Rumraket:
It has been known for quite a long time now that most animals, indeed the vast majority of multicellular eukaryotes have similar numbers of total protein coding genes, and that the majority of differences we see in their anatomical and physiological complexity owes significantly to mutational changes in gene regulation, as opposed to any straightforward direct relationship between protein coding genes and complexity.
Cc: @scd
This is borne out in a recent paper discussing the evolution of limb-like bones in zebrafish due to mutations in gene regulators. @sfmatheson has a thread on the findings:
This week there are a few really interesting papers in Cell that are about various key questions/themes in evolution. My favorite is about fins and limbs : the authors found a genetic “cassette” in fish genomes (zebrafish is their experimental system) that can be activated to induce the formation of bones that are normally associated with limb development. Two things jump out as especially interesting to me about the discovery:
The signaling system they describe was not previously known to be involved in limb development. The authors show that it is in fact part of limb development in mice. And it was discovered in fish! Wild.
The extra bones that develop in the activated mutants are strikingly normal; quoting the abstract, they “integrate into musculature, form joints, and articulate with neighboring elements.”
The graphical abstract is a nice way to explore what they found:
[fx1]
And here is the regular abstract:
Changes in appendage structure underlie key transitions in verteb…
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