https://doi.org/10.52973/rcfcv-e33262

Received: 25/04/2023 Accepted: 22/06/2023 Published: 22/07/2023

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Revista Científica, FCV-LUZ / Vol. XXXIII, rcfcv-e33262, 1 – 7

ABSTRACT

This study aimed to determine the phylogenetic and bottleneck

analyses of Turkish Thoroughbred and Arabian horse populations. In

the study, genotyping was performed using a total of 17 microsatellite

markers in the samples taken from 959 Thoroughbred and 813 Arabian

horses. The average effective allele number in Arabian horses was

3.338 and the average number of alleles was 7.412 in Thorougbred

horses. Genetic distance and genetic identity between Thoroughbred

and Arabian breeds was 0.411 and 0.663, respectively. Also genetic

identity in each Arabian and Thoroughbred horse populations was

1.000. The FCA table showed that the two breeds were completely

separated from each other and were compatible. In conclusion; the

bottlenecks of Thoroughbred and Arabian horse populations were

in a normal L distribution and these horse breeds do not appear to

have succumbed to introgression. Therefore, they are not yet at risk

of extinction any time soon.

Key words: Arabian horse; bottleneck; microsatellite; phylogenetic

analysis; thoroughbred horse

RESUMEN



y de cuello de botella de las poblaciones de caballos árabes y de pura

sangre turcos. En el estudio, el genotipado se realizó utilizando un



caballos pura sangre y 813 caballos árabes. El número medio de alelos

efectivos en los caballos árabes fue de 3,338 y el número medio de







cada población de caballos árabes y pura sangre fue de 1.000. La tabla

FCA mostró que las dos razas estaban completamente separadas

entre sí y eran compatibles. En conclusión; los cuellos de botella

de las poblaciones de caballos pura sangre y árabes estaban en una

distribución L normal y estas razas de caballos no parecen haber



extinción en el corto plazo.

Palabras clave: Caballo árabe; cuello de botella; microsatellite;



Phylogenetic and bottleneck analysis of the Turkish Arabian and

Thoroughbred horse populations



sangre

Cevdet Yaralı

, Abdurrahman Köseman

* , Yusuf Özşensoy

, İbrahim Şeker

, Burhan Toprak

, Kemal Zengin

Veterinary Control Central Research Institute, Genetics Laboratory, Ankara, Türkiye.

Malatya Turgut Ozal University, Akcadag Vocational School, Department of Crop and Animal Production. Malatya, Türkiye.

Sivas Cumhuriyet University, Faculty of Veterinary Medicine, Department of Veterinary Genetics. Sivas, Türkiye.

Firat University, Faculty of Veterinary Medicine, Department of Zootechny. Elazig, Türkiye.

Yozgat Bozok University, Faculty of Veterinary Medicine, Department of Anatomy. Yozgat, Türkiye.

*Corresponding author: abdurrahman.koseman@ozal.edu.tr

Genetic Analysis of the Arabian and Thoroughbred Horses / Yaralı et al. ___________________________________________________________

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INTRODUCTION

Thoroughbred and Arabian horses constitute 4.2 and 15.1% of the

racing and riding population, respectively. These two breeds account

for 5.6 and 18.3% of parental lineage and 7.9 and 32.9% of founding

lineage, respectively. On the species scale, both breeds account for

altogether 26% of the founding origins [1].



2]. There are

3].

Genetic characterization studies have an important place in

the determination of inter and intra breeds genetic diversity and



to protect the purity of breeds and to identify breeding strategies

[4, 5]. Although the deoxyribonucleic acid (DNA) sequences lining

the repeat regions in microsatellites are the same in individuals of

a species, the number of repeats may vary between individuals and

even between homologous chromosomes of individuals. Therefore,

microsatellites are preferred in many molecular biology studies [5].

Microsatellite loci are more useful on the contrary classical genetic

markers to determine the genetic relationships of close populations

and to examine many polymorphic loci [6].

While the number of Thoroughbred horses running in the hippodromes

in Türkiye in 2021 was 3734 (55%), the number of Arabian horses running

was 3085 (45%). In the same year, the number of races organized

exclusively for Thoroughbreds was 3246 (54%), while the number of

races organized exclusively for Arabian horses was 2765 (46%) [7].

This research was aimed at studying phylogenetic and bottleneck

analysis of the Turkish Arabian and Thoroughbred horse populations

using microsatellite markers.

