(no subject)

[trinityvixen]

Good article for those not up on their taxonomy.

I love disabusing human prejudice in the sciences. We're prone to giving so much attention to animals, and, within all of Animalia, mammals. The truth is that animals are so ridiculously outnumbered, species-wise, compared to bacteria. Hell, they can hardly compete in numbers with archaeobacteria.

I once saw this truly awesome graphic in a class where the phylums under the sub-domain Animalia were represented in size. There was a tiny kangaroo for the mammals and a beetle about thirty times the size of all the rest combined. One in five species of animal is a beetle, folks--not in terms of numbers of animals, but in terms of numbers of species. For every five animal species, one is a beetle. It just lets you know, then, how many out of five are insects. Now imagine how many orders of magnitude more bacteria species there are. Aiyah. Awesome.

Comments

[slackwench.livejournal.com]

That bacteria exhibit more genetic diversity than eukaryotes, and that protists exhibit more than animals is not at all surprising to me. Presumably all eukaryotes are descended from a single strain of bacteria, and it seems likely that all animals are descended from a single strain of protists (yeast maybe?). As I'm sure you know, when you isolate a population and let it grow independent of the rest of the universe, you get a lot of genetic drift (big changes in the group as a whole) but not a lot of variety between individuals. You can see that in humans, where we as a species have less genetic variation than a single tribe of chimps.

Re, beetles: what percent of the animal biomass are they?

[trinityvixen.livejournal.com]

Don't use the word "protist"--it's not a monophyletic clade :)

As for percentage of biomass, I don't have the stats at my fingers, and I can't call up the papers from home. But the insect biomass outweighs the rest of the animal kingdom by at least two-to-one.

[hslayer.livejournal.com]

Doesn't that go to show just how much MORE superior we are? We've crushed all potential competitors for our niche under our heel. Our big, multicellular heel. Yeeeees....

[trinityvixen.livejournal.com]

Right, which is why the average bacterium manages to either escape our attempts to kill it or manages to kill us. Don't fool yourself, man: it's the bacteria's planet, we just live here.

[hslayer.livejournal.com]

Ok, I was going to go on with my silliness, possibly working in the term "bioduhversity", but of course you're right.

At least until we ramp up the nanobots. I am so ready for those.

[hslayer.livejournal.com]

Of course, isn't the underlying reason for the much greater variation in bacteria versus plants or animals just the fact that they've been around so much longer? Both in terms of absolute time and to an even greater extent in terms of generations (due to their short reproductive cycle)? I dunno, seems kind of a mundane thing to be celebrating.

I'm also curious how the already-sometimes-nebulous concept of "species" gets applied to bacteria when it seems like they'd show even more gradual differentiation than larger species do, and DNA is more easily swapped between species. (I was blown away to learn recently that a "plasmid" is a real thing, having played Bioshock...and that it actually seems applicable to what they were in the game.)

[trinityvixen.livejournal.com]

Of course, isn't the underlying reason for the much greater variation in bacteria versus plants or animals just the fact that they've been around so much longer?

Some of it, yes. It definitely accounts for how there are more extinct species of bacteria than there have EVER been of animals. But there are other factors. You mentioned the ability to of plasmid (yes, they're real things, I use them all the time) DNA uptake. That, technically, would make a certain bacteria a "strain" not a "species" if the plasmid weren't integrated into the bacterial DNA (plasmids exist in the cytoplasm as separate, replicating strands). If it is integrated, you can make a better case for speciation.

Eukaryotes, on the other hand, are very difficult to mutate and change, and they have such specifically structured organelles and systems that it is very easy it destroy them if something is altered. The bacterium's lack of complexity saves it. Bacteria can live and even thrive with much of their DNA removed.