22 July 2005

Cladistics at 30,000 feet: from cladograms to cloudograms

While flying back from Florida this afternoon I studied cladistics from Cladistics by Kitching et al. So there I was in a window seat immersed in the book while the plane rose above the clouds. At one point, I glanced out the window and saw these peculiar vertical patches of clouds. They immediately reminded me of the terminal taxa in the cladograms that I had been struggling to understand.

In a cladogram (below) the terminal taxa are distinguished from each other by the characters that are unique to them, such as the characters 5-9 in the lizard, 10 in the salmon, 11 in the shark and 12 in the lamprey. In the cladistic jargon, such characters are known as autapomorphies. In a cloudogram (above) there are, of course, no autapomorphies, all the branches have the same "characters". Nevertheless, they are pretty.

Figure from Kitching et al., Cladistics.

1 comment:

menvall said...

You're right. Terminal taxa are inconsistent with clades. Cladistics is self-contradictory ambiguous, that is, paradoxical.