Gene conservation of six Hungarian local chicken breeds maintained in small populations over time

Abstract

Investigation into the genetic diversity of certain endangered native breeds of domestic animals has been in common practice for several decades. The primary objective of these investigations has been to reveal the exceptional genetic value of such breeds, both for their conservation and also to gain insight into their current genetic status, as they have been undergoing a progressive decrease in population size and general diversity; this has been compounded by the general lack of an optimal breeding scheme. In this study, we have investigated changes in the genetic diversity of six Hungarian local chicken breeds based on 29 microsatellite loci over a period of 15 years. In terms of the basic diversity measures, populations sampled in 2017 generally exhibited a lower heterozygosity and mean number of alleles and thus, experienced a higher degree of inbreeding. Although the effective population size increased, the estimates of populations sampled over different periods indicated comparatively low values, suggesting overall lower genetic variance. Pairwise F ST estimates were higher in the populations sampled in 2017, showing a larger genetic distance between them. Considerable differences exist between the populations of the same breeds, which can most likely be attributed to genetic drift. STRUCTURE results have shown a clear separation between the Hungarian populations, which is in agreement with the principal coordinate analysis. The most likely clustering was found at K = 6, classifying the populations of the same breed as one group. No considerable allele loss was found in the Hungarian indigenous chicken breeds after 15 years of conservation. In general terms, after 15 years, the level of inbreeding within the populations was, in fact, higher, although this could be effectively reduced through the use of an improved mating system. Consequently, the breed management applied in the case of Hungarian local chicken breeds was found to be effective at adequately conserving their genetic variability.

Monitoring changes in the genetic structure of Brown Tsaiya duck selected for feeding efficiency by microsatellite markers

“…The results are similar to those of the Hungarian study; the variance among populations increased from 23% to 25%, and the variance among individuals increased from 1% to 6% between 2002 and 2017 [11]. Therefore, the change in AMOVA results may also have been caused by genetic drift or selection.…”

“…However, the Ne in both line were higher than Hungarian chicken breed study using a temporal method (4.4-12.7) [11]. However, it is similar to Speckled Hungarian in the same study and a study on indigenous Chinese chickens estimated by genome-wide single nucleotide polymorphisms (SNPs) using the LD method [43].…”

“…And the pairwise FST between lines from 0.0307 (C2 and S2) increased to 0.1271 (C8 and S8), the result is similar to Hungarian study. The pairwise FST between breeds ranged from 0.15 to 0.28 in 2002 and slightly increased to 0.21 to 0.30 after 15 years, the differentiation increased, and genetic similarity between breeds decreased over time [11].…”

“…However, although a few studies have investigated the genetic polymorphisms of duck breeds for conservation, most studies investigated multiple populations at a single time point; no crossgenerational genetic monitoring study on ducks has been conducted. On the other hand, some cross-generation monitoring studies on chickens, and they pointed out that the smaller the population is, the more often their allele frequencies change, and monitoring changes in genetic polymorphisms over time is crucial for poultry conservation and breeding programs [11,12].…”

Comparative Analysis of Molecular RFLP and SNP Markers in Assessing and Understanding the Genetic Diversity of Various Chicken Breeds

“…According to the MLDF data, in ZS, RW, SL, Pm, and OMF was slightly lower, as a result of the effort to restore their genetic diversity, including measures such as individual selection and purchase of breeding eggs from other collections from 2007 to 2017. The importance of monitoring genetic variability for the timely adjustment of breeding priorities in small populations has also been emphasized by other authors [ 65 , 66 ].…”