High-Level Gene Flow Restricts Genetic Differentiation in Dairy Cattle Populations in Thailand: Insights from Large-Scale Mt D-Loop Sequencing.

Nattakan Ariyaraphong,Worapong Singchat,Thitipong Panthum,Danai Jattawa,Kornsorn Srikulnath,Skorn Koonawootrittriron,Nararat Laopichienpong,Syed Farhan Ahmad,Prateep Duengkae,Narongrit Muangmai,Thanathip Suwanasopee

doi:10.3390/ani11061680

Abstract

Simple SummaryDomestication and artificial selection lead to the development of genetically divergent cattle breeds or hybrids that exhibit specific patterns of genetic diversity and population structure. Development of mitochondrial markers has allowed investigation of cattle diversity worldwide; however, an extensive study on the population-level genetic diversity and demography of dairy cattle in Thailand is still needed. Reduction in the genetic diversity of livestock also decreases the species resilience and adaptability to local environmental conditions and disease outbreaks, thus leading us to hypothesize that Thai dairy cattle populations are approaching a status of low genetic variability. In the present study, the genetic diversity and structure of Thai dairy cattle populations were investigated, both within and between populations, for 179 individuals from nine provinces of Thailand. Mitochondrial D-loop sequence data were collected and analyzed. To minimize the degree of relationship among individuals, cattle were randomly selected based on details interviewed with the owners. The results will facilitate an improved understanding of the fundamental elements involved in breeding strategies and promote sustainable livestock utilization.Domestication and artificial selection lead to the development of genetically divergent cattle breeds or hybrids that exhibit specific patterns of genetic diversity and population structure. Recently developed mitochondrial markers have allowed investigation of cattle diversity worldwide; however, an extensive study on the population-level genetic diversity and demography of dairy cattle in Thailand is still needed. Mitochondrial D-loop sequences were obtained from 179 individuals (hybrids of Bos taurus and B. indicus) sampled from nine different provinces. Fifty-one haplotypes, of which most were classified in haplogroup “I”, were found across all nine populations. All sampled populations showed severely reduced degrees of genetic differentiation, and low nucleotide diversity was observed in populations from central Thailand. Populations that originated from adjacent geographical areas tended to show high gene flow, as revealed by patterns of weak network structuring. Mismatch distribution analysis was suggestive of a stable population, with the recent occurrence of a slight expansion event. The results provide insights into the origins and the genetic relationships among local Thai cattle breeds and will be useful for guiding management of cattle breeding in Thailand.

Highlights

Cattle are among the most economically important domesticated animals in the world.The majority are humpless taurine (Bos taurus) [1] and zebu (B. indicus) [1] that likely originated from the aurochs (B. primigenius) through a domestication event some 8000–10,000 years ago, and spread globally by means of human trade and migration [2,3].Bos taurus produces high quality and yield of milk, especially the Holstein and European cattle breeds
Intensive artificial selection has resulted in highly productive global dairy cattle breeds that have replaced local breeds, leading to a loss of diversity
Thai dairy cattle derived from a crossbreed between B. taurus and B. indicus have adapted over 60 years to the harsh native environment, accrued resistance to tropical diseases and external parasites, and obtained sustenance on lowquality roughage and grasses following traditional methods of animal husbandry [57]

Summary

Introduction

The majority are humpless taurine (Bos taurus) [1] and zebu (B. indicus) [1] that likely originated from the aurochs (B. primigenius) through a domestication event some 8000–. Bos taurus produces high quality and yield of milk, especially the Holstein and European cattle breeds. B. indicus has lower milk production but is more tolerant to high temperature and humidity [4]. Cattle in Thailand were used primarily for draft and meat production [8], but in the 1950s cooperation between the Thai government and the United Nations led to the initiation of a milk program for schools to improve the nutritional status of local communities by providing powdered and fresh milk [9]

Methods

Results

Discussion

Conclusion