‘The Tree of Life is Messed Up’ ~ YouTube video

The SciShow
produced a YouTube video (below) that discusses the problem with the Linnean (1758, 1766) method of taxonomy (naming clades) that included nested ranks such as phyla, class, order, genus and species. SciShow also described the problems (quirks) inherent in describing groups based on shared characteristics vs the last common ancestor method of assessing monophyly vs DNA results.

DNA results produce false positives
over deep time (not always, but often enough) compared to phenomic (trait-based) studies.

The last common ancestor method
trumps the shared characters method because convergence is rampant in Vertebrata. And no one wants to ‘Pull a Larry Martin.’

A wide gamut online phylogenetic analysis
of vertebrates has been building (1654+ taxa at present) over the past nine years at 
the large reptile tree. It includes extinct and extant taxa from Cambrian lancelets to modern humans enabling one to trace the ancestry of every included taxa and to list all the tested members of monophyletic clades.

This will become important in the next post
as the LRT resurrects yet another clade long thought to be extinct. Extant clade members don’t have some of the ‘key’ characters that characterize this clade. That doesn’t matter because in phylogenetic analysis there are no ‘key’ characters.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.