bwood@janus.Berkeley.EDU (Blake Philip Wood) (01/30/90)
I'm aware that the inability to interbreed is the standard definition
of two populations being of differing species, but more precisely,
is it:
a) can't physically mate due to differing genitals.
b) could, but don't mate due to differing sexual lures, rituals, etc.
c) can mate but produce no offspring.
d) can mate but produce sterile offspring, ie. horse+donkey=mule.
or is it several of the above?
Blake P. Wood - bwood@janus.Berkeley.EDU
Plasmas and Non-Linear Dynamics, U.C. Berkeley, EECSfrazier@oahu.cs.ucla.edu (Greg Frazier) (01/30/90)
In article <33962@ucbvax.BERKELEY.EDU> bwood@janus.Berkeley.EDU.UUCP (Blake Philip Wood) writes: >I'm aware that the inability to interbreed is the standard definition >of two populations being of differing species, but more precisely, >is it: > >a) can't physically mate due to differing genitals. >b) could, but don't mate due to differing sexual lures, rituals, etc. >c) can mate but produce no offspring. >d) can mate but produce sterile offspring, ie. horse+donkey=mule. Unfortunately, it is all of these and more. For example, we are currently trying to breed Lamprologus pulcher, a species of fish from Lake Tanganika. These fish are, for all intents and purposes, identical to L. brichardi, even to the point of breeding. The offspring of such a pair breed true, i.e. each fry will be either a L. pulcher or a L. brichardi. Taxonomists have differentiated between the species based upon subtle differences in scale colorings, although I have also heard that they are different temperamentally (pulchers are supposedly more aggressive). I know, this sounds like splitting human beings into different species based upon eye color, but there it is - don't blame me, I'm not into taxonomy. Greg Frazier ................................................................ "They thought to use and shame me but I win out by nature, because a true freak cannot be made. A true freak must be born." - Geek Love Greg Frazier frazier@CS.UCLA.EDU !{ucbvax,rutgers}!ucla-cs!frazier
dmark@acsu.Buffalo.EDU (David Mark) (01/30/90)
In article <33962@ucbvax.BERKELEY.EDU> bwood@janus.Berkeley.EDU.UUCP (Blake Philip Wood) writes: >I'm aware that the inability to interbreed is the standard definition >of two populations being of differing species, but more precisely, >is it: > >a) can't physically mate due to differing genitals. >b) could, but don't mate due to differing sexual lures, rituals, etc. >c) can mate but produce no offspring. >d) can mate but produce sterile offspring, ie. horse+donkey=mule. > >or is it several of the above? > It is several of the above, and more. It also could be: e) can mate, and produce fertile offspring, but those offspring have strong selective disadvantages, and don't succeed in producing as many offspring of their own as a non-hybrid would. f) can mate, and produce healthy, vigorous, fertile offspring, but the next generation after that has selective disadvantages. The current "biological species" model popularized by Ernst Mayr, just is concerned about whether forms *DO* interbreeed freely in the wild, not whether they can. A commonly used example is the ducks, Mallard (Anas platyrhinchus) and Pintail (Anas acuta). Hybrids are very rare in the wild, and they overlap through most of the Pintail's breeding range. In captivity, in the absence of same-species, opposite-sex, they will freely interbreed. The young, and subsequent generations apparently are fully fertile and viable. They are separated normally in the wild by different courtship rituals, etc. In the Mayrian view, two forms should not be lumped if both parental types occur throughout the overlap zone. For other groups, especially plants, the Mayrian definition is not really applicable. Systematic botanists tend to use a morphological species definition more often. David Mark > Blake P. Wood - bwood@janus.Berkeley.EDU > Plasmas and Non-Linear Dynamics, U.C. Berkeley, EECS
samaddar@demon.siemens.com (Sumitro Samaddar) (02/01/90)
Are all dogs in the same species?