MATERIALS AND METHODS

Animals

All Arabian and Thoroughbred horses born in Turkiye or imported







This study’s research material consisted of 959 Thoroughbred



District Directorates of Agriculture and Forestry in Türkiye for their



Blood samples

The blood samples tested in the study were collected from 959

Thoroughbred and 813 Arabian horses, which were sent to Ankara







The blood samples used in the genetic analyzes were collected

by the official veterinarians using anticoagulant tripotassium

ethylenediaminetetraacetic acid (K

EDTA) tubes and delivered to the

laboratory under the cold chain. During the blood collection process,

the horses' name, chip number, age, gender, breeder and address

information and photographs were recorded in the database created









the Turkish Ministry of Agriculture and Forestry.

DNA Extraction

In the extraction of DNA from blood and some hair samples, both

manual and automatic isolation methods were performed. DNA isolation

from some of the blood samples was performed by Chelex 100 and











Microsatellite markers genotyping









to manufacturer protocols. Capillary electrophoresis of samples was



alleles were detected by using the GeneMapper software (Version 4.0).

Statistical data analysis

General population parameters including allele numbers (Na),



Genetic Distance and Identity were calculated using the GenAlEx6.501

program [8]. Factorial Correspondence Analysis (FCA) was performed

9

drawn, which revealed the relationship between each subject with





10]. Moreover, it was tested



program [11]. All these parameters were analyzed using the genotypic

12].



taken from the General Directorate of Food and Control, The Ministry of



approval was obtained from the Local Ethics Committee of Veterinary



RESULTS AND DISCUSSION



Allele numbers detected in Arabian and Thoroughbred horses were



(mean 8.53), the highest Na were determined in Arabian horses (13 alleles)







In the study, the mean effective number of alleles (Ne) was 3.338





horses. The mean Ne was smaller than the mean Na in Arabian horses



FIGURE 1. FCA chart of the Arabian and Thoroughbred horses (Yellow: Arabian

horses, Blue: Thoroughbred horses)

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Genetic distance and genetic identity between Thoroughbred

and Arabian breeds was found 0.411 and 0.663, respectively, in the

pairwise population matrix. Also genetic identity in each Arabian and



identity and genetic distance are opposite each other. A high genetic

identity creates a low genetic distance. Accordingly, it can be said that

there is a moderate genetic identity and genetic distance between the

Arabian and Thoroughbred horse populations (between breeds). A high

genetic identity creates a low genetic distance. Accordingly, it can be said

that there is a moderate genetic identity and genetic distance between



genetic distance in Arabian and also Thoroughbred horses themselves.

TABLE I

Sample size (N), number of alleles (Na) and number of effective alleles

(Ne) over all loci for Arabian and Thoroughbred horse populations

Arabian horses Thoroughbred horses Total

Locus N Na Ne N Na Ne Na

AHT4 813 9 3.615 959 5 3.475 9

AHT5 813 7 3.063 959 7 2.905 9

ASB2 812 13 3.176 958 11 6.456 14

ASB17 813 8 3.220 957 7 4.063 10

ASB23 813 6 3.753 957 8 4.353 9

CA425 813 6 3.908 959 8 2.197 8

HMS1 813 11 2.718 959 5 2.810 11

HMS2 813 7 2.630 959 6 1.836 9

HMS3 813 8 4.790 673 6 3.104 8

HMS6 813 6 3.083 959 5 2.583 6

HMS7 813 6 3.654 958 6 4.761 6

HTG4 813 5 3.323 959 5 2.144 5

HTG6 813 4 2.161 959 6 2.664 7

HTG7 813 4 1.477 959 5 2.712 6

HTG10 808 8 4.280 956 8 5.358 9

LEX3 428 8 4.107 555 7 4.713 8

VHL20 813 10 3.793 959 6 3.939 11

Mean 790 7.412 3.338 917.882 6.529 3.534 8.53

Almarzook et al. [13] detected a total of 251 polymorphic Na in



and also overall mean of Ne was 4.141. Machmoum et al. [14] concluded

that the mean Na per locus was 6.52, 6.35, and 7 in the Desert breed,

et al.

[15] reported that Na had 118 alleles (mean 7.375) per locus ranging





The Na and Ne are one of the main indicators of genetic diversity,

also Ne indicates a higher probability of extinction. Even if the values





microsatellite panel; all of the markers in the current study have a

credible polymorphism to assess genetic variation in Arabian and

Thoroughbred horse populations.

Phylogenetic analysis

Genetic distance and genetic identity matrix in Arabian and

16], and

the genetic relationship of the two breeds to each other was shown



Thorougbred bred horses was drawn separetely (FIG 2 and FIG 3).

