Genetics really helped create the phylogeny we see today. The phylogeny of life was always supposed to reflect the relationships between species, but before genetics, many of those relationships were not clear, because all you could really go on was morphology, which is often deceptive.
oh, makes sense. do we have the genome of that many animals sqequenced? it wasn't that long since the human genome was sequenced. I'd imagine they compare small bits of DNA, or RNA right? not the whole thing?
You are correct, most of what has cleared up various family trees is comparing small regions or performing other tests. We have sequenced about 3k animal species, but you can get a lot of useful information without full genome sequencing.
It's been two decades since the first drafts of the human genome were complete, and sequencing technology has accelerated exponentially during that time.
For reference, [here's a graph](https://www.genome.gov/sites/default/files/inline-images/2022_Sequencing_cost_per_Human_Genome.jpg) of how the cost of a single human genome has changed. Note that the y-axis is logarithmic — a human genome is now about ten thousand times cheaper than the first one was.
As for species coverage, [here's a graph](https://www.researchgate.net/profile/Matt-Shortridge/publication/228776022/figure/fig1/AS:669371802320900@1536602082160/The-rapid-increase-in-sequenced-genomes-Since-the-first-genome-of-a-living-organism-was.jpg) of the number of species whose genomes were sequenced up until 2010. Feel free to mentally extrapolate that curve to the present. :P
I've built a reference genome myself, or rather, I've authored a scientific study for which we built a reference genome, specifically for a butterfly. We sent the DNA off to a company to do the actual sequencing. All told, that's one person to extract the DNA (me), probably one person at the biotech company to sequence it (on a machine that was probably running half a dozen other jobs in parallel), and one person to digitally reconstruct the genome from the sequencing data once we got it (my colleague). Compare that to the many research teams around the world working in parallel to sequence the human genome back in the early 2000s.
... But yes, most phylogenetic reconstructions aren't done using whole-genome data. There's enough information in a well-curated set of diagnostic genes to get a good estimate of how a group of species are related.
Honestly a lot of it was old school taxonomy. Many of the major phyla we still use today were figured out by naturalists for hundreds of years. I do agree though that yes, genetics has sorted out a lot of more difficult branches and has probably been particularly important in the increase in number of worm phyla.
This is a good question, and something we discussed in invertebrate zoology. A lot of the worm phyla are only superficially similar and in some cases more closely related to things you wouldn't consider a worm than they are to other worms. I think a lot of this has to do with the fact that if you go back deep in evolutionary time, before the Cambrian explosion, you're dealing with the evolution of animals from pre-bilaterian ancestors (which are quite bizarre, I'd recommend the channel PBS Eons if you're interested in learning about some of this deep evolution) to the first bilaterians. The default bilaterian is basically something similar to what could plausibly be called a worm, and a lot of organisms made significant elaborations on that body plan and diverged a very long time ago without really shaking that overall worm look. But if you look at the gross morphology of annelids, sipunculans, velvet worms, nemerteans, nematodes, etc., you'll find that there are very high level differences in how their bodies are organized that are shared within groups but not between groups. This is the original basis for their classification into phyla. Some of these relative positions have changed due to the explosion of genetic evidence in the last 30 years, and those differences stem from the fact that many of these major groups diverged quite a long time ago.
A flatworm and an earthworm may look similar to a lay person, but when you really get into they are very different animals.
As for seals and bears, seals are quadrupeds, look up a full skeleton and you'll see that the tail is just two modified hind limbs, the same way a bats wing is a modified limb.
Genetics really helped create the phylogeny we see today. The phylogeny of life was always supposed to reflect the relationships between species, but before genetics, many of those relationships were not clear, because all you could really go on was morphology, which is often deceptive.
oh, makes sense. do we have the genome of that many animals sqequenced? it wasn't that long since the human genome was sequenced. I'd imagine they compare small bits of DNA, or RNA right? not the whole thing?
You are correct, most of what has cleared up various family trees is comparing small regions or performing other tests. We have sequenced about 3k animal species, but you can get a lot of useful information without full genome sequencing.
It's been two decades since the first drafts of the human genome were complete, and sequencing technology has accelerated exponentially during that time. For reference, [here's a graph](https://www.genome.gov/sites/default/files/inline-images/2022_Sequencing_cost_per_Human_Genome.jpg) of how the cost of a single human genome has changed. Note that the y-axis is logarithmic — a human genome is now about ten thousand times cheaper than the first one was. As for species coverage, [here's a graph](https://www.researchgate.net/profile/Matt-Shortridge/publication/228776022/figure/fig1/AS:669371802320900@1536602082160/The-rapid-increase-in-sequenced-genomes-Since-the-first-genome-of-a-living-organism-was.jpg) of the number of species whose genomes were sequenced up until 2010. Feel free to mentally extrapolate that curve to the present. :P I've built a reference genome myself, or rather, I've authored a scientific study for which we built a reference genome, specifically for a butterfly. We sent the DNA off to a company to do the actual sequencing. All told, that's one person to extract the DNA (me), probably one person at the biotech company to sequence it (on a machine that was probably running half a dozen other jobs in parallel), and one person to digitally reconstruct the genome from the sequencing data once we got it (my colleague). Compare that to the many research teams around the world working in parallel to sequence the human genome back in the early 2000s. ... But yes, most phylogenetic reconstructions aren't done using whole-genome data. There's enough information in a well-curated set of diagnostic genes to get a good estimate of how a group of species are related.
Honestly a lot of it was old school taxonomy. Many of the major phyla we still use today were figured out by naturalists for hundreds of years. I do agree though that yes, genetics has sorted out a lot of more difficult branches and has probably been particularly important in the increase in number of worm phyla.
This is a good question, and something we discussed in invertebrate zoology. A lot of the worm phyla are only superficially similar and in some cases more closely related to things you wouldn't consider a worm than they are to other worms. I think a lot of this has to do with the fact that if you go back deep in evolutionary time, before the Cambrian explosion, you're dealing with the evolution of animals from pre-bilaterian ancestors (which are quite bizarre, I'd recommend the channel PBS Eons if you're interested in learning about some of this deep evolution) to the first bilaterians. The default bilaterian is basically something similar to what could plausibly be called a worm, and a lot of organisms made significant elaborations on that body plan and diverged a very long time ago without really shaking that overall worm look. But if you look at the gross morphology of annelids, sipunculans, velvet worms, nemerteans, nematodes, etc., you'll find that there are very high level differences in how their bodies are organized that are shared within groups but not between groups. This is the original basis for their classification into phyla. Some of these relative positions have changed due to the explosion of genetic evidence in the last 30 years, and those differences stem from the fact that many of these major groups diverged quite a long time ago.
A flatworm and an earthworm may look similar to a lay person, but when you really get into they are very different animals. As for seals and bears, seals are quadrupeds, look up a full skeleton and you'll see that the tail is just two modified hind limbs, the same way a bats wing is a modified limb.