Genetic diversity and matrilineal genetic signature of native Ethiopian donkeys (Equus asinus) inferred from mitochondrial DNA sequence polymorphism

Mitochondrial DNA diversity and maternal origins of Pakistani donkey

Abstract Domestic donkey plays a key role as a draft animal in rural economy of Pakistan where its population is increasing every year. The complete mtDNA control region of forty randomly sampled donkeys was PCR- amplified and sequenced bi-directionally using specific primers. Distinct mtDNA haplotypes obtained in the current study (KY446001−KY446011) were subjected to haplotype (h) and nucleotide diversity (π) measures using DnaS as well as to phylogenetic, Network, and AMOVA analyses. There were a total 27 polymorphic sites present within 11 unique mtDNA haplotypes from the studied 40 animals from different regions. Neighbor-joining network and median-joining network both illustrated the splitting of all these haplotypes into two well-defined Nubian and Somali lineages, confirming African maternal origin of Pakistani domestic donkey. Diversity parameters h (0.967± 0.037) and π (0.02917± 0.00307) were found to reveal high levels of genetic diversity in Pakistani donkeys. AMOVA demonstrated only 1% of genetic differences between two mtDNA maternal lineages, pointing to lack of population substructure in Pakistani donkeys as is the case with worldwide domestic donkey population. Pakistani donkeys have African maternal origin and high levels of mtDNA diversity. High genetic diversity may be due to non-selective breeding and heteroplasmy. We herein provide the first report on mtDNA diversity of control region in Pakistani domestic donkey.

Exploring Genetic Markers: Mitochondrial DNA and Genomic Screening for Biodiversity and Production Traits in Donkeys

Donkeys (Equus asinus) play a pivotal role as essential livestock in arid and semi-arid regions, serving various purposes such as transportation, agriculture, and milk production. Despite their significance, donkey breeding has often been overlooked in comparison to other livestock species, resulting in limited genetic improvement programs. Preserving donkey genetic resources within each country necessitates the establishment of breed conservation programs, focusing on managing genetic diversity among populations. In recent years, significant strides have been made in sequencing and analyzing complete mitochondrial DNA (mtDNA) molecules in donkeys. Notably, numerous studies have honed in on the mitochondrial D-loop region, renowned for its remarkable variability and higher substitution rate within the mtDNA genome, rendering it an effective genetic marker for assessing genetic diversity in donkeys. Furthermore, genetic markers at the RNA/DNA level have emerged as indispensable tools for enhancing production and reproduction traits in donkeys. Traditional animal breeding approaches based solely on phenotypic traits, such as milk yields, weight, and height, are influenced by both genetic and environmental factors. To overcome these challenges, genetic markers, such as polymorphisms, InDel, or entire gene sequences associated with desirable traits in animals, have achieved widespread usage in animal breeding practices. These markers have proven increasingly valuable for facilitating the selection of productive and reproductive traits in donkeys. This comprehensive review examines the cutting-edge research on mitochondrial DNA as a tool for assessing donkey biodiversity. Additionally, it highlights the role of genetic markers at the DNA/RNA level, enabling the informed selection of optimal production and reproductive traits in donkeys, thereby driving advancements in donkey genetic conservation and breeding programs.

Phenotypic characterization of donkey population in South Omo Zone, Southern Ethiopia

The study conducted in South Omo Zone, Southern Ethiopia with the aim of investigation within population diversification and characterization morphologically that helps to fill the gap of molecular characterization on this population. The data was collected from 500 adult donkeys from both sexes. Quantitative data was subjected to SAS GLM procedures by fitting districts and sex as the main effects. Qualitative data was subjected to a chi-square test with the district as the main effect. Color graph of donkey was done using Microsoft Excel, 2010. For both qualitative and quantitative data, the significance test was conducted at 5% of the level of error, and Tukey multiple range tests were used to separate the significance levels for the two types of data. CANDISC was used to calculate Mahalanobis distances, DISCRIM was used to cluster observations into predetermined groups, and STEPDISC was used to determine the quantitative characteristics that better differentiate populations. Roan coat color cover highest number compare with other coat color of donkey population. Quantitative traits of donkey has variation (P < 0.05) both in study areas and sex of donkeys. Overtly, except height at wither and height at the back Hammer donkey has mostly better metric value than the rest districts of the study areas. Moreover, CANDISC show variation on Hammer and Dasenech districts of donkey population. Furthermore, the longest (6.32) Mahalanobis distance observed in between Hammer and Dasenech donkey population. The Hammer and Dasenech donkey population is where the study fills in population variation the most. This can be because to management or genetics. Therefore, additional research might be required. Furthermore, morphometric measures show that donkey sex is similar, with the exception of heart girth circumference. This can be the result of poor selection, where superior male donkeys are sold for a higher price. Therefore, sound breeding programs should be used to reverse it.