howard@53iss6.Waterloo.NCR.COM (Howard Steel) (02/01/90)
In article <22448@siemens.siemens.com> samaddar@demon.UUCP (Sumitro Samaddar) writes: >Are all dogs in the same species? NO. The main problem is usually physical disparity. When's the last time you saw a St. Bernard - Chihuahua cross? -- / / / / / / / / / / :-(I Think, Therefore I Am, I Think :-) / / / / / / / / / / / Howard.Steel@Waterloo.NCR.COM NCR CANADA LTD. - 580 Weber St. N / / (519)884-1710 Ext 570 Waterloo, Ont., N2J 4G5 / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
turpin@cs.utexas.edu (Russell Turpin) (02/02/90)
In article <202@53iss6.Waterloo.NCR.COM>, howard@53iss6.Waterloo.NCR.COM (Howard Steel) writes: >> Are all dogs in the same species? > > NO. The main problem is usually physical disparity. When's the last time you > saw a St. Bernard - Chihuahua cross? But a St Bernard will happily breed with a large shepherd, which will breed with a medium collie, which will breed with a smallish terrier, which will breed with the Chihuahua. If one uses solely the above criterion for being in the same species, one has the problem that the relation "being in the same species" is no longer transitive. Hence, the concept of a species (as a group) disappears, to be replaced by the comparative but non-transitive relation of breedability. Russell
howard@53iss6.Waterloo.NCR.COM (Howard Steel) (02/02/90)
In article <7757@cs.utexas.edu> turpin@cs.utexas.edu (Russell Turpin) writes: >>> Are all dogs in the same species? >> >> NO. The main problem is usually physical disparity. When's the last time you >> saw a St. Bernard - Chihuahua cross? > >But a St Bernard will happily breed with a large shepherd <etc down to Chihuahua,) >If one uses solely the above criterion for being in the same species, one has >the problem that the relation "being in the same species" is no longer >transitive. Hence, the concept of a species (as a group) >disappears, to be replaced by the comparative but non-transitive >relation of breedability. I agree. The problem is there are so many different critera (from diverse fields) that at some point the concept of species as you point out disappears. What I was employing was a simplistic approach, often employed by anthropologists that the main requirment for a member of a species is the ability to breed viable offspring. In university the argument that you proposed was forwarded, and the reply was something like; " but can a St. Bernard breed with a Chihuahua?" The implication also existed that groups of say people who were physically separated by insurmountable barriers, effectively became different species (a ludicrous concept, I realize). The point is species is a nebulous enough term that it can only be appropriately used within the context of the field specifically being discussed. A Chihuahua is genetically in the same species as as a St. Bernard for example, and theoretically nothing prevents the cross-breeding, except physical constraints. The Chihuahua would probably burst with a litter of St. Bernard, and though the reverse doesn't pose a problem, somebody will have to put the little guy up to it :-). -- / / / / / / / / / / :-(I Think, Therefore I Am, I Think :-) / / / / / / / / / / / Howard.Steel@Waterloo.NCR.COM NCR CANADA LTD. - 580 Weber St. N / / (519)884-1710 Ext 570 Waterloo, Ont., N2J 4G5 / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
davidh@uhccux.uhcc.hawaii.edu (David Helweg) (02/03/90)
In article <202@53iss6.Waterloo.NCR.COM> howard@53iss6.Waterloo.NCR.COM (Howard Steel) writes: >In article <22448@siemens.siemens.com> samaddar@demon.UUCP (Sumitro Samaddar) >writes: > >>Are all dogs in the same species? > >NO. The main problem is usually physical disparity. When's the last time you >saw a St. Bernard - Chihuahua cross? No, I have never seen a St. Bernard - Chihuahua cross. Fortunately, this has little to do with question. All dogs belong to the same species, Canus familiarus, for the taxonomists. This physical disparity might be overcome with a little grant money and a stepping stool.
richard@gryphon.COM (Richard Sexton) (02/04/90)
In article <202@53iss6.Waterloo.NCR.COM> howard@53iss6.Waterloo.NCR.COM (Howard Steel) writes: >In article <22448@siemens.siemens.com> samaddar@demon.UUCP (Sumitro Samaddar) >writes: > >>Are all dogs in the same species? > >NO. The main problem is usually physical disparity. When's the last time you >saw a St. Bernard - Chihuahua cross? Ok, DO TELL US what the different ``dog species'' are. Don't forget the George Basars.
jackson@ttidca.TTI.COM (Dick Jackson) (02/06/90)
OK Chaps, how about cats? Can a house cat breed with any kind of wild cats? Are lions more different from house cats than St. Bernards are from Pekineze (can't spell Chihuahua). Dick Jackson
frazier@oahu.cs.ucla.edu (Greg Frazier) (02/07/90)
In article <9558@ttidca.TTI.COM> jackson@ttidcc.tti.com (Dick Jackson) writes: > >OK Chaps, how about cats? Can a house cat breed with any kind of wild cats? >Are lions more different from house cats than St. Bernards are from Pekineze >(can't spell Chihuahua). > >Dick Jackson Different species. Lions and tigers can mate, but the offspring are mules (so to speak!). There is a species of wild cat which can interbreed with the domestic cat, however. I have no idea what taxonomists have done with it. Greg Frazier .............................................................. "They thought to use and shame me but I win out by nature, because a true freak cannot be made. A true freak must be born." - Geek Love Greg Frazier frazier@CS.UCLA.EDU !{ucbvax,rutgers}!ucla-cs!frazier
andrea@hp-sdd.hp.com (Andrea K. Frankel) (02/07/90)
