Limited genetic diversity in stallions revealed in study
Austrian researchers bring revealed the relationships betwixt European Equus caballus breeds inward a written report which highlights the express sort inward the manly individual genetic line.
They written report reveals the unopen relationships with modern stallions, due mainly inward business office to breeding practices.
Until recently, in that place has been express genetic information available to investigate the paternal lines of the domestic horse.
This gap has been filled past times Barbara Wallner too her colleagues at the University of Veterinary Medicine inward Vienna, who bring presented information on the genetic variability inward the horse’s Y chromosome. In doing too hence they bring been able to exhibit how various breeds of the modern Equus caballus are interrelated.
The results bring simply been published inward the online journal, PLoS ONE.
In mammals, an individual’s gender activity is determined past times the chromosomes it inherits from its parents. Two X chromosomes Pb to a female, whereas 1 X too 1 Y Pb to a male. Y chromosomes are exclusively passed from fathers to sons, too hence each Y chromosome represents the manly individual genealogy of the beast inward question.
In contrast, mitochondria are passed on past times mothers to all their offspring. This agency that an analysis of the genetic fabric or deoxyribonucleic acid of mitochondria tin give information on the woman individual ancestry.
For the modern horse, it is good known that mitochondrial deoxyribonucleic acid is extremely various too this has been interpreted to hateful that many ancestral woman individual horses bring passed their deoxyribonucleic acid on to modern Equus caballus breeds.
Until recently, though, essentially no sequence sort had been detected on the Y chromosome of the domestic horse.
Not exclusively does the lack of sequence markers on the Y chromosome arrive impossible to delineate manly individual lineages with confidence, it besides represents a scientific paradox. How tin a species with too hence many woman individual lines bring too hence few manly individual lines?
Barbara Wallner too her colleagues at the university’s Institute of Animal Breeding too Genetics initially selected 17 horses from a arrive at of European breeds for the study.
She pooled their deoxyribonucleic acid too used modern sequencing technology scientific discipline to examine the seat of sort on a 200-kilobyte part of the Y chromosome she had previously sequenced.
The Y chromosomes were found to live highly like – exclusively 5 positions turned out to live variable.
“The results confirmed what nosotros had previously suspected – that the Y chromosomes of modern breeds of Equus caballus exhibit far less variability than those of other domestic animals,” Wallner said.
The 5 variable positions, or polymorphisms, were silent sufficient to enable the researchers to derive a type of “family tree” for the various breeds of modern Equus caballus they investigated.
An seek out of over 600 stallions from 58 largely European breeds showed that the animals could live grouped into 6 basic lines or haplotypes.
The ancestral haplotype is distributed across close all breeds too geographical regions.
A minute haplotype besides occurs at high frequencies across a broad arrive at of breeds, although non inward northern European breeds or inward horses from the Iberian Peninsula.
A tertiary haplotype is introduce inward close all English linguistic communication thoroughbreds too inward many warmblooded breeds.
The finally 3 haplotypes are exclusively found inward local northern European breeds – 1 inward Icelandic horses, 1 inward Norwegian Fjord horses too 1 inward Shetland ponies.
The pedigree of horses is rattling tightly controlled, with studbooks inward many cases going equally far dorsum equally the 18th century.
Combining the results of the genetic analysis with pedigree information enabled the scientists to delineate the paternal roots of many of the electrical current manly individual lines.
“The results were intriguing,” Wallner said. “For example, inward the way the distribution of 1 haplotype reflects the widespread make of stallions from the Middle East to Central too Western Europe inward the past times 200 years.
“Another haplotype results from a mutation that occurred inward the famous English linguistic communication thoroughbred stallion Eclipse or inward his boy or grandson.
“It is amazing to come across how much influence this work has had on modern sport horses: Almost all English linguistic communication thoroughbreds too nearly one-half the modern sport Equus caballus breeds comport the Eclipse haplotype.”
The Austrian scientists bring confirmed the depression sort of the Equus caballus Y chromosome, which contrasts sharply with arrive at of (female) mitochondrial deoxyribonucleic acid haplotypes observed inward modern horses.
The departure is presumably due to the rigid variation inward manly individual reproductive success. Wild horses bring a polygynous breeding pattern, piece the intensive breeding practices inward domestic horses hateful that unmarried stallions tin effectively exceed on their deoxyribonucleic acid to entire generations.
The senior writer on the paper, Gottfried Brem, said: “Most modern breeds were established inward the finally 2 centuries, during which fourth dimension the Equus caballus has undergone a transition from working too military machine piece of work towards leisure too sports.
“This has largely been achieved through the piece of work inward breeding of a few selected males.
“The restricted genetic sort of the modern Equus caballus Y chromosome is a reflection of what has survived the species’ dynamic history.”
The paper, “Identification of genetic variation on the Equus caballus Y chromosome too the tracing of manly individual founder lineages inward modern breeds”, past times Wallner, Brem, Claus Vogl, Priyank Shukla, Joerg Burgstaller too Thomas Druml, has simply been published online inward the open-access journal, PLoS ONE.
The published written report tin live accessed at http://dx.plos.org/10.1371/journal.pone.0060015
Breeds of analysed males are listed on the bottom too the haplotypes of their ancestors are reconstructed (HT2-yellow, HT3-red, unknown-grey). Selected famous stallions are shown past times name; dotted lines connect relatives where at to the lowest degree 1 ancestor is omitted. No descendants from “Pot8os” too “Waxy” were available apart from “Whalebone, 1807”. The mutation leading to HT3 must bring occurred either inward the germline of stallion “Eclipse” [54] or inward his boy “Pot8os” or inward his grandson “Waxy” too rose to rattling high frequency inward the English linguistic communication Thoroughbred too many sport Equus caballus breeds through the progeny of the stallion “Whalebone”.
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