The
tree of life was first thought of in 1859 when Charles Darwin wrote “On the
Origin of Species”, since than the tree of life has been studied and
referenced, theoretically that is. The invention of DNA sequencing was first to
change the way scientist theorized the tree of life. This was because DNA
sequencing let scientist find the relationship between species through their
genes. It was not until 1970 when Carl Woese of the University of Illinois and
his colleagues first published a “universal tree of life”, which was presented
with the three main trunks we all know, eukaryotes, bacteria, and archaea. When
scientist wanted to add new species to the tree they faced a challenge because
they did not know how to grow many of the single celled organisms in the lab.
Researchers however, developed a way to conquer this challenge, by pulling
pieces of DNA from the environment and piecing them together.
Jillian
F. Banfield of the University of California, Berkeley and her colleagues have
been using the DNA piecing together technique for awhile now and have assembled
genomes of hundreds of microbial species. The problem now was to figure out
where they fit into the tree of life. Their solution was to redraw the tree.
This was done by selecting more than 3,000 species to study, which gave them a
large enough sample of diversity, and studied DNA form 2,072 known species
along with DNA from 1,011 species of newly discovered. With their new data they
used a supercomputer to evaluate the possible number of new trees. They
eventually found the one that best supported their evidence, which is the one
presented today. With the new tree it shows how much bacteria have been over
showed by the close relationship between eukaryotes and archaea.
This
new tree can present new questions for scientists and brings a whole new look
at life’s evolution. I never thought I would see something that has been looked
at and taught the same for so many years. I grew up with almost all of my
science classes presenting the same tree and giving the same evidence, but now
there is a new perspective.
My first thought when looking at this tree is that its upside down. Might seem a little ridiculous, I know, but I'm sort of picturing the bacteria as what would the roots of the tree and then everything else is sprouting out of that. Just something to think about.
ReplyDeleteI like how the Eukaryotes are at the "bottom" of the tree. It's nice to be reminded that everything is evolving at the same time, and that just because we are more complex does not make us evolutionarily more advanced than bacteria. If they hadn't undergone adaptation and change, they would not be as widespread as they are or as diverse as this tree shows. It's interesting.
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