At 12:16 PM 10/29/2003, Dan Dugan wrote:
>Had to look that one up:
>
>Plesiomorphic: in cladistics, this term describes primitive
>or generalized characteristics that arose early in the evolutionary
>history of a taxonomic group. These will be very widespread and will
>therefore not help in dividing the group into lower-level taxa.
Sorry,
Plesiomorphic traits are traits that have been passed down through earlier=
taxa. They arose in animals which evolved prior to the animal in question,=
and they continue to manifest themselves, usually because they are
effective. In the sense of bird (and other animal) communication, we often=
find certain calls that several different, but related, species use - this=
is a plesiomorphic call - it came from a common ancestor. If you are
familiar with Canyon Towhees and Abert's Towhees, you might hear them both=
use the same complicated duetting call - a call unlike any other bird uses.=
They both inherited it from a previous species.
Our human "Flight or Fight" response is a plesiomorphic trait that we
inherited ultimately from the earliest animals - a very effective tool that=
survived in nearly all animals.
Plesiomorphic calls are important because they indicate how closely related=
taxa are and are sometimes an indication of where a particular species
arose. That's why I pay attention to plesiomorphic vocalizations - they are=
a way to know who's related to whom and how close that relation is.
Doug
Doug Von Gausig
Clarkdale, Arizona, USA
Moderator
Nature Recordists e-mail group
http://groups.yahoo.com/group/naturerecordists
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