|
|
Joined: Sep 2001
Posts: 6,296
Carpal Tunnel
|
OP
Carpal Tunnel
Joined: Sep 2001
Posts: 6,296 |
Will someone please explain the technical differences between species and breeds to me again?
Let me explain my puzzlement in simple terms:
There are just over 900 species of bats. Helluva lot of species of bats, almost 1/4 of the counted species of mammals. (There are more species of rodents, however.)
Then there are all those breeds of dogs of which I've been thinking because of something AnnaS referred to somewhere else. And I do understand that breeds are different from species.
However, if a poodle mates a poodle--and they are from a registered line of poodles--the result will be a poodle and not a collie.
And I understand that a poodle and a collie can mate thereby producing another dog that is neither poodle nor collie, but still dog.
And I understand that in oaks, at least, that there can be a cross-species pollination occasionally. One kind of oak can conceivably pollinate another and a strange oak will appear.
But *here comes my question:
Is it that among mammals, not one of those bat species can mate with another and produce a new strange bat as can those occasional cross-species oak pollinations?
Does that mean that one species of tiger cannot breed with another species of tiger? (Seems ridiculous. I would think a Siberian could breed with a Bengal, just as a breed of dog could with another...but I'm no biologist.)
So, will somebody please explain this species/breed controversy to me.
Thank you very much.
|
|
|
|
|
Joined: Dec 2000
Posts: 13,803
Carpal Tunnel
|
|
Carpal Tunnel
Joined: Dec 2000
Posts: 13,803 |
Of course we have the problem of applying cubby-hole thinking to a spectrum world. Technically, the defintion of species involves the concept of inter-fertility. This means that if two individuals can mate and have fertile offspring, they are in the same species. Horses and donkeys can mate and have offspring, but the offspring, mules, are not fertile. Darwin's finches strain this definition in that species A and species B are inter-fertile, species B and species C are inter-fertile, species C and species D are inter-fertile, but species A and species D are not inter-fertile. Breeds are of the same species but have been bred for specific characteristics. Offspring of a great Dane and a German shepherd will have characteristics of each in varying amounts and will be completely fertile. The great Dane and the German shepherd are the same species but are different breeds.
|
|
|
|
|
Joined: Sep 2001
Posts: 6,296
Carpal Tunnel
|
|
OP
Carpal Tunnel
Joined: Sep 2001
Posts: 6,296 |
Well, see, Faldage, that's what's bothering me. If you look at all those so-called species of bats, they just look like bats the way dogs look like dogs.
I realize completely that the Great Dane is a breed and that the Scottish terrier is another breed, but they look as unalike as a couple of species of bats. In fact, some of those species of bats look more alike than some breeds of dogs. Think about a collie and a chihuahua, or however you spell chihuahua.
So is it that, yes, some species of bats could conceivably produce baby bats, and, yes, sometimes those bats could conceivably reproduce more baby bats, but sometimes bats can breed and produce bats that can't breed, so, therefore, bats are species and dogs remain dogs that breed like rabbits?
|
|
|
|
|
Joined: Mar 2000
Posts: 1,004
old hand
|
|
old hand
Joined: Mar 2000
Posts: 1,004 |
To add to David's admirable post, I thought I'd simply point out that there is only one species of tiger extant, and the Bengal, Sumatran, Siberian etc are merely breeds of the same. In fact there are only 5 extant species of big cat (allegedly a technical term referring to their ability to roar): tiger, lion, jaguar, leopard and snow leopard. The tiger and the lion have been known, on occasion, to cross-breed, giving rise to (depending upon which was the female parent and which the male) tigons (very large animals) and ligers (rather diminutive compared to the parent species). There have even been reports of these hybrids (the term for the offspring of two different species) being fertile and having produced offspring of their own.
It can be quite surprising when you find out the range of animals that can be considered a single species. For instance, my understanding is that ALL brown bears are members of the same species, from the giant Kodiak breed or sub-species to the much ickler brown bear that roams central and southern America, and Asia.
Also, though the coyote and grey wolf are considered separate species they interbreed very readily, and the product, according to some reports, is the red wolf. This has caused, I understand, some sort of a scandal in environmental circles because of the massive conservation effort in Florida and elsewhere to preserve the red wolf - except it turned out not to be a separate species but a hybrid, after all. (I could be wrong on this one - some years since I read the report in New Scientist?)
