German wikipedia defines a biological species as a group where individuals can reproduce offspring with other members of the group, but not with individuals outside of the group.
First of all, to the best of my knowledge, proper sexual reproduction only happens with Eukaryotes. Then this means that no bacteria ever reproduce offspring with other individuals, and therefore each bacterium is its own species.
But that is a meaningless definition. If each bacterium is its own species, then the categorization into species becomes meaningless.
On top of that, bacteria have “pseudosexual” horizontal gene transfer (HGT) which allows them to exchange genetic material with any other bacterium (if the circumstances are right; if i understand this correctly). So all bacteria are in a single species if you look at it that way.
I understand that bacteria normally don’t undergo HGT with all other bacteria because some might only open up at hot temperatures while others only open up in cold temperatures - thus creating a natural barrier. But it is also my understanding that while such barriers exist, they’re not permanent and can be overcome in nature (without human intervention) for example due to certain virus infections and similar circumstances.
Long story short:
Wouldn’t it make more sense to just consider that the concept of “species” only apples to eukaryotes and not to bacteria at all? Wouldn’t that save all of us a headache? Maybe we should consider bacterial species to be less strict that eukaryotic species. Maybe we should describe bacteria by their individual features and give that group a name, instead of expecting that diverging lines of evolution cannot ever come together again.
It’s based on phylogeny trees. Just search up the phylogeny tree of bacteria and you will know what I’m talking about it’s DNA relationships.
Edit: two species would be different because their 16S or 23S rRNA is different.
If I had to offer my own definition, I’d say populations belong to the same species if they evolve a similar range of responses to all selection pressures (assuming they can’t otherwise be distinguished by morphology etc).
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Fortunately, the charging one has been solved now that we’ve all standardized on mini-USB. Or is it micro-USB?
There’s a key difference, though: standards just affect the way we and our devices interact with each other, but taxonomy affects the way we interpret the natural world. There’ll always be an arbitrary element to it, but we can try to make distinctions that best correspond to objectively useful differences (to “carve nature at the joints”, as Plato put it).
“Maybe we should describe bacteria by their individual features and give that group a name”
We already do that. The function and genes of bacteria are what defines a bacterial species (or genus, family, or order). I do agree that the Wikipedia definition of “species” doesn’t strictly apply to bacteria due to asexual reproduction and HGT. But it is still a useful tool for classifying bacteria.
Giving it a name makes talking about the organism easier. If I know that a person is infected with Staphylococcus aureus I know that the characteristics and treatment are going to be very different than if they were infected with Pseudomonas aeruginosa. Giving it a species name is a lot easier than saying they are infected with a coagulase positive, gram positive coccus.
function and genes of bacteria
I think i might have to write down that phrase somewhere, as it seems an interesting phrase.
thanks for the well-balanced answer anyways :D
The podcast Let’s Learn Everything did an episode on this- the answer is that most fields of study under biology have different definitions based on their needs - there’s about 20 or so definitions in use currently.
