then comes Pegasi. Their bones hollow out (like birds?) to lighten their loads while wings grew to help with where they are located (probably mountains). Lastly comes the batponies. They would be the pegasi who adapted for night time. Their eyes changed to absorb more moonlight like a cat's, their wings stronger and able to help hold them aloft without the winds that would normally appear in the daytime.
... And that's what I think. Not exactly sure, but meh, gave it a shot.
My attempt (assuming donkey is the outgroup):
i1082.photobucket.com/albums/j366/structural_biologist/mlp_phylogeny_zpsh8gbvpe8.png
Feathers, stripes, cat eyes, ear fluff, wings, and a rounded snout are all clearly derived characteristics. It's unclear whether droopy ears and a thin tail are ancestral or derived. Cutie marks are likely derived (because no other species likely have them).
Now the real question: How would griffins fit into such a phylogeny? Independent evolution of wings and feathers? Or perhaps there's more horizontal gene transfer in Equestria than on Earth.
3955406
A+ full credit.
Ooh, fun! Wish I'd had questions like this more often in school.
Let's see... assuming I weren't aware of magic/the ponies' interesting subspecies setup, I'd probably go with something like this:
(Note: 1 = donkey, 2 = pegasus, 3 = bat pony, 4 = zebra, 5 = earth pony)
The common ancestor was all-but-certainly winged, since adding functional new limbs is so much more difficult than losing them that it may as well be impossible given the "each trait only developed once" constraint; in the time it took to develop wings, the winged/wingless lines would be practically guaranteed to diverge too much to match their visually-similar depictions here. Note that since this would imply a six-limbed initial body plan, 1/4/5 would be distinct from any wingless ancestors that may have preceded the (winged) most recent common ancestor. (Obviously this conflicts somewhat with the representation in the show, but since I'm trying to work the no-prior-knowledge angle here...)
In body structure, 3-2-5-4-1 form a relative continuum.
Assuming the hip symbols are part of their biology rather than decorative (you'll really want to clarify that if you use this as a question!), 1 is unique for lacking one entirely and 4's is quite distinct compared to 2/3/5s'.
4 is unique in having body patterning and foot patterning.
2 and 4 are the only ones which have longhairs with significant patterning, with 3 having somewhat less. However, given the variability of coloration shown, the most likely-seeming explanation is that patterning is present but not ubiquitous in 5 and possibly 1, with the individual(s) shown simply not possessing it.
Preliminary conclusion: 2 is likely the most representative of the common ancestor, with 3 being either a descendant of 2 or a close cousin, but it could be the other way around. The winged/wingless split could theoretically have resulted in the depicted wingless species in multiple ways, but the constraint that each trait developed only once suggests that 5 diverged from 2 directly into the form shown. The ancestor of 1/4 would have then diverged from 5 and developed 4's body plan (and possibly symbol) before splitting, with 4 retaining the same body plan but developing its unique patterning/symbol while 1 retained the original patterning but continued developing its body plan and lost its symbol.
Obviously, depending on how you define "only developed once", a lot more possibilities could open up. One could make a case for letting it include things like reverting to a lost ancestral trait, hybridization, and/or having a trait develop simultaneously in already-diverged species, with the expected complicating results.
Going to pass on the trait-ordering for the moment, since I'm not clear on how specific you're looking for. Stuff like wings/tails/slit eyes is obvious, but there's a bunch of smaller stuff people might pick up on too: tuftiness, longer ears, muzzle shapes, eye shapes, eyebrows/lashes, body shapes, differences in how Cranky's/Zecora's legs are drawn vs the ponies', etc.
3955528
Your thought about wings as complex structures which would be hard to evolve (and thus, were probably lost) is an interesting one.
Thanks for spending so much thought on this. I was kind of concerned that people would have multiple ideas about how it would go... and they have :V But you came up with a very reasonable explanation for your tree, which works very well. Well done.
3955406 I agree with your assessment and it makes for a falsifieable hypothesis, insofar as the presented species are concerned (There should be a common ancestor that is extinct, but should be present in the fossil record).
As to how Griffons fit in there? The same way that Birds and Bats fit, I suppose. There must have been a virus that transfered genetic material from one species to another. Highly localized, high rate of infection, especially cross-species. Adding a range of (sometimes or mostly) non-lethal effects (so it becomes quasi-symbiotic), including a faulty dna/rna copying mechanism resulted in a short term high-speed genetic transfer between species. Due to the high rate of genetic manipulation in the virus itself (due to the constant transfer of genetic material in and out) it died out due to an incapability to reproduce. Of course, this should be evident, when comparing the transfered genetic material by running dna mappings of the concerned species.
Either that, or magic...
3955564
IRL, flight has actually evolved independently a bunch of times. Birds, bats, pterodactyls, and insects all independently evolved full flight without lateral gene transfer. On top of that, there are numerous other species which have evolved gliding, ballooning, or, in the case of flying squid, jet propulsion.
Hard to really say how a lot of the critters in the MLP-verse evolved; pegasi have both feathers -and- fur. Are griffons birds that look like mammals, or mammals that look like birds?
3955591 Yes, however not a lot of those methods developed several times independantly. Since we found out how feathers evolved, it would be less likely for mammals to produce them from scratch. Considering their complexity it would be even less likely to get them from two different sources to begin with. So, it actually turns out that 3955528 might have had the right idea with the loss of limbs, if you want to consider that perspective.
Also, horizontal gene transfer is much more common than you might think (especially in single-celled organisms), although my interpretation of it is of course... fantastic (literally).
3955591
3955600
Many complex traits have evolved many times independently--for example, multicellularity has evolved independently at least 40 times on Earth. Similarly, as TD correctly points out, flight has also evolved independently multiple times. However, in each of these cases, the wing structures are very different. In the case of the pegasus wings, however, they are clearly very similar in structure to bird wings despite the fact that birds are less related to horses than other flighted mammals (like bats). Independent evolution of such complex structures as feathers is less plausible. In fact, because birds are closely related to reptiles, evolutionary it would make more sense for dragons to have feathered wings and pegasi to have leathery, bat-like wings.
Clearly, the conclusion we have to draw is that pegasi are genetically modified.
I don't know, but something about Cranky's mane makes me feel like he's presidential material.