To a certain extent, in the past, the human species too could have been considered to be divided into breeds - except that we, unregenerate as we were, called them 'races'. The facts, as I understand them (vide Jared Diamond's Guns, germs and steel), are that while most human populations these days have exchanged genes with their surrounding populations to a great extent, there are still genetic markers that can be identified in groups that have remained isolated, or interbred, for many generations. The original five 'races' of humanity, on the other hand, all originated in Africa, and three of them are still confined to that continent (to a certain extent): the pygmies, the khoi-san and the 'blacks' (typified by the Bantu peoples, and being the stock from which the slavers kidnapped whole populations and shipped them off to the Americas and the Caribbean). In addition, the other two population strands were those that led to 1. the Northern African and Semitic people, and 2. everybody else. The latter have an interesting (at least to us) history, since the original population seems to have spread from Africa to east Asia, forming the basis of what we consider the 'oriental' populations, one strand of which, of course, travelled yet further east, via the Bering Land Bridge and became the 'native' American population. Another strand from east Asia travelled west, acquiring genetic mutations and markers as it went, until it settled down in Europe, to form the basis of what we call the 'white' or 'caucasian' population. So, if you like a neat reversal on racist thinking, being white represents being just one offshoot of an Asian population which itself was an offshoot of the original 5th human group! Another good reference on human population migration and genetic change is Luigi Luca Cavalli-Sforza's Genes, peoples and languages.
Perhaps an overlong response to your query, but I hope it helps.
cheer
the sunshine warrior
|
|
|
|
|
Joined: Mar 2000
Posts: 1,004
old hand
|
|
old hand
Joined: Mar 2000
Posts: 1,004 |
Hi Wordwind
Sorry for a second response so quickly, but thought I needed to address the issue you have raised. You say:
If you look at all those so-called species of bats, they just look like bats the way dogs look like dogs.
It is precisely because of this layperson's view of species that taxonomists have developed more and more refined methods of distinguishing between species (or call them isolated population groups if you wish). That you or I should see a bat and think "just another bat, what's the difference" is irrelevant to the fact of whether or not bats are speciose. We are sensitised to perceive small difference in those phenomena that most directly affect us: other people (our facial recognition systems are remarkably subtle and powerful), pets, domesticated animals, garden plants and so on. Bats, on the other hand, which most of us tend not to live in close proximity to, suffer from the 'they all look the same' fallacy. As might, for instance, various species of termite, or ant.
Cladistics is the most recent, and to some minds, most successful ever method for taxonomic classification. It was devised by the entomologist Willi Hennig in the 1950s. I cannot go into the details of how it works, but read any decent book on evolution (or try the wonderful The variety of life by Colin Tudge), to see its methods and the differences between 'primitive' and 'derived' features (synapomorphies and simplesiomorphies) and so on. If you do get into it, I'm sure you'll find it fascinating. What is worth mentioning, though, is that our intuitions, or common sense, get less and less reliable the further we go from the familiar, and therefore it's not surprising that to most of us, one bat seems pretty much like another.
It makes a huge difference to the various species of bat though. I picture a baby vampire bat suckling at its mother's breast, being homeschooled, and asking her: "Mum, it's all very well to talk about spider monkeys and human beings and the like, but surely a primate is a primate is a primate. They all taste the same..."
cheer
the sunshine warrior
|
|
|
|
|
Joined: Oct 2000
Posts: 5,400
Carpal Tunnel
|
|
Carpal Tunnel
Joined: Oct 2000
Posts: 5,400 |
If you look at all those so-called species of bats, they just look like bats the way dogs look like dogs.
well that's not quite true.. there are two main varieties of bats that i know of.. fruit eaters (who generally don't have 'echo location')-- and meat/insect eaters(who do have echo locations skills.) --or not so bad looking (sort of like the muzzle of a racoon or possum) to butt ugly.. (wrinkles up faces, over sized ears, sharp pointy teeth!)
so some bats are vegitarian, and some are carniverous.. thats a pretty big difference! and it shows in their anatomy. the carniverous ones are the ones with sharp pointy teeth, and they are the ones that use echo location- some find and eat insects on the wing (that is they catch flying insects in mid flight!)fruit eating bats are like small flying monkeys/lemurs or something.