Grouping values that ensured reliability with the bootstrap test (1,000



Thoroughbred horse populations are divided into numerous groups

by phylogenetic trees.

TABLE II

Genetic distance and genetic identity matrix in

Arabian and Thoroughbred horse populations

Breed Arabian horses Thoroughbred horses

Genetic

distance

Genetic

identity

Genetic

distance

Genetic

identity

Arabian horses 0.000 1.000 – –

Thoroughbred horses 0.411 0.663 0.000 1.000

In the FCA for Arabian and Thoroughbred horses observed that one

group was concentrated in the middle, and the others were located



the FCA chart the two breeds were completely separated from each

other and compatible. According to the results, these horse breeds

or populations seem not submitted to introgression.

Mahrous et al. [17] reported that the highest genetic distance was

found to be 0.4405 in Thoroughbred and Native breeds, and the lowest

genetic distance was found to be 0.2586 in Native and Arabian horses.

The values determined in our research are lower than these values.

et al. [18] determined that



et al. [13]

reported that the three breeds were distributed all over the adjacent



FIGURE 2. (A-H) NJT tree generated with STRs to show bootstrap values of Arabian horse genotype (n=813)

C D

E F G H

Genetic Analysis of the Arabian and Thoroughbred Horses / Yaralı et al. ___________________________________________________________

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FIGURE 3. (A-H) NJT tree generated with STRs to show bootstrap values of Thoroughbred horse genotype (n=959)

E F G H

C D

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FIGURE 4. Bottleneck chart of the Arabian horse population

FIGURE 5. Bottleneck chart of the Thoroughbred horse population

Genetic Analysis of the Arabian and Thoroughbred Horses / Yaralı et al. ___________________________________________________________

6 of 7



using 18 microsatellites, it was determined that there was no danger

of inbreeding, and Thoroughbreds were the largest contributor to the

22

on sport horses it was concluded that if the population was under

bottleneck effect, the genetic variation reduction was observed in the

23]. Moreover, Koseman et al. [24] stated

that the bottleneck assessment of the colored horse population was at a

normal L distribution and there was no risk of extinction in the population.



in the literature, there is no bottleneck risk yet in the Arabian and

Thoroughbred populations we have studied

CONCLUSION

The results provided decent data about the sophisticated genetic



Moreover, it underlined the availability and great utilility of the Arabian

and Thoroughbred horse gene stock at least at Türkiye scale. For this

reason the results might give disclosure and suggestion concerning

Arabian and Thoroughbred horse breeds upkeep. In this context, the



○

Arabian and Thoroughbred horses have an important genetic

potential in Türkiye.

○

There is very high genetic variability in Arabian and

Thoroughbred horse populations.

○



tree are divided into many groups within themselves.

○

Neither horse breed population is at risk of extinction any

time soon.

ACKNOWLEDGMENTS



and Forestry for its cooperation in providing data.





BIBLIOGRAPHIC REFERENCES

 





 





 

diversity, pedigree relatedness and the contributions of founder



 



 





haplogroups (FIG 2 and FIG 3).

Cosgrove et al. [19] stated that there was a high degree of genetic

variation and complex ancestry in Arabian horses from the Middle

East region. Moreover, in this work it was concluded that powerful





Arabian breed to the Thoroughbred horses.

Limiting inbreeding in the horse population will reduce the effect

of undesirable hereditary traits.

Bottleneck analysis

The analyses of bottleneck risk in Arabian and Thoroughbred



Thoroughbred horse populations was at a normal L distribution.

Duru [20] also reported that the Arabian horse breed might not be

at risk. In a study that analyzed the relationship between inbreeding

and racing performance, it was found that selective breeding did not

effectively alleviate the genetic load of the Australian Thoroughbred

population [21].

______________________________________________________________________Revista Cientifica, FCV-LUZ / Vol. XXXIII, rcfcv-e33262, 1 – 7

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[6] Takezaki N, Nei M. Genetic distances and reconstruction of

phylogenetic trees from microsatellite DNA. Genet. 1996;



 

.

 





 





.

[10] Langella



.

 

for detecting recent reductions in the effective population size



 



 

GA. Genetic diversity of Arabian horses using microsatellite



 

M. Genetic diversity and population structure of Arabian horse





 





 



 





 





 











 

structure, inbreeding and genetic variability. Anim. 2017;



 





 





 



horses participating in competitions for young horses. Front.



 





