return to main index

  mobile - desktop
follow us on facebook follow us on twitter follow us on YouTube link to us on LinkedIn
 
click here for  Animal Specialties
Mice, Rats, Rabbits, Chicks, Quail
Available Now at RodentPro.com!
Locate a business by name: click to list your business
search the classifieds. buy an account
events by zip code list an event
Search the forums             Search in:
News & Events: Herp Photo of the Day: Happy Rattlesnake Friday! . . . . . . . . . .  ACTION ALERT: MI introduces "dangerous animal" legislation . . . . . . . . . .  Herp Photo of the Day: Kingsnake . . . . . . . . . .  The Reptile Expo - Dec. 12, 2020 . . . . . . . . . .  Northern Virginia Reptile Show - Dec. 12, 2020 . . . . . . . . . .  DFW Herpetolocial Society Meeting - Dec. 19, 2020 . . . . . . . . . .  All Maryland Reptile Show - Dec. 19, 2020 . . . . . . . . . .  York County Reptile Show - Dec. 20, 2020 . . . . . . . . . .  Show Me Reptile & Exotics Show - Jan. 02-03 2020 . . . . . . . . . .  All Maryland Reptile Show - Jan. 09, 2021 . . . . . . . . . .  Reptiles At The York Expo Center - Jan. 16, 2021 . . . . . . . . . .  All Maryland Reptile Show - Feb. 06, 2021 . . . . . . . . . .  York County Reptile Show - Feb. 07, 2021 . . . . . . . . . . 

full banner - advertise here .50¢/1000 views
click here for The Turtle Source
pool banner - $50 year

RE: Polyphyletic

[ Login ] [ User Prefs ] [ Search Forums ] [ Back to Main Page ] [ Back to Taxonomy Discussion ] [ Reply To This Message ]
[ Register to Post ]

Posted by: CKing at Sun Sep 28 07:23:44 2008  [ Report Abuse ] [ Email Message ] [ Show All Posts by CKing ]  
   

>>Hypothetical taxon: frogs birds
>>
>>Is this a polyphyletic group, or is it paraphyletic?
>>
>>Thanks.

If this taxon consists only of frogs and birds, then it is considered polyphyletic by any systematist, whether he/she is a cladist, a pheneticist or a Darwinian.

The closest living relatives of frogs are salamanders and caecilians. Thus frogs, salamanders and caecilians have a nearest common ancestor that is different than the common ancestor of the birds and frogs. The closest living relatives of birds are the crocodilians, and of course birds are also more closely related to the reptiles and even the mammals than they are to the frogs. The common ancestor of the birds, mammals and reptiles is the common ancestor of the amniotes. The common ancestor of the frogs, salamanders and caecilians is the common ancestor of the lissamphibians.

Therefore a taxon consisting or birds and frogs only would consist of one group from the amniotes and one group from the lissamphibians. That taxon would of course be unambiguously polyphyletic, no ifs, ands, or buts about that.

The common ancestor of the frogs and birds is also the common ancestor of the tetrapods. If one removes frogs (a crown group) from the tetrapods and puts them in a new higher taxon, the remaining tetrapods (excluding frogs) is a basal group that lacks some of the crown groups. Such a group (i.e. the basal tetrapods) would be considered paraphyletic by the cladists. The Darwinians and pheneticists, however, do not make a distinction between paraphyletic and monophyletic groups. Therefore the basal tetrapods (excluding the frogs) would be considered monophyletic by Darwinians and pheneticists. If one then removes birds (also a crown group) from the remaining tetrapods and classify the birds as another higher taxon, then the remaining tetrapods (excluding frogs and birds) would again be paraphyletic according to the cladists but monophyletic according to the Darwinians. But if one lumps frogs and birds (2 different crown groups with different common ancestors) into a single taxon, the such a taxon would be polyphyletic according to the Darwinians, the cladists, or the pheneticists.


   

[ Reply To This Message ] [ Subscribe to this Thread ] [ Show Entire Thread ]


>> Next Message:  RE: Polyphyletic - apeltes, Mon Sep 29 01:18:40 2008

<< Previous Message:  Polyphyletic or Paraphyletic? - apeltes, Thu Sep 11 16:34:00 2008