i don't know if these different bats can interbreed (the way, in theory, a great dane could couple with a dashound!)
|
|
|
|
|
Joined: Sep 2001
Posts: 6,296
Carpal Tunnel
|
|
OP
Carpal Tunnel
Joined: Sep 2001
Posts: 6,296 |
Thanks for all the input. I don't think I'm expressing myself well, however. I'm not saying that I don't see differences between bats. That's absurd. If you show me a picture of an animal that is a bat, I would probably identify the animal correctly as being a bat. And so would the rest of us laymen, as you put it. And if you were to ask me to delineate superficial or easily recognizable differences between bat species, I could do that, too, as could other people who used their eyes with discernment. So I'm not idiotically saying that all bats look identical. I'm saying that bats can appear to be similar--oh, lucky for us who want to go bat chasing--and that some bats appear to be more similar in appearance than do some breeds dogs. I took a look at some photographs of bat skeletons, in fact, and those skeletons were remarkably similar in many ways to human skeletons. They were also very different from human skeletons. The similarities were equally interesting to think about as the differences. My whole point here that I'm having great difficulty in expressing is this: What is the defining feature that distinguishes species from breeds? I think probably Faldage has hit upon it--that generally, at least, species are so distinct that the likelihood of breeding between two separate species is low, although I do understand that in some cases species can cross, as in the lion/tiger cases you pointed out. I suppose if you were to leave certain bat species in isolation for a while there would be certain ones that would breed with each other out of boredom or anxiety. Would it be correct to say that species generally breed within each species and that breeds of similar species of animals readily breed with other breeds of that same species of animal? Would it be correct to say that species most likely breed within the species because of geographical proximity, dietary habits (as of troy mentioned), group dynamics, and diurnal and nocturnal proclivities? And would it be correct to say, based on what you have written above, that breeding across species has been well-documented, but it is rare and will often produce infertile offspring, though not always? And, finally, is it to correct to say that superficially, at least, some breeds appear to have more startling differences in appearance than some similar species (i.e., some breeds of dogs look more different from each other than some species of bats)? [I could probably choose two species of dogs that appear to be very different, such as, say, a Newfoundland and a dachshund, and two very similar bat species, such as the hairy-legged vampire bat and the common vampire bat: http://www.scz.org/animals/b/vampire.htmlhttp://www.batcon.org/batsmag/v11n4-14.html...not to mention the Seminole bat that looks a lot like the vampire bats above. *And I'm not saying at all that I can't tell the differences between these bats. I'm just saying that some breeds of dogs have more superficial appearance differences than some superficial appearance differences of some species of bats. Distinctive feature identification is a personal obsession of mine.
|
|
|
|
|
Joined: Dec 2000
Posts: 13,803
Carpal Tunnel
|
|
Carpal Tunnel
Joined: Dec 2000
Posts: 13,803 |
What makes us say that one population is one species and onother population another, apart from the interfertility thing, can be any of a number of features that may or may not be apparent to the eye. It may be details about the way the wing bones articulate. It may be something about muscles in the legs. Looks have very little to do with it. Some marsupials look very much like regular mammals, if you don't bother to check for the pouch, but they would be very far apart if you dug into internal details.
|
|
|
|
|
Joined: Jul 2003
Posts: 3,230
Carpal Tunnel
|
|
Carpal Tunnel
Joined: Jul 2003
Posts: 3,230 |
however you spell chihuahua.
I spell it ratfoetus.
|
|
|
|
|
Joined: Sep 2001
Posts: 6,296
Carpal Tunnel
|
|
OP
Carpal Tunnel
Joined: Sep 2001
Posts: 6,296 |
|
|
|
|
|
Joined: Sep 2000
Posts: 56
journeyman
|
|
journeyman
Joined: Sep 2000
Posts: 56 |
perhaps the answer lies deeper....in the DNA
|
|
|
|
Forums16
Topics13,913
Posts229,316
Members9,182
| |
Most Online3,341
Dec 9th, 2011
|
|
|
0 members (),
621
guests, and
0
robots. |
|
Key:
Admin,
Global Mod,
Mod
|
|
|
|
