Path: utzoo!utgpu!attcan!uunet!lll-winken!csd4.milw.wisc.edu!mailrus!ncar!tank!ogil From: ogil@tank.uchicago.edu (Brian W. Ogilvie) Newsgroups: sci.bio Subject: Re: embryology. A mini tutorial Message-ID: <2844@tank.uchicago.edu> Date: 21 Apr 89 19:25:58 GMT References: <3229@imagen.UUCP> <169@ascom.UUCP> <1957@trantor.harris-atd.com> Reply-To: ogil@tank.uchicago.edu (Brian W. Ogilvie) Organization: History of Science, University of Chicago Lines: 28 In article <1957@trantor.harris-atd.com> hnewstrom@x102a.harris-atd.com (Harvey Newstrom) writes: >In article <169@ascom.UUCP> rene@ascom.UUCP (Rene Bach) writes: >>[....] >>The only pair of chromosomes that look different is the SEX chromosome pair. >>XY = males and XX for females (valid in many species but I believe not ALL). >> >>Rene Bach >>Switzerland > >Obviously only valid for sexual (not asexual) creatures. The latest issue of NATURAL HISTORY (May 1989) has a fascinating article on a hybrid parthenogenetic lizard found in South America. As it originated from the mating of two different (albeit closely related) species, very few of its chromosomes look the same, although they are similar enough for synapsis to occur reliably. The article focused on the two species from which the hybrid originated. Only one of them is known; the other was predicted from the chromosomal configuration of the hybrid. When the hypothesized species is discovered it will be perhaps the first species whose existence was predicted before its discovery (at least, the first one predicted to such precision; Ernst Haeckel predicted Pithecanthropus years before it was discovered by one of his former students). -- Brian W. Ogilvie / ogil@tank.uchicago.edu "Cartesianism is the most popular 'popular science' ever invented." --Noel Swerdlow