Everyone keeps saying its like a list, how does that work?? Do you have like a pokedex where the undiscovered species appear in grey or something like that???
In: Biology
A part of it is that nowadays we are able to determine the existence of some species using what we call shotgun DNA sequencing. We basically take a bunch of seawater and just look to see what dna is in it. Almost always we find a bunch of dna that we cannot identify, except to say that it belongs to something we have not found yet.
But in other cases it is just making rough educated guesses based on how likely it is that there are more species out there.
If you find yourself in a new place on earth it’s likely that that biome exists some where else. If that biome is studied relentlessly and it is known that it has 20 species in it then its a pretty safe bet that the new place has 20 odd too.
You can also infer the existence of species from other species.
Imagine you find a forest and a fox. Now you know foxes don’t eat trees so that implies the existence of another animal that does eat trees and that’s what the fox eats.
Now if you find a forest and a rabbit then that implies a creature that eats the rabbits otherwise the rabbit population would grow unchecked and there would be no trees.
Go out and look for animals or plants or whatever
Find 100 different types
90 types were previously unknown
Go out and look for animals or plants or whatever
Find 100 different types
90 types were previously unknown
Go out and look for animals or plants or whatever
Find 100 different types
90 types were previously unknown
Go out and…
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Matt Parker did a video about this not too long ago, but when you’re studying a new region you can use mathematical tools to help predict how many species are still undiscovered in that region. The idea is pretty simple. You go out on the first day and likely most of the animals you find will be new species. You go out the next day and you’ll still find new species, but you’ll also see animals that you discovered previously.
If you repeat this enough times the ratio of new species to previously known species will steadily decrease. You can plot that decline on a graph and use that to figure out how many total species are in that area.
Well, one thing I haven’t seen anyone mention is that we have tools such as sound to look at an ecosystem as a whole. We can judge a general picture of health and activity.
Let’s say you listen to the Amazon rainforest. You might not know every insect and bird and animal sound but you could probably get an estimate of biodiversity. The same goes for other tools such as decomposition rates or studying a small area
Biologists have a trick for figuring out how many of something exist without counting them.
Let’s suppose you want to know how many butterflies there are in a forest. You could capture them all and count them, but that would be very difficult, and it would probably be bad for the butterflies, for the things that eat the butterflies, for the things the butterflies pollinate, etc, etc.
What you do instead is you get yourself a little paintbrush and some paint, and you start catching butterflies. Each time you catch one, you do one of two things :
1. If the butterfly is unmarked, you paint a tiny dot on it, release it, and write a “X” in your notebook. This a new butterfly.
2. If the butterfly is marked, you release it, and write a “O” in your notebook. This is a butterfly you’ve seen before.
When you start, every butterfly will be a new butterfly. If you continue, eventually you will see more and more butterflies that you’ve already seen. If every butterfly you see is marked, then you know you’ve caught every butterfly. But it isn’t necessary to go that far. In fact, you can probably stop after you’ve marked just a handful of O’s.
Next, you get a big piece graph paper and you make a plot. For each mark in your notebook, you move one space to the right. Each time the mark is an X, you move one space up. So, the horizontal is the total number of butterflies you caught, and the vertical is the cumulative number of new butterflies. It will start out looking like a straight diagonal line, but will gradually start bending into a horizontal line. The curve will be a little bit noisy, but you know that two things about it that must be true :
1. The curve must stay below a ceiling equal to the size of the population
2. The size of the population is the only parameter that affects the shape of the curve
So, as soon as you can see the curvature of the line, you know what the size of the population is. It doesn’t actually matter how slight the curve is — you only have enough observations to measure it.
This is called a [Mark and Recapture](https://en.wikipedia.org/wiki/Mark_and_recapture) experiment. There is a related approach for counting species called the [Collector’s Curve](https://en.wikipedia.org/wiki/Species_discovery_curve).
There are a few ways!
One way that we know that there are many undiscovered species in many taxa is to basically plot the cumulative number of species known over time. If the number is still increasing rapidly, there’s probably still *way* more out there. And there are some types of creature we’ve probably discovered all of- for instance, it’s been a long time since we’ve discovered a new species as large as an elephant (or even as large as a bison); it’s unlikely that we’ve managed to miss any. But there are tons of mites that live in soil, and wherever we look there’s likely to be new ones!
To get an estimate of *how many* more are out there, we can make estimates! A lot of the undocumented diversity is in places like rainforests. Scientists can go to a rainforest and VERY intensively document *everything* in a small area (for instance, tenting and fogging a single tree, or every single plant in a 100x100m plot), and determine what proportion of the organisms encountered were previously undocumented. Then, knowing how much more uninvestigated habitat there is, they can extrapolate how many other undocumented species there may be in that or similar ecosystems.
Sort of like, if you weren’t sure how many kids went to your kid’s school, you could count how many there were in your kid’s class, count how many teachers are listed, and multiply to get a reasonable estimate. It might be that kindergarten classes are smaller than 5th grade classes, and there will be class to class variation so you wouldn’t get an exact number with that method, but it would be pretty good.
first they can science the shjit out of it and basically say “given what we know, species containing [These DNA patterns] should definitely exist, we just havent found them yet” and other wierdness like that, but im pretty sure thats the minority.
most of it is extrapolation and educated guesses.
lets say you run a business selling balls for ballpits. You have like a billion balls spread out over a hundred warehouses, but its all the balls.
Some random guy decides he wants to buy all the balls that are red and ONLY red, because he is wierd like that.
You dont know how many of your balls are red, so you go to the first warehouse and count the first thousand balls. out of 1k, you have about 100 red balls.
You go to the second warehouse and count a batch of a thousand balls. You have around 100 red balls.
You go to the third warehouse and again have about a 100 out of a thousand.
you could go and count every single ball in every single warehouse, or you could extrapolate that you have about 10% red balls and go with that with a fiarly high degree of certainty, without needing to know EXACTLY how many red balls you have.
you have a billion balls, so you know you have about 100 million red balls, give or take a few million, even if you have never in your life seen more than a few hundred of them in your checks.
same thing with checking for animals, generally.
If every place you check has around 9 species you discover for every one you knew about, you can kind of assume most places you havent already checked are going to have around that much too on average, and from that you can further guess roughly how many species are around that we havent found yet.
Everything has been discovered, the only stuff that hasn’t are small variations. Like a kind of bird or snake that’s slightly different or a grasshopper pretty much the same as all the others. We know about everything.
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