Hey guys Julia here for DNews
The tree of life is HUGE.
HUGE.
According to a draft described in the journal Proceedings of the National Academy of Sciences.
The latest draft of the great tree named over 2.3 million species of animals, plants, fungi,
and bacteria.
Previous versions of the tree of life only charted about 100,000 species.
But this new HUGE tree is truly an awesome sight to behold.
To get a close up look at the whole thing check out https://tree.opentreeoflife.org.
There’s a link in the description.
But that got me wondering, with millions and millions of species on this planet.
How do we tell them apart?
Evolution is a beautiful thing.
The branches of life spread out in every direction as life finds a way into every niche imaginable.
A new species arises in a process called speciation.
It’s when something happens to separate it from all that came before, like a new trait
or geological isolation.
Naturalists like Charles Darwin used to tell species apart the old fashioned way.
Just by lookin’ at em, which is called morphology.
It’s telling species apart by their appearance.
But there’s another way to define a species, biologically.
I’ve often heard a species defined as animals that can reproduce and make a viable, fertile
offspring.
Basically if two animals can make a baby that lives and can later make it’s own baby,
then those two animals are the same species.
Which is basically what the Biological Species Concept (BSC) says.
This concept was introduced by biologist Ernst Mayr in the mid-20th century as "species are
groups of interbreeding natural populations that are reproductively isolated from other
such groups."
But both of these definitions aren’t perfect.
Life finds a way.
So sometimes creatures that look wildly different can breed.
Like take dog breeds for example.
If you were an alien taxonomist coming to Earth for the first time, you might be very
confused by how all these creatures, from the smallest to chihuahua to the greatest
Dane could possibly be the same breed.
On the other hand a group of animals that look an awful lot alike can actually be different
species.
In some cases different species evolved similar traits because they’re in similar environments
like Fossas and cats, which cannot reproduce.
Or different species might be closely related and look a lot alike but can’t produce fertile
offspring.
Like horses and donkeys.
Sure they can produce a hybrid called a mule, but they’re sterile.
But even on a finer level, sometimes scientists get a surprise and find that different species
might not be so different after all.
And that’s just the trouble a group of scientists in Australia ran into.
In a study published in the journal Biology Letters researchers found that different species
of Rock-Wallabys were swapping DNA!
Six different species of rockwallaby were thought to be separate species because the
way their genetic material package would stop an offspring from being fertile.
But upon genetic analysis the researchers found gene flow between the species, suggesting
something else was going on, forcing them to rethink their evolution.
This finding suggests that these animals were getting it on, making babies that could make
some more babies.
The rock-wallabies might not be “reproductively isolated”, possibly meaning they were more
like a single species than previously thought.
Like in the case of these rock-wallabies scientists could see a species’ history written in
its DNA.
Thanks to modern technology, molecular genetic sequencing changed the game in biology.
By comparing the DNA of different animals, scientists can see how they’re related or
not.
This was a huge advance in the field of taxonomy.
It’s how we know our closest cousins are chimps and bonobos, if we went by morphology
alone, perhaps we’d think orangutans were our next of kin.
According to a study published in the Journal of Biogeography we share more physical features
with orangutans, like beards on men and similar shoulder blades.
But molecular genetics revealed we share only 97% of our DNA with them and 99% with chimps
and bonobos.
So it can help us not just learn about the rest of world, but taxonomy helps us find
our place in the animal kingdom too.
Some people think taxonomy and naming species is dumb, because it does seem somewhat arbitrary.
I mean humans are the ones deciding where those lines between species are.
But I think it’s really important.
Because humans need to categorize things to make sense of this crazy, chaotic world.
and it’s so important to keep track of all the diversity of life on this planet, while
it’s still here.
There’s a real risk we’re losing species before we can even find them.
So no, taxonomy isn’t perfect.
But it’s the best we’ve got.
Taxonomy helps us know our history, like when recently scientists announced the discovery
of yet another human-like ancestor.
So Julian asked the question, how do we determine if they belong to the genus homo in this great
episode right here.
Alright friends, if you haven’t heard the news yet, WE’RE DOING A LIVE SHOW.
RIGHT HERE IN SAN FRANCISCO!
I’M SO EXCITED!
We’ve got a great line up of all your favorite hosts.
I’ll be there, trace will be there Julian, Amy and Crystal will be there and so so many
more special guests like Dr. Joe Hanson from It’s Okay to Be Smart and Brian Brushwood,
magician, TV personality, host of Scam School, Anthropologist Natalia Reagan, and Dr. Carin
Bondar, Discovery Channel host and TED presenter.
It’s all going down October 22.
So grab your tickets before they’re gone.
there’s a link in the description.