This is a guest post by Rachel Rodman. Photos by Daniel Murphy.
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Every U.S. state has its own set of symbols: an official flower, an official tree, and an official bird. Collectively, these organisms form the stuff of trivia and are traditionally presented in the form of a list.
But, lists…well. As charming as lists can sometimes be, lists are rarely very satisfying.
the world’s smallest carnivore is called the “least weasel” i’m dying but like if it’s the smallest carnivore then it sure is the least amount of weasel you can have
Look at him: this is absolutely the least amount of weasel you can have
We evolved from something like this btw (before monkeys)
(lemurs and tree shrews, going backward, would be a better analogue, nothing similar to the stages before that survives but shrews and then some kind of possums would be the least worst, but still bad, analogies for what comes earlier)
Humans, monkeys, and tree shrews are both in Euarchonta, weasels are all the way down there in Carnivora.
Like, of course our proto-primate ancestor was “something like” a weasel in that both are mammals, but only in the same sense that it was “something like” a whale or a bat – everything is like everything else at some level of analysis. Weasels are specialized hunters of large (for them) preys, proto-primates were frugivore-insectivores and specialized tree-climbers; all they have in common are a generic “small mammal” look whi
… OK, OK, I’ll concede, I am being unreasonably pedantic. It’s pretty obvious you were talking about overall appearance. Well, I don’t tag these posts “pedantry” for nothing. If I’m being too annoying, I’ll bow out.
There should be a website where you input a list of species and it gives you the smallest clade that contains all of them
Like if you put in Homo sapiens and Bos taurus it says Mammalia, but if you put in Homo sapiens and Pica pica it says Vertebrates, and if you enter Felis catus and Cannabis sativa it says Eukaryota
You might be interested in the minutelabs Tree of Life explorer, which has just told me you are wrong and that Boroeutheria is smaller clade than Mammalia that includes both humans and cows, and Amniota is a smaller clade than Vertebrata that includes both humans and Eurasian magpies
Wonder what the most distant cousin of Homo sapiens that is still in Mammalia is
unsurprisingly, the platypus. monotremes are basal
Ok yeah I should have figured that
Huh, somehow I’d never seen that site before. Neat.
Huh, so it turns out that a couple years ago some guy used two of my infographics (one of which I use as my tumblr banner, from 9:16 on). Can’t see any credits around, though I might have missed them. A comment in which I linked at my DeviantArt page was presumably withheld for moderation (most comments are old; the author might not be looking at this video anymore). Still pretty neat, I guess?
Ok, I explain. So the major categories of vertebrates that we all learned as kids (fish, bird, mammal, reptile, and amphibian…) were first published around the 1750s by a man named Carl Linneas. He tried to classify all of life based on shared anatomical traits- things like fur, feathers, or scales, methods of reproduction, number of legs, and so forth. He created the system of Kingdom/Phylum/Class/Order/Family/Genus/Species, grouping increasingly similar organisms into groups that he put in these 7 levels.
Of course, Actual Nature is a continuum and does not care that one man tried to make all of it fit in seven equal boxes. And we’ve learned a lot since Linneas was working- dinosaurs weren’t scientifically described until decades after Linne’s death, and Darwin’s theory of evolution was published nearly a century later. Other technology, such as DNA sequencing, has only really become available in the past couple years (DNA hadn’t even been DISCOVERED yet in Linneas’ time.)
Enter phylogeny. While traditional taxonomy grouped living species based on anatomical traits, phylogeny groups species based on evolutionary relationships. As we’ve gotten a more complete fossil record, the old model has needed some updates.
Here’s a phylogenetic tree that I shamelessly grabbed from Encyclopedia Brittanica, showing relationships between major groups of vertebrates.
As different adaptations arose, some groups of organisms have changed very little over time, while others have continued to look quite different. Some of Linneas’ initial categories still hold up- Modern amphibians never developed the ability to lay eggs away from water, and resemble many of the early land-dwelling vertebrates. Likewise, all living mammals are more closely related to each other than to any other vertebrates, and therefore can occupy their own branch of the tree. “Fish” is an extremely messy term as far as phylogeny is concerned, but that may be the topic for another post.
As you can see, lizards and snakes are close relatives on a shared branch point. Crocodiles and birds, likewise, share the closest branch point to each other (Dinosaurs have been left off this figure, but are on the branch with crocodiles and birds). Turtles’ evolutionary branchpoint is a bit more debated, because their skulls have some features that are different than other reptiles, but let’s include them for now.
So, if turtles are reptiles everything from the turtle branchpoint onward is also a reptile. A valid phylogentic group is a common ancestor (branchpoint) and ALL of its descendents. Excluding birds, therefore, does not make a valid clade.
Linneas also didn’t know about dinosaurs, which have some traits more similar to other reptiles, but some types of dinosaurs gradually developed more bird-like traits. Modern birds are descended from a couple of small, feathery dinosaurs that survived the extinction. But, because those more transitional anatomical features are lost to the fossil record and not represented in modern species, it can be hard to get used to the idea that small, warm-blooded, beaked, feather-covered things are actually close relatives of scaly, cold-blooded things.
Hope this makes sense!
Wow you weren’t kidding
I think it’s also cladistically valid to say “all vertebrates are fish”.
Most (~95%) modern animals we would colloquially call a “fish” ( fins, scales, and gills) are a monophyletic clade of ray-finned fishes. But since we also refer to coelocanths, lungfish, and other lobe-finned fishes as “fish”, because they also have fins, scales, and gills, we have to include their direct descendants, tetrapods, too, for the same reason we have to include birds as reptiles.
If we include sharks and rays as fish, which many people do, we’re definitely not monophyletic any more- it’s two very diverged branches. Throw in hagfish, lampreys, lancelets, and a bunch of fossil species and now the term “fish” accounts for basically all vertebrates. (Are we counting sea squirts too? Then it’s all chordates!)
If we include EVERTHING that includes “fish” in its common name (starfish, jellyfish, crayfish)…. Forget about it.
MeetChristine Jewel Yabut, molecular biologist and phylogenist
1) What do you do?
My research focuses on the Phylogeny of an insect group (Trichoptera) that can be found in clean streams and rivers. I discover and describe new species from my group. The species that I discovered from the Philippines were collected in the streams of Los Banos, Laguna inside the University of the Philippines - Los Banos (Diplectrona lagunensis)and in Imugan, Nueva Vizcaya (Hydropsyche philippinensis). During my collection in Imugan, I also collected another new species that was described by a colleague who named the species after me. Cheumatopsyche christinae! I am now finishing a barcode library of the Insect species from the group Trichoptera in South Korea.
2) Where do you work?
I just finished my Ph.D. in Molecular Biology in Korea University last August.
3) Tell us about the photos!
[Left:]This picture was taken in South Carolina, USA when I attended a training for Aquatic Insect collection. I did a teaching assistantship during the period of the summer class.
[Right:]This picture was from Mindanao when I did insect collection from January 21-25, 2014. These amazing local people helped me during my sampling.
4) Tell us about your academic career path so far.
I graduated with a degree in B.S. Biology at the University of the Philippines Baguio. Then I entered Korea University for an integrated M.S. and Ph.D. program. I am now searching for a postdoc position and plan to describe many new species from the Philippines.
5) Anything else you’d like to share?
I am now finishing a barcode library of Korean Insects called caddisfly. This barcode library is like a tag of DNA consisting of 658 basepairs of DNA nucleotide sequences that can be referred to identify the name of the species.
