Ewolucja konia

Drogi Mariuszu,   

nie odnalazłem artykułu, który "miałem w głowie", ale być może, że mi się on sam wytworzył.

 

W sprawie ewolucji konia kilka rzeczy wydaje się ciekawych :

1. Od osła i zebry, linia rozwojowa konia oddzieliła się 4 mln lat temu
2. Człowiek na pewno udomowił konia 6 tys. lat temu, na pograniczu Ukrainy i Kazachstanu (takie są wykopaliska)
3. Wydaje się, że wszystkie konie hodowane w Europie pochodzą z dwóch linii, sprzed 700 lat.

Ale to co jest istotne dla abstraktu, który "miałem w głowie", to że DNA mitochondrialne [...]

pokazuje na silne NADpisanie się nowego genotypu jakieś 40-90 tys. lat temu, chyba w Arabii. W ten sposób, wszystkie konie, jak je dziś znamy, nawet te w Ameryce, mogły wędrować za/ z człowiekiem Homo sapiens (to moja, bieżąca hipoteza robocza).

Koń Przewalskiego, jedyny dziki koń na świecie, pozostał od tego momentu z własnym genotypem.

Poniżej abstrakty znaczących artykułów w tym temacie. Powołują sie one m.in. na badania genotypu konia Przewalskiego. A nasz tarpan? Czeka na młodych badaczy...

Odezwę się, jak znajdę coś nowego. 

Grzegorz                                                       

Toruń, 27.01.2018

Alto Adige, wrzesień 2005, foto Maria Karwasz


Recalibrating Equus evolution using the genome sequence of an early Middle Pleistocene horse

Received:30 October 2012

Accepted:30 May 2013

Published online:26 June 2013

Abstract

The rich fossil record of equids has made them a model for evolutionary processes1. Here we present a 1.12-times coverage draft genome from a horse bone recovered from permafrost dated to approximately 560–780 thousand years before present (kyr BP)2,3. Our data represent the oldest full genome sequence determined so far by almost an order of magnitude. For comparison, we sequenced the genome of a Late Pleistocene horse (43 kyr BP), and modern genomes of five domestic horse breeds (Equus ferus caballus), a Przewalski’s horse (E. f. przewalskii) and a donkey (E. asinus). Our analyses suggest that the Equus lineage giving rise to all contemporary horses, zebras and donkeys originated 4.0–4.5 million years before present (Myr BP), twice the conventionally accepted time to the most recent common ancestor of the genus Equus4,5. We also find that horse population size fluctuated multiple times over the past 2 Myr, particularly during periods of severe climatic changes. We estimate that the Przewalski’s and domestic horse populations diverged 38–72 kyr BP, and find no evidence of recent admixture between the domestic horse breeds and the Przewalski’s horse investigated. This supports the contention that Przewalski’s horses represent the last surviving wild horse population6. We find similar levels of genetic variation among Przewalski’s and domestic populations, indicating that the former are genetically viable and worthy of conservation efforts. We also find evidence for continuous selection on the immune system and olfaction throughout horse evolution. Finally, we identify 29 genomic regions among horse breeds that deviate from neutrality and show low levels of genetic variation compared to the Przewalski’s horse. Such regions could correspond to loci selected early during domestication.

 

Most modern horses came from just two ancient lineages | Science ...

BY MICHAEL PRICE | JUN. 29, 2017

Jun 29, 2017 ... Now, a new study finds that nearly all modern horse breeds can be traced to two distinct, ancient Middle Eastern lines that were brought to Europe about 700 ... The new study's lead author, Barbara Wallner, an evolutionary biologist at the University of Veterinary Medicine in Vienna, paired these old, yet ...

http://www.sciencemag.org/news/2017/06/most-modern-horses-came-just-two-ancient-lineages

Horse breeding records are some of the most impressive efforts to chronicle animal lineages in human history, with some stretching back thousands of years. Yet decoding the genetic origins of today’s horses has proved remarkably difficult. Now, a new study finds that nearly all modern horse breeds can be traced to two distinct, ancient Middle Eastern lines that were brought to Europe about 700 years ago. Understanding how these horses were traded, gifted, or stolen could shed light on human history as Eastern and Western civilization commingled and collided.

People first domesticated horses some 6000 years ago in the Eurasian Steppe, near modern-day Ukraine and western Kazakhstan. As we put these animals to work over the next several thousand years, we selectively bred them to have desirable traits like speed, stamina, strength, intelligence, and trainability. People have tracked horse pedigrees for almost as long as we have kept them, but it wasn’t until the 1700s that detailed “studbooks” emerged in Europe to keep tabs on which horses fathered which foals and what characteristics the foals inherited.

The new study’s lead author, Barbara Wallner, an evolutionary biologist at the University of Veterinary Medicine in Vienna, paired these old, yet meticulously kept data with modern DNA sequencing techniques to investigate the origins of today’s horse breeds.


 

Whole mitochondrial genome sequencing of domestic horses reveals incorporation of extensive wild horse diversity during domestication

Sebastian Lippold Email author, Nicholas J Matzke, Monika Reissmann and Michael Hofreiter

BMC Evolutionary Biology 2011 11:328

©  Lippold et al; licensee BioMed Central Ltd. 2011

Received: 18 July 2011

Published: 14 November 2011

Abstract

Background

DNA target enrichment by micro-array capture combined with high throughput sequencing technologies provides the possibility to obtain large amounts of sequence data (e.g. whole mitochondrial DNA genomes) from multiple individuals at relatively low costs. Previously, whole mitochondrial genome data for domestic horses (Equus caballus) were limited to only a few specimens and only short parts of the mtDNA genome (especially the hypervariable region) were investigated for larger sample sets.

Results

In this study we investigated whole mitochondrial genomes of 59 domestic horses from 44 breeds and a single Przewalski horse (Equus przewalski) using a recently described multiplex micro-array capture approach. We found 473 variable positions within the domestic horses, 292 of which are parsimony-informative, providing a well resolved phylogenetic tree. Our divergence time estimate suggests that the mitochondrial genomes of modern horse breeds shared a common ancestor around 93,000 years ago and no later than 38,000 years ago.

A Bayesian skyline plot (BSP) reveals a significant population expansion beginning 6,000-8,000 years ago with an ongoing exponential growth until the present, similar to other domestic animal species. Our data further suggest that a large sample of wild horse diversity was incorporated into the domestic population; specifically, at least 46 of the mtDNA lineages observed in domestic horses (73%) already existed before the beginning of domestication about 5,000 years ago.

Science Shot: Horse Variety Predates Domestication

http://www.sciencemag.org/news/2011/11/scienceshot-horse-variety-predates-domestication
a new study, most of these traits existed long before we domesticated them. As researchers report online this month in BMC Evolutionary Biology, they analyzed the complete mitochondrial genome—the DNA found within cell's energy powerhouses—of 45 diverse horse breeds, looking for clues to the timing of horse domestication. They found that modern horses arose nearly 7000 years ago, a result that agrees with previous studies. The data also show that the ancestor of all domestic horses—which some scientists believed lived as long as 1 million years ago—roamed much more recently, between 38,000 and 93,000 years ago. In addition, more than 70% of today's horse lineages already existed before domestication, suggesting that a large number of wild founder mothers were used to build up the modern horse population.

By Karl Gruber

 

 

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