Ring species in the making.
Posted on 06/08/2004 3:30:58 AM PDT by PatrickHenry
Paraphrasing the immortal words of that D-Day veteran who responded to smart assed TV news guy, as played continually on Imus Monday AM: "Up your Seventh Planet!"
;-)
I checked, and "uranus.com" isn't available for registration. So it looks like someone's got uranus.
Different species...cannot interbreed and create fertile offspring.
Question:
Are all dogs of the same species?
If not, where do they draw the lines between different "species" of dogs? Most dogs can interbreed and produce fertile offspring, but I just can't imagine a Saint Bernard and a chihuahua... They are both dogs, but are they of the same species?
I just can't imagine a Saint Bernard and a chihuahuaI think it's a sign of good mental health not being able to imagine that :p ... However, they can still interbreed and indeed create fertile offspring, even if the 'act' itself has become somewhat cumbersome due to the enormous difference in size.
The various dog breeds we have are very recent, from a evolutionary perspective, so they have yet to speciate. Given enough time I don't think many biologists would disagree that the Saint Berhard and Chihuahua are likely subjects for speciation though :)
That is amazing. I learn something new every day!
Thanks for the information.
I've read that it's only possible if the female is the St. Bernard. She's large enough to produce live offspring. But a female chihuahua, assuming she somehow survives an encounter with a male St. Bernard, isn't be large enough to drop the resulting litter. Otherwise, I think that at the genetic level the mating is no problem at all.
Very interesting.
I wonder what the pups resulting from such a union would look like.
Nawww, this is a done deal. It joins the "new" species, or "gonna be a new" species pool. This pool contains Nereid worms, primroses, Drosophila paulistorum et al., Lake Nagubago cichlids, mice somewhere in New England etc. etc. And then again there is "nothing new" under the sun.
A fundamental goal in speciation research has been to determine the number of genes that contribute to barriers to gene exchange (or reproductive isolating mechanisms) between closely related species. Recent studies of two particular barriers to gene exchange, hybrid male sterility and female species preferences, have found that these characters are often highly polygenic, with many regions of the genome being associated with at least some effect (for reviews see refs. 1-4). Hybrid male sterility appears particularly highly polygenic when segments of one species are experimentally introgressed into the genetic background of another and made homozygous (e.g., refs. 5 and 6). Perhaps the most extensively studied groups for these characters have been the two races of Drosophila melanogaster and the three species of the Drosophila simulans clade; D. simulans, D. mauritiana, and D. sechellia, although many other species (including non-Drosophila) have also been investigated. However, these species may be atypical of Drosophila species in particular or species in general, because all the hybridizations studied involved homosequential taxa: taxa not differing in their gene arrangements
St. Barnard - Chihuahua: A ring species in the making.
Ring species in the making.
Wait - Gulls are no ring species:
The Herring Gull complex, consisting of some 20 species of so-called large white-headed gulls, has long been considered as the classic example of a ring-species whereby the ring was finally closed by the Herring Gull Larus argentatus invading NW.Europe from America. In a study based on mitochondrial DNA, Dr.'s Dorit Liebers, Peter de Knijff and Andreas Helbig show that this is not the case. In fact the ring was never closed and they predict that should it ever happen then the most likely scenario is that the Lesser Black-backed Gull Larus fuscus will settle in the New World where it's numbers have increased dramatically in recent times. Instead of one they have found two ancient refugia, an Atlantic and an Aralo-Caspian one from where gulls spread eastwards into the Mediterranean and into the Americas respectively.
source: Dorit Liebers, Peter de Knijff and Andreas Helbig. 2004. The herring gull complex is not a ring species. Proc.Royal Soc.Lond. 10.1098/rspb-2004.2679 (2004).
Here's a bit more.
Recent genetic study sheds light on the evolution of the Herring Gull complex
As reported in the May 2004 issue of Birding World, a recent genetic study (Liebers, de Knijff, and Helbig 2004) has shed some fascinating light on the evolution of the Herring Gull complex, and incidentally therefore on the relationships of some of the larger larids of South Korea.
The authors studied the mitochondrial DNA variation of 21 large gull taxa in an attempt to reconstruct their evolutionary history. Contrary to the expected "ring species" model, members of this complex apparently differentiated largely in geographical separation, not through isolation-by-distance. The divergence started from two glacial refugia, one in the North Atlantic and one in the Aral-Caspian region. Great Black-backed Gull Larus marinus, Yellow-legged Gull L. michahellis, Armenian Gull L. armenicus, and Herring Gull L. argentatus all originated from the North Atlantic refugium. However, the Lesser Black-backed Gull group (including - according to the authors - heuglini and barabensis), Caspian Gull L. cachinanns and a Pacific-North American clade (consisting of vegae, mongolicus, schistisagus, glaucoides, thayeri, and smithsonianus) derive from the Aral-Caspian refugium: it has only been this latter group that has attained circumpolar distribution.
Pesky DNA.
You evolution religionists are incredibly defensive. Where did I ever say that I disputed the findings? Or was even interested in doing so? I know that I cannot change your faith and I know that you cannot change mine. I know that God will use whatever methods (including natural selection) He chooses to use to fill any niche that needs to be filled. (I guess you could put me firmly in the creationist/intelligent design group)
However, none of that affects my original statement that the article was improperly worded or uses a definition of "prefers" that is not accurate. Whether or not the science is done correctly the report still should be written to make sense and eliminate confusion.
Missed this earlier and I think it deserves a response. I would object because blacks and whites can interbreed with no problems. There's not enough genetic difference for them to be considered different species. Other than external characteristics (color mostly) I don't know of anything else that is different. Same blood types etc. There is only the human species, not the white species or black species.
Educate me a little. Ring species? Hadn't seen the term before.
The various Ensatina salamanders of the Pacific coast all descended from a common ancestral population. As the species spread southward from Oregon and Washington, subpopulations adapted to their local environments on either side of the San Joaquin Valley. From one population to the next, in a circular pattern, these salamanders are still able to interbreed successfully. However, where the circle closes -- in the black zone on the map in Southern California -- the salamanders no longer interbreed successfully. The variation within a single species has produced differences as large as those between two separate species
pretty cool. Thanks.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.