Thursday, August 04, 2011

Taxonomically not what you eat

One should be cautious in naming a taxonomic group for their ecological habits.

I offer you these examples:

1. Most turtles are amphibious; all are reptiles, not amphibians. Turtles have scales, lay hard leathery eggs, have the physiological and genetic makeup of reptiles. I often see phrases such as, "turtles and other Amphibians" in writing about biology by non-scientists. The taxonomic term 'amphibians' is not helpful in getting across to people that turtles are reptiles.

2. Consider the Carnivora. Most Carnivora are carnivores, but some, such as the giant panda, eat largely plants. Further, many carnivorous mammals are not Carnivora in the taxonomic sense. Unnecessarily confusing.

3. Pity the poor Insectivora. It turns out things are worse than just dietary nonconformity (not all the Insectivora ate insects, and not all insectivorous mammals were called Insectivora). The group called Insectivora no longer exists! Biologists had assumed that similarities in diet and morphology among the moles, shrews, tree shrews, golden moles, hedgehogs, moonrats, solenodons, tenrecs, elephant shrews and colugos were the result of common descent (they all had these traits because they were all closely related to each other). It is now clear that Insectivora was an ecological rather than taxonomic grouping. This is because modern molecular genetic and phylogenetic methods make clear that most of these Insectivores are not any more closely related to each other than they are to you, or to an elephant. Specifically, the moles, shrews, solodons, hedgehogs and moonrats form one group, whose closest relatives include the carnivores and hoofed mammals. The tree shrews and culogos (of southeast Asia) are more closely related to the primates. The golden moles, tenrecs and elephant shrews (all African groups) are related to larger mammals found in Africa such as the aardvarks and elephants.

4. The Caprimulgidae (Latin for goat suckers), do not suck goats. They were named for a feeding behavior falsely attributed to them. They are in fact insectivores.

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