Reconstructing Phylogenies: Phenetic methods

There are basically two methodologies by which phylogenies can be reconstructed: phenetic and cladistic. The latter is based on Hennigian systematics – i.e. characters (apomorphies, plesiomorphies, etc.), while the former is based on distance. I’ll explain what this means in a bit. Cladistics is the norm for morphological systematics, where …

German Idealism and Systematics

This post is about how Naturphilosophie, the natural science branch of German idealism, was expressed in systematics back in the first third of the 19th century. Reads those two links as background knowledge, if needed. The idealists (the natural scientists who followed Schelling and Oken‘s idealism) were also trying to …

Can all genes be swapped by HGT?

Horizontal gene transfer (HGT), also called lateral gene transfer (LGT), is the process by which genetic information is transferred directly to unrelated cells, in contrast to vertical gene transfer, which is the classic parent-to-offspring heritability. It is undoubtably important in unicellular organisms, be they eukaryotic (Keeling & Palmer, 2008) or …

Molecular Clocks, Part 4: Usefulness?

We’ve looked at the theory behind the molecular clock and at some results obtained using it. We saw that they don’t match the fossil record. But is this necessarily a bad thing or is it expected? This diagram (from the modern bird molecular clock paper [Free PDF!] I quoted earlier) …