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Author | Topic: Ring species as evidence for speciation | |||||||||||||||||||||||
RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
offspring of mixed mating of horses, donkeys and zebras are not fertile, so mating while it produces offspring is not "successful"
we are limited in our ability to understand by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Reference I ran into before on this issue is:
Object reference not set to an instance of an object. The second paragraph is where I got the implication that all crosses were sterile (it is not that clear on re-reading). The whole top section is copied from a book and carries this notice:
Reproduced on the webpage from HORSES THROUGH TIME edited by Sandra L. Olsen with permission of Roberts Rinehart Publishers, 6309 Monarch Park Place, Niwot, Colorado 80503. These excerpts may be read only, any printing or reproduction of this material must be obtained in writing from Roberts Rinehart Publishers. The extinct species is the Onager. Also from:http://www.geocities.com/zedonknzorse/basics.html So cross a ZEBRA to a HORSE and you get a ZORSE! Or a zebra stallion to a donkey jennet (mare) and you get a ZEBRASS (also called a zedonk or zonkey). These too are sterile hybrids, and cannot reproduce. Each mule, hinny, zorse or zedonk/zonkey is a one-time shot. Would be interesting to take one of the occasionally fertile female mule and breed with a zebra, eh? enjoy. we are limited in our ability to understand by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
oops.
The species described as a "wild ass" in the bible should correctly be called an onager, an Asian species intermediate between donkeys and true horses ... Stephen Jay Gould .. suggesting that the three surviving species of zebra may be more closely related to asses and horses than to each other ...
and
http://www.planetfusion.co.uk/~pignut/equines.htmlAn extinct animal that will never be cloned is the quagga. This relative of the horse once roamed the central plains of Southern Africa by the thousands, but the quagga genome is gone. In the 1800s, European settlers shot all the quaggas in the wild. The quagga was seen as an unwanted grazing competitor to the farmers' livestock, as were all the other grass-eating wild animals. The quagga is gone, but quagga genes may have survived. DNA studies in the 1980s suggested that the quagga is a cousin of the plains zebra, which today roams throughout much of Africa. Researchers compared DNA from a preserved quagga hide in a natural history museum to that of a plains zebra and found in each sample the same stretches of genetic code. In South Africa, the Quagga Project Breeds Success my bad. we are limited in our ability to understand by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
are there any instances where all adjacent species can mate but opposite sides can't?
I thought that the fish is Lake Tanganika did that (don't remember the species, a common one, a shallow water fish forming a ring around inside the lake).
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
yep that's the fish. let me sleep on it and I might remember where I saw it.
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Have not found the reference I thought I had.
I did find this on the web:http://www.zoology.ubc.ca/~irwin/PDFs/IrwinIrwin&Price2001 It is a PDF file article on ring species in general and the relation to speciation. If you search the document for "cichlid" you will find 3 references at the end that you may want to track down.
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
my understanding was wrong originally. my last reference has information on the green warbler, and I am gradually wading through it.
I thought all adjacent species were capable of interbreeding, kind of like a quick expansion of a species into a ring around some feature that would physically block diagonal interchange but allow adjacent interchange all the way around, with genetic divergence gradually causing diagonal species to be incompatable (like an open ring species mirrored). the question is on the "circular overlap" or ring species versions talked about are just the end results non-breeding or does that extend down each leg significantly?the case for dogs being a ring species is interesting as what you have is a broad matrix of size and behavior that would be more like an area (map?) than a linear (ring) relationship: it is still possible that varieties on the borders are not interfertile with others on the other side of the "map" and it should also be possible to test the amount of genetic flow between varieties with DNA studies. sounds like a potential thesis subject to me.{added by edit} it also seems to me that this would hold for any species population to some extent, just that it is most extreme in the canines due to human interference. modeling it could add some interesting insights into general population behaviors and speciation potentials. thanks. This message has been edited by RAZD, 01-14-2005 20:32 AM we are limited in our ability to understand by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Loved the article (especially the bird songs links ... I'm a birder ), so thanks again. From your article:
The northern forms are about 10% smaller in body size than the southern forms, and the northern forms inhabit much denser forest at lower elevation than the southern forms. The northern forms also must migrate much further to their wintering grounds in southern Asia. Lower elevation with further north range would be logical in terms of keeping to a similar temperature range I would think, and smaller body size with similar response to climate changes and increased distance needed to migrate ... ie -- both varieties are responding in the same way to the same stimulus for change and selection is giving similar results. Gosh, genetics, behavior, plumage, songs, all follow the same patterns? What a surprise eh? we are limited in our ability to understand by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
cool. do they address the "gap" in china and specifically tie the genetic differences there to be consistent with the whole pattern?
we are limited in our ability to understand by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}
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RAZD Member (Idle past 1434 days) Posts: 20714 From: the other end of the sidewalk Joined: |
great. that was one area I was a little concerned about on this species.
perhaps we just need more information on the degree of change over time on these species to see how recent "recent" is
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