Date: Sun, 9 Feb 2003 14:30:56 -0500 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: Walter Ellison Subject: Re: Bird Orders MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Hi All, I pretty much agree with what Dennis Coskren and Bill Ellis said about the use of the (Charles, no-relation-to David) Sibley and Ahlquist DNA hybridization results. However, I wish to clarify something that wasn't specifically mentioned in the discussion. The AOU accepts a lot of the Sibley & Ahlquist taxonomy at the *family level*. The orders proposed by Sibley & Ahlquist have been less accepted. This is because Charles Sibley chose an arbitrary cutoff from his DNA "melting" temperature measures to define orders that has little to do with other ways of establishing who is related to who, such as form, function and shared characters (Sibley's measure is based on overall similarity/disimilarity in the the entire mass of genetic material, each bird species' genome). There is not a whole lot of agreement on an objective measure for defining orders, as such it's best to leave most orders in place. The Sibley & Ahlquist data actually break up very few bird orders (New World Vultures have proven just too closely related to storks to ignore), and their lumping of orders was arbitrary and based on only one, admittedly comprehensive, set of data. Good Birding (& Stay Warm when you're indoors), Walter Ellison MD-DC Atlas Coordinator - MOS 23460 Clarissa Road Chestertown, MD 21620 phone: 410-778-9568 e-mail: rossgull@crosslink.net "A person who is looking for something doesn't travel very fast" - E. B. White (in "Stuart Little") ----- Original Message ----- From: "Jane & Dennis Coskren" To: Sent: Sunday, February 09, 2003 1:49 PM Subject: Re: [MDOSPREY] Bird Orders > Hi-- > The new taxonomy is that of Charles Sibley and Burt Monroe ("Distribution > and Taxonomy of Birds of the World", published in 1990). It's based on DNA > hybridization studies by Sibley and Ahlquist. I don't think it's been > universally adopted; in particular, I don't know if it's been adopted by the > AOU. It is probably a much closer approach to the true relationshps of the > groups than is the old classification. > TDCoskren ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= =========================================================================