Mitochondrial genes are inherited maternally. They are not scrambled by recombination, and mitochondrial variation offers rough clues about evolutionary history. Insect people were using the back end of a mitochondrial gene known as CO1 to help identify specimens, marine invertebrate people liked the front end, and vertebrate zoologists used a different mitochondrial gene altogether. Hebert’s idea was that, out of a hodgepodge of related techniques, he could build a simple, universal identification system — assuming, that is, the same small piece of mitochondrial DNA worked reliably for all the animals in the world. “We believe that a CO1 database can be developed within 20 years for 5-10m animal species on the planet for $1b”

2020-12-18: Genomic Encyclopedia

Researchers announced a significant advance. They have assembled the largest catalog of microbes to date, containing over 50k genomes from 18k different microbial species—12k of which have never been documented before. Their study expands the known tree of life by 45%. They also found 700k viruses and linked them to their bacterial and archeal hosts, further illuminating the vast interconnections in this unseen world.

“It’s a fucking incredible amount of data. There are only ~10K species of microbes that have been cultured and described formally, and yet there might be 1B species. That is why this study is so important.”

2021-08-06: The database currently holds 10m barcodes mapped to 330k species.
2022-07-15: Evolution isn’t a tree

“If the evolutionary history of the hoatzin conformed to processes we already understand well, then we’d probably have already figured out what it is most closely related to. The fact that we don’t know its nearest relative suggests that there were processes involved that we still do not understand.” The hoatzin could have more than 1 set of closest relatives— “an unsettling prospect in the context of existing classification and in the minds of many contemporary biologists.”

This strange-sounding state of affairs is not unique to the hoatzin; we see it in our own DNA. Human beings share their most recent common ancestor with chimpanzees and bonobos, but more than 10% of the human genome is actually more closely related to the gorilla genome. Another tiny fraction of the human genome also seems to be most closely shared with an even more distant relative: the orangutan. “This implies that there is no such thing as a unique evolutionary history of the human genome. Rather, it resembles a patchwork of individual regions following their own genealogy.”

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