Researchers have found relatively high maternal genetic diversity in Poland’s primitive Konik horse breed, despite limited numbers.
The study team says the diversity is on a similar scale to that seen in Arabian horses, and was higher than levels observed in some European and Asiatic native breeds
The Konik, also known as the Polish Primitive Horse, is a breed created at the beginning of 20th century using primitive horses from eastern Poland.
The founders of the breed were recruited from local people who kept the small, Tarpan-looking horses mainly because of their low food requirements and good adaptation to the difficult environmental conditions.
The start of organized Konik breeding was in 1923 when the first individuals were placed in the oldest Polish national horse stud in Janów Podlaski.
Before World War 2, Koniks were kept in several breeding centers in the eastern Poland in order to keep the horses in a presumed natural habitat.
Unfortunately, from the population of over 140 Koniks that remained in Polish studs at the beginning of German occupation in 1939, only about one-third survived the war.
From that time, the breed has been developing strenuously and in 1962 the first official studbook was published, describing 34 maternal and six paternal lines. Over 20 years later, an additional line was delineated.
Unfortunately, due to improper supervision of breeding before the Konik conservation program was established, 19 of the 35 maternal lines have been lost and are considered extinct. Furthermore, some of the 16 maternal lines are now endangered.
Since 1985, the Polish Primitive Horse studbook has been closed and no outside blood is recorded.
Since 2000 the breed has been managed within a conservation program supervised by the National Research Institute of Animal Production in Balice, Poland.
Jakub Cieslak and his colleagues, writing in the online journal PeerJ, said the main features that distinguished the Konik breed from others were their limited food needs, good health and good reproductive ability. Their superior adaptation to their natural habitat, together with their characteristic appearance of a primitive horse (including body shape and coat color) gave rise to the view that the breed had inherited a significant number of traits from the wild Tarpan.
The Konik breed is therefore considered a valuable resource of domestic horse biodiversity.
According to the Polish Horse Breeders Association, the current number of the breeding Polish Primitive horses exceeds 1600, comprising 1450 broodmares and 160 stallions.
The researchers said the numbers clearly show that the population of the breed had increased rapidly over the last two decades from a very limited number of founders.
“It is obvious,” they wrote, “that the genetic diversity parameters of this population should be constantly monitored.”
This, they said, was confirmed by a recent study showing an increase of the inbreeding coefficient within the breed.
The study team set out to characterize the genetic diversity in Konik maternal lines based on mitochondrial DNA. In all, DNA samples from 173 individuals were tested from mares representing the 16 existing maternal lines.
Altogether, 19 mitochondrial DNA haplotypes – a haplotype is a set of genetic determinants located on a single chromosome – were detected in the Konik population.
Five haplotypes were considered to be novel while the remaining 14 showed a good match with sequences deposited in the GenBank genetic sequence database, represented by both modern and primitive horse breeds.
Further genetic similarities were seen between the Konik and other indigenous horse breeds derived from various geographical regions, such as the Iberian Peninsula, Eastern Europe and Siberia. This finding supported the hypothesis that, within the Konik breed, many ancestral haplotypes found all over the world were still present.
Only in the case of five maternal lines was the segregation of one specific mitochondrial DNA haplotype observed. The 11 remaining maternal lines showed a higher degree of variability.
The researchers concluded there was relatively high maternal genetic diversity in the the breed.
“However, only some traditionally distinguished maternal lines can be treated as genetically pure. The rest show evidence of numerous mistakes recorded in the official Polish Primitive Horse pedigrees.
“This study,” they continued, “has proved the importance of maternal genetic diversity monitoring based upon the application of molecular mitochondrial DNA markers and can be useful for proper management of the Polish Primitive Horse conservation program in the future.”
They concluded: “The detected significant discrepancies between pedigree and molecular data are convincing evidence that the Polish Primitive Horse conservation program, which is concentrated mainly on the protection and development of the 16 existing maternal lines, needs an extensive revision (even the re-division of the … maternal lines using the mitochondrial-DNA derived data should be considered).
“Otherwise, the distinguishing of Polish Primitive Horse dam lines will continue based upon the breeders tradition only, not supported by the valuable pedigree data.”
The research team comprised Cieslak, Lukasz Wodas, Alicja Borowska, and Mariusz Mackowski, all from the Poznan University of Life Sciences in Poland; and Gus Cothran and Anas Khanshour, from Texas A&M University.
Cieslak J, Wodas L, Borowska A, Cothran EG, Khanshour AM, Mackowski M. (2017) Characterization of the Polish Primitive Horse (Konik) maternal lines using mitochondrial D-loop sequence variation. PeerJ 5:e3714 https://doi.org/10.7717/peerj.3714