In article <25520@gryphon.COM> richard@gryphon.COM (Richard Sexton) writes: >In article <202@53iss6.Waterloo.NCR.COM> howard@53iss6.Waterloo.NCR.COM (Howard Steel) writes: >>In article <22448@siemens.siemens.com> samaddar@demon.UUCP (Sumitro Samaddar) >>writes: >> >>>Are all dogs in the same species? >> >>NO. The main problem is usually physical disparity. When's the last time you >>saw a St. Bernard - Chihuahua cross? Sorry, but "species" is biologically defined (check your high school or college biology books). Dogs are all in one species because their offspring are fertile. Physical difficulties notwithstanding - if you (ahem) gathered sperm from a St. Bernard and artificially inseminated a Chihuahua in heat, you would get offspring which were themselves fertile. Andrea Frankel, Hewlett-Packard (San Diego Division) (619) 592-4664 "wake now! Discover that you are the song that the morning brings..." ______________________________________________________________________________ UUCP : {hplabs|nosc|hpfcla|ucsd}!hp-sdd!andrea Internet : andrea@sdd.hp.com (or andrea%hp-sdd@nosc.mil or @ucsd.edu) CSNET : andrea%hp-sdd@hplabs.csnet USnail : 16399 W. Bernardo Drive, San Diego CA 92127-1899 USA
DCS100@psuvm.psu.edu (Dave Schweisguth) (02/07/90)
In article <3251@hp-sdd.hp.com>, andrea@hp-sdd.hp.com (Andrea K. Frankel) says: [much recursive net.litter deleted] >Dogs are all in one species because their offspring are fertile. >Physical difficulties notwithstanding - if you (ahem) gathered sperm >from a St. Bernard and artificially inseminated a Chihuahua in heat, >you would get offspring which were themselves fertile. In fact, the majority of turkeys raised in the U.S. are incapable of natural mating due to the high body weight for which they are intentionally selected. Reproduction takes place by artificial insemination with fresh semen. [Frozen doesn't work ... but that's another story.] If physical inability to mate is a criterion for speciation, the turkey farmers of America create, miscgenate, and exterminate hundreds of millions of different species a year! Neat, eh? I apologize for any relevance this may have lost to rec.pets people, but I'll leave it to followers-up to edit the groups line. _____________________________________________________________________________ / \ | Dave Schweisguth Home: 814-862-0806 dcs100@psuvm.psu.edu | | 406 Althouse Laboratory Work: 814-863-2791 America Online: Von Mordo | | University Park, PA 16802 FAX: 814-865-2413 GEnie: D.SCHWEISGUT | | | | "When choosing between two evils, I always like to take the one I've never | | tried before." -- Mae West | \_____________________________________________________________________________/
werner@aecom.yu.edu (Craig Werner) (02/07/90)
In article <31579@shemp.CS.UCLA.EDU>, frazier@oahu.cs.ucla.edu (Greg Frazier) writes: > In article <9558@ttidca.TTI.COM> jackson@ttidcc.tti.com (Dick Jackson) writes: > > > >OK Chaps, how about cats? Can a house cat breed with any kind of wild cats? > > are mules (so to speak!). There is a species of wild cat which > can interbreed with the domestic cat, however. > I forget where I read the article, but somebody decided that having a domestic cat with leopard's spots would be really neat. It took about 12-15 years, as I recall, including a few backcrosses, but he succeeded. The progeny is a bit a hybrid, but is considered a House cat with a couple of introduced foreign genes. -- Craig Werner (future MD/PhD, 4.5 years down, 2.5 to go) werner@aecom.YU.EDU -- Albert Einstein College of Medicine (1935-14E Eastchester Rd., Bronx NY 10461, 212-931-2517) "If I don't see you soon, I'll see you later."
debbie@csd4.csd.uwm.edu (Debbie Forest) (02/07/90)
In article <3251@hp-sdd.hp.com> andrea@hp-sdd.UUCP (Andrea K. Frankel) writes: > >Physical difficulties notwithstanding - if you (ahem) gathered sperm >from a St. Bernard and artificially inseminated a Chihuahua in heat, >you would get offspring which were themselves fertile. well, no, you'd probably actually get an exploding chihuahua, but... :-) yes, all dogs are the same species. but why then aren't wolves in the species too, since dogs and wolves can cross-breed?
ggw@wolves.uucp (Gregory G. Woodbury) (02/09/90)
In article <2285@uwm.edu> debbie@csd4.csd.uwm.edu (Debbie Forest) writes: >In article <3251@hp-sdd.hp.com> andrea@hp-sdd.UUCP (Andrea K. Frankel) writes: >> >>Physical difficulties notwithstanding - if you (ahem) gathered sperm >>from a St. Bernard and artificially inseminated a Chihuahua in heat, >>you would get offspring which were themselves fertile. > >yes, all dogs are the same species. but why then aren't wolves in the >species too, since dogs and wolves can cross-breed? The simple case of cross-fertilization (with or without fertile offspring) is not sufficient to define a species. The other half of species definition is the ecological niche the new species occupies in comparison to the parent group. When an adaptive shift occurs which allows the offspring to occupy a niche which tends to isolate the new group from the old further adaptations in the new group can accelerate the isolation of the new species. Wolves and Dogs (canis lupus vs canis familiaris) occupy different niches in general, but not so different that contact is eliminated. Some purists would like to say that lupus and familiaris are "sub-species", but general usage has its effect as well. ------------- Just some additional fuel for the discussion to justify being in sci.bio ;-) -- Gregory G. Woodbury Sysop/owner Wolves Den UNIX BBS, Durham NC UUCP: ...dukcds!wolves!ggw ...dukeac!wolves!ggw [use the maps!] Domain: ggw@cds.duke.edu ggw@ac.duke.edu ggw%wolves@ac.duke.edu Phone: +1 919 493 1998 (Home) +1 919 684 6126 (Work) [The line eater is a boojum snark! ] <standard disclaimers apply>