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The Earth. Home to an amazing biodiversity, from towering elephants to the tiniest microbes,
from lush rainforests to apparently barren deserts.
This biodiversity has always fascinated humans, who have tried to describe and classify this
amazing display of life. You have probably heard before that “there is still a lot
to discover” but… to what extent? Do we really know with whom we’re sharing the planet?
A few years ago we thought we knew, but in recent years our ability to access and analyse
molecular data has revealed an unexpected bias in our knowledge.
Especially, in eukaryotes, the domain of life that includes all organisms with nucleated
cells, like human’s. Let me illustrate this bias.
Imagine the whole diversity of eukaryotes as an island. According to the traditional
catalogue of species, 97% of all eukaryotes are either animals, plants or fungi.
Given they are mostly multicellular and visible to the naked eye, the commonly called “visible
biosphere” is here represented as the surface of the island.
The arrival of microscopes unveiled the world of the unicellular, here represented as the
submerged part of the island.
According to the traditional catalogue, unicellular eukaryotes, called protists, represent only
a 3% of its whole diversity.
Until very recently, this picture was thought to represent eukaryotes, and everything we
know about them comes from it.
And it indeed represents eukaryotes as we literally see them, but not as they really are.
The real picture started to build up when we acquired the ability to identify organisms
through their genetic data.
This fact revealed an unforeseen diversity in protists, challenging all predictions and
radically changing the image we had of eukaryotes.
First, we see that most of the eukaryote island is actually underwater, implying most eukaryotes
are unicellular. The initially thought-to-be minority is, in fact, an absolute majority.
Second, everything we know about eukaryotes represents a very small sample of their diversity.
This means we are biased, as we know a lot, but about very little.
On the one hand, these conclusions raise questions like: can we say we know what a eukaryote
is, when most species have never been described?
On the other hand, this unknown diversity may be hiding potential discoveries and applications
that could forever change our society.
Fortunately, molecular data, which evidenced the bias in the first place, is at the same
time one of the keys to revealing the true diversity of eukaryotes.
This is why the Multicellgenome Lab is one of the labs that are analysing molecular
data to find new protists.
Because it will not only change our perception of eukaryotes, but it will also change our
perception of the world.