When you want to find high biodiversity, the first idea that crosses your mind would probably be to go to a tropical rainforest. Do not bother! Just take some mud from the nearest pond or lake! Each gram hosts billions of organisms. Microbes form the vast majority of life on Earth and they also make up for most of the biomass. Why are they so often neglected?
Assessing Microbial Diversity – What Is the Problem?
Well, beyond the obvious fact that they are tiny, they are hard to study, and most people lack interest in such subjects, unless those microbes are somehow pathogenic and give them a more profound reason.
If you open a biology book, you will probably find only some few thousand bacterial species cited. How can that be?
The concept of species is quite clear for organisms having sexual reproduction. For those lacking such things and, furthermore, being able to exchange genetic material with other species, things get complicated. The threshold for two bacteria to belong to the same species has been progressively raised from around 90% to 97% DNA equivalence. But humans and chimps share 98% of their DNA.
How can you assess biodiversity without a clear definition on what a species is? Everyone knows E (scherichia) coli. We find it in our intestines, in freshwater, in a pond, up in the Andes or in the feces of a kangaroo, and it is supposed to be the same species. Does it not sound odd?
Microbes – What Is Their Habitat?
The whole planet and beyond: no matter how weird and hostile an environment is, it certainly hosts some microbes. Here are some examples:
- Deepwater thermal vents – extreme temperatures and pressure, no oxygen – many bacteria love this.
- Hellish depths – bacteria were found kilometers below ground; actually there is quite a varied biodiversity in there.
- Up in the air – dozens of kilometers above ground, spores are to be found.
- Petroleum deposits – some microbes just love petroleum and oil products; so much that they sometimes live in the water above such deposits.
- Ice, snow, glaciers (above, inside and beneath), permafrost.
- The final frontier – it is unclear whether they live on other planets, but we surely take them when we travel to space.
What Does It Mean?
Microbial diversity comprises various kinds of organisms:
- Bacteria – a simple word, but differences between various groups are huge.
- Various protists.
- And, maybe, the elusive nanobacteria and nanobes.
Small, but many, extremely important to the whole biosphere, microbes constitute the bulk of the biodiversity on our planet.