Taxonomy & Evolution

As an inquiring field biologist, it would be difficult not to have an interest in taxonomy and evolution, though for some this may not extend far beyond their immediate speciality – such as plants. Personally, I find the wider picture fascinating – and it gets clearer but more complicated all the time.

It is a long time since the simple idea of kingdoms like plants, animals, fungi and protists was good enough and by the early 2000s about six supergroups were accepted (versions varied). These included

• Opisthokonta which included animals, fungi, and several protist lineages
• Archaeplastida with primary plastids – the photosynthetic organelles deriving directly from cyanobacteria by endosymbiosis. The three main groups were green algae and land plants, red algae, and glaucophyte algae.
• Amoebozoa which included free-living amoeboid forms with lobose pseudopodia (e.g. Amoeba) but also some flagellates, and various slime moulds.

Further molecular work, mostly on newly discovered protists, has transformed our understanding of protist and hence eukaryote diversity.

A recent publication (Burki et al., The New Tree of Eukaryotes, Trends in Ecology & Evolution (2019) https://doi.org/10.1016/j.tree.2019.08.008) sets out a current view like this:

Eukaryotic Tree of Life 3.1

where Chloroplastida includes green algae + land plants, Rhodophyta (red algae), and Glaucophyta, and opisthokonts includes animals, fungi, and their respective unicellular relatives. So there is considerable consistency with the previous version for these familiar groups; the major explosion in diversity at a basic level is amongst the “protists”. This scheme seems likely to be far from the “final” answer.

I suspect it will be a while before opisthokonts becomes a household word….. and don’t let us even start on prokaryotes…….

Tags: Plants