kuento@kuhub.cc.ukans.edu (12/12/90)
I realize that this may be taking the discussion far afield from strict molecular biology, but lately I have been participating in many discussions about species concepts and have come up with two ideas I would like to put out for evaluation. The first is that I would like to express solidarity with Endler's view that we utilize more than one species concept (this is expressed in chapter 25 of the volume he edited entitled "Speciation and its consequences". It seems only logical that not one tool will serve to discern all of the biotic diversity that exists. Whether one uses a biological species concept (probably most applicable to ornithologists, since they are the ones who had initially proposed it), phylogenetic species concept (most applicable to paleontologists), recognition species concept (most applicable to many behavioral ecologists?), or some of the other myriad of ideas seems to me to be dictated by the type of data that one can wrest from the organism. As a result, many of these different species concepts have, at their root differences in the manner with which "species" are discerned from ea sequencing, morphology, biogeography, behavior, etc. All of these concepts should of course use cladistics to transform the data into (hopefully) robust evolutionary histories. Secondly I would like to propose the idea that rates of speciation may be site-dependent. Geographical differences also dictate environmental differences which would in turn dictate different selection pressures. The idea that one population will diverge or speciate at the same rate panglobally is absurd, the microclimatic circumstances must be taken into consideration when speculating about speciation rates. Mitochondrial DNA work may lead to misinterpretations of the "truth", since it assumes constant rates of speciation (ie: gradualism) and uniform speciation rates. [I am not disparaging mDNA work, only its universal application. I am sure that organisms that have been in a relatively constant environment would be most effectively analyzed using mDNA] Anyway its something to think about. -- Jim Danoff-Burg (Snow Museum, Univ. of Kansas, Lawrence, KS 66045) Bitnet: KUENTO@UKANVAX
joe@GENETICS.WASHINGTON.EDU (Joe Felsenstein) (12/13/90)
Jim Danoff-Burg writes: > Mitochondrial DNA work may lead to > misinterpretations of the "truth", since it assumes constant rates of > speciation (ie: gradualism) and uniform speciation rates. [I am not > disparaging mDNA work, only its universal application. I am sure that > organisms that have been in a relatively constant environment would be > most effectively analyzed using mDNA] I believe that this is a misconception. I know of no reason to believe that in making mitochondrial DNA phylogenies we are assuming anything about rates of speciation or rates of change of morphological characters. They may or may not assume clocklike change of the molecular sequences, depending on how the analysis is done, but that can of course happen even as the morphology behaves in a most unclocklike way. Perhaps I am missing something -- is it being assumed that the objective of inferring the phylogeny is to assess morphological rates of change or estimate the genealogy? The remainder of the posting is about concepts of speciation. I suggest that it be reposted to the population-biology group which is where that belongs, as it has nothing specific to do with molecular evolution. ----- Joe Felsenstein, Dept. of Genetics, Univ. of Washington, Seattle, WA 98195 Internet: joe@genetics.washington.edu (IP No. 128.208.128.1) Bitnet/EARN: felsenst@uwalocke UUCP: ... uw-beaver!evolution.genetics!joe
JAHAYES@MIAMIU.BITNET (Josh Hayes) (12/15/90)
Interesting you should bring this up now; our normally placid Monday seminar erupted into a rather spirited discussion of the species concept and the value of molecular data. It seems to me that "species" as some sort of Platonic Ideal form has long since passed away. It ought to be admitted that we define things as species in some utilitarian manner, that is, in order to address some particular interest, such as which populations are able to interbreed, and so forth. I would argue that there is no such thing as a species independent of the question we wish to address to the population of organisms under consideration. We've come to realize that the world does not operate under the rigid hierarchical structure that Aristotle proposed, and which has been reified by Linnaeus and those who followed. The world is a continuous (to our perceptions) place; why expect that living things will compartmentalize into a neat discrete classification? (I also wonder where this thread belongs; there is no molecular biology involved thus far, but there is no [or at least we don't receive] bionet.philosophy.evolution. Followups to wherever you think appropriate.) Cheers, Josh Hayes, Zoology Department, Miami University, Oxford OH 45056 voice: 513-529-1679 fax: 513-529-6900 jahayes@miamiu.bitnet, or jahayes@miamiu.acs.muohio.edu "I am the Supreme Being, you know; I'm not completely dim."
Ellington@Frodo.MGH.Harvard.EDU (Deaddog) (12/16/90)
Sadly, I missed the original post, but the responses indicate that it must have been interesting. However, we have: In article <9012131405.AA01263@evolution.genetics.washington.edu> joe@GENETICS.WASHINGTON.EDU (Joe Felsenstein) writes: > The remainder of the posting is about concepts of speciation. I suggest > that it be reposted to the population-biology group which is where > that belongs, as it has nothing specific to do with molecular evolution. In article <90348.121339JAHAYES@MIAMIU.BITNET> JAHAYES@MIAMIU.BITNET (Josh Hayes) writes: > (I also wonder where this thread belongs; there is no molecular > biology involved thus far, but there is no [or at least we don't > receive] bionet.philosophy.evolution. Followups to wherever you > think appropriate.) Given the paucity of traffic on molbio.evolution (indeed, given the tiny number of messages that appear on BIONET in general), we should try to avoid sending interesting strings to their deaths in the hinterlands. Just because it does not fit some anal-retentive's idea of how to divide up the info-bio-sphere (e.g., MOLBIO.YET.ANOTHER.DISPENSABLE.GROUP) does not mean that it isn't worth perusing by folks who like to read about molecular evolution. Alas, poor string, we hardly knew ye .... Non-woof Dept. Mol. Biol. Mass. General Hospital [Extremely offensive .sig available on request, or in response]