>>> I'd be interested in learning of literature that doesn't have Bookstein as one author.
Hi Fred, Although less sophisticated than your methods, I have generated semilandmarks in two ways (papers cited below). Since this has come up on the list, I will take advantage and open my methodology to some hardcore morphometric scrutiny. Method 1: Medial axis technique. In fish I define an axis from the snout to the tail, go every 20 percent along this axis and project at 90� and 270� to the contour intersection, and digitize a semilandmark. FYI, I then use these semilandmarks to test for shape differences among fish of a given species captured or reared in alternative environments. The concept of homology is not very important to me, as I am interested in capturing shape information in an ecological, not systematics context. Method 2: In snails, I have captured the shape of shell apertures by defining landmarks on the top and bottom of the aperture, defining a midpoint between these, and radiating out from this midpoint every 10� to the contour intersections, and digitizing semilandmarks. Again, my interest is in shape per se - I look at aperture shape differences for snails raised with alternative predators. Input from all is welcomed, but I especially would like to hear opinions from Fred (and Jim if he's listening). The papers I referred to (available on request) are: Langerhans, RB, CA Layman, AK Langerhans, TJ DeWitt (In press) Opposite habitat-based divergence in two fishes within a tropical blackwater river. Biological Journal of the Linnean Society. Langerhans, RB, TJ DeWitt (2002) Plasticity Constrained: Overgeneralized environmental cues induce phenotype errors in a freshwater snail. Evolutionary Ecology Research 4: 857-870. -Thom ________________><()()(�>________________ Dr. Thomas J. DeWitt, Assistant Professor Department of Wildlife & Fisheries Sciences & Program in Bioenvironmental Sciences Texas A&M University 2258 TAMU College Station, TX 77843-2258 Tel. (979) 458-1684 (office) Tel. (979) 845-7522 (lab) Fax (979) 845-4096 E-mail [EMAIL PROTECTED] Web http://wfscnet.tamu.edu/wfscnet/facstaff/tdewitt/webpage.htm TAMU Map to DeWitt lab & office: http://www.tamu.edu/map/gifs/detail/FGHB.gif == Replies will be sent to list. For more information see http://life.bio.sunysb.edu/morph/morphmet.html.
