Evolution of the Horse

[Telstra Robs]

I was wondering if anyone had any links or information regarding refuting "macroevolution" of the horse.

Thankyou,

Telstra Robs

[derrick09]

Here are a couple of links that may be helpful. I think both of them mention briefly about horse evolution.

http://www.godandscience.org/evolution/locke.html

http://www.godandscience.org/evolution/evolution.html

[Telstra Robs]

Thanks, but if you had any specific examples (with explained reasons) that would be great.

Thanks

[zoegirl]

I had, a few years ago, found a new research artice tht discussed the phylogeny of the horse. I will see if I can find it. They wrote that new DNA evidence meant that the family tree was trimmed and there were fewer species . That is one of the frustrations when looking at fossils, you don't really know whether they were the same species or not. DNA evidence can show the number of differences between the fossils.

[adocus]

Actually, DNA is no better than morphology, in that there is no clear number of genetic differences between valid species - it is still a rather arbitrary thing. Since evolution proceeds one single point mutation at a time (ignoring the huge jumps caused by homeobox genes, splicing, etc) there still has to be an arbitrary point at which we say "Here there is enough difference" to call something a different species.

The paper on Equus suffered from several methodological flaws, not the least of which was mistaking a bone from a modern horse for a fossil, which badly skewed the results.

Addy

[adocus]

The article you are looking for was this one:

Evolution, Systematics, and Phylogeography of Pleistocene Horses in the New World: A Molecular Perspective

by

Jaco Weinstock, Eske Willerslev, Andrei She2, Wenfei Tong, Simon Y.W Ho, Dan Rubenstein, John Storer, James Burns, Larry Martin, Claudio Bravi, Alfredo Prieto, Duane Froese, Eric Scott, Lai Xulong, Alan Cooper

Abstract: The rich fossil record of horses has made them a classic example of evolutionary processes. However, while the overall picture of equid evolution is well known, the details are surprisingly poorly understood, especially for the later Pliocene and Pleistocene, c. 3 million to 0.01 million years (Ma) ago, and nowhere more so than in the Americas. There is no consensus on the number of equid species or even the number of lineages that existed in these continents. Likewise, the origin of the endemic South American genus Hippidion is unresolved, as is the phylogenetic position of the “stilt-legged” horses of North America. Using ancient DNA sequences, we show that, in contrast to current models based on morphology and a recent genetic study, Hippidion was phylogenetically close to the caballine (true) horses, with origins considerably more recent than the currently accepted date of c. 10 Ma. Furthermore, we show that stilt-legged horses, commonly regarded as Old World migrants related to the hemionid asses of Asia, were in fact an endemic North American lineage. Finally, our data suggest that there were fewer horse species in late Pleistocene North America than have been named on morphological grounds. Both caballine and stilt-legged lineages may each have comprised a single, wide-ranging species.

Source: PLoS Biol 3(8): e241. doi:10.1371/journal.pbio.0030241

[zoegirl]

thnanks, I had forgotten to check on this!!!

[adocus]

One of the major problems with the Weinstock et al paper was that they chose Equus lambei as one of their few fossil horses to analyze. Equus lambei is not a fossil, it is a modern domestic horse. The type, a skull ans jaws, has bit wear on the teeth. It is largely on this basis that they say that all the New World horse are actually caballine horses.

Addy