Oct 16 2008
Family Resemblance
The last time I was in the Everglades I enjoyed training my binoculars on the purple gallinules and watching them stride atop lily pads. They used their almost comically long toes to distribute their weight. My own nickname for this species is “the Jesus bird.”
A few years later I went birdwatching at the nearby Lake Woodruff National Wildlife Refuge, where I took the above photo of a common moorhen. While looking at that bird through binoculars, I said to my wife, “boy, the moorhen looks a lot like the purple gallinule . . . or vice versa.” And indeed, they are closely related species, both belonging to the rallidae or “swamp hen” family.
In past centuries species were classified according to how much they resembled one another. Granted, that resemblance was based on things more than skin deep, especially skeletal structure.
I’m no evolutionary biologist, but it seems to me that scientists are now relying more on DNA comparisons to determine, at least partly, how closely two species may be related.
You have no doubt heard that Pan troglodytes (chimpanzees) and Homo politicus* (my classification – politically active upright apes) share roughly 98.5% of their genes.
Sometimes related species have a “family resemblance.” Other times the resemblance is not obvious. One example is the freshwater manatee that winters in the springs not far from my home. It is thought that this swimming, air-breathing mammal evolved from an ancestral . . . elephant. Okay, I can see it in the wrinkly gray skin and the small eyes . . . but otherwise, wow! What a surprise.
Ultimately, we are all related. So go out and hug a tree today. And a toad. And some fungus. And . . .
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[* Damn -- I thought I had been original, but a quick web search reveals that someone beat me to the punch and actually published a book by the title, Homo Politicus: The Strange and Scary Tribes that Run Our Government.]
[...] Several were submitted this time. Starting the evolution themed posts off, the evolving mind has Family Resemblance and Grrlscientist tells us what the ‘Fishapod’ Fossil Provides More Clues for the [...]