Mitogenomic phylogeny reveals the predominance of the Nubian lineage of African wild ass in Indian donkeys

To contribute to the knowledge of maternal genetic diversity in domestic donkeys, this study investigated the mitochondrial DNA variations and analyzed the genetic structure in Indian donkeys based on 31 mitogenome sequences representing four breeds/populations (Agra, Halari, Kachchhi and Spiti). A total of 27 haplotypes with a haplotype diversity value of 0.989 were evident in the donkey genetic resources of India. The genetic differentiation between the investigated populations was evaluated using population pairwise F_ST values, which showed maximum differentiation between Kachchhi and Halari donkeys. The Neighbor-Joining (NJ) tree based on the whole mitogenome sequence and the Median-Joining (MJ) network for partial D-loop fragment showed clear demarcation of Indian donkeys into Nubian and Somali clades, substantiating African maternal origin of Indian domestic donkeys. The topology of the MJ network excluded the Asian wild asses as the possible progenitors of Indian donkeys. Halari and Agra donkeys showed conformity exclusively to the Nubian lineage of the African wild asses. However, representation of both the Nubian and Somali lineages was observed in Kachchhi and Spiti donkeys. Comprehensive analysis carried out by retrieving D-loop sequences from different countries representing Asia, Africa, Europe and South America revealed existence of shared haplotypes across geographically isolated regions of the globe. This observation is indicative of utility of donkeys as pack animals across inter-continental trading routes during development of human civilizations. Our results represent a valuable contribution to maternal genetic diversity of Indian donkeys and provide insights into the worldwide spread of the species following initial domestication in Africa.

Maternal Phylogenetic Relationships and Genetic Variation among Rare, Phenotypically Similar Donkey Breeds

The mitochondrial DNA (mtDNA) D-loop of endangered and critically endangered breeds has been studied to identify maternal lineages, characterize genetic inheritance, reconstruct phylogenetic relations among breeds, and develop biodiversity conservation and breeding programs. The aim of the study was to determine the variability remaining and the phylogenetic relationship of Martina Franca (MF, with total population of 160 females and 36 males), Ragusano (RG, 344 females and 30 males), Pantesco (PT, 47 females and 15 males), and Catalonian (CT) donkeys by collecting genetic data from maternal lineages. Genetic material was collected from saliva, and a 350 bp fragment of D-loop mtDNA was amplified and sequenced. Sequences were aligned and evaluated using standard bioinformatics software. A total of 56 haplotypes including 33 polymorphic sites were found in 77 samples (27 MF, 22 RG, 8 PT, 19 CT, 1 crossbred). The breed nucleotide diversity value (π) for all the breeds was 0.128 (MF: 0.162, RG: 0.132, PT: 0.025, CT: 0.038). Principal components analysis grouped most of the haplogroups into two different clusters, I (including all haplotypes from PT and CT, together with haplotypes from MF and RG) and II (including haplotypes from MF and RG only). In conclusion, we found that the primeval haplotypes, haplogroup variability, and a large number of maternal lineages were preserved in MF and RG; thus, these breeds play putative pivotal roles in the phyletic relationships of donkey breeds. Maternal inheritance is indispensable genetic information required to evaluate inheritance, variability, and breeding programs.

Genomics and the Evolutionary History of Equids

The equid family contains only one single extant genus, Equus, including seven living species grouped into horses on the one hand and zebras and asses on the other. In contrast, the equine fossil record shows that an extraordinarily richer diversity existed in the past and provides multiple examples of a highly dynamic evolution punctuated by several waves of explosive radiations and extinctions, cross-continental migrations, and local adaptations. In recent years, genomic technologies have provided new analytical solutions that have enhanced our understanding of equine evolution, including the species radiation within Equus; the extinction dynamics of several lineages; and the domestication history of two individual species, the horse and the donkey. Here, we provide an overview of these recent developments and suggest areas for further research.

Phylogenetic Relationships of Turkish Indigenous Donkey Populations Determined by Mitochondrial DNA D-loop Region

Simple Summary

This paper represents the first fundamental report of mtDNA diversity in Turkish indigenous donkey breeds and presents findings for the origin and genetic characterization of donkey populations dispersed in seven geographical regions in Turkey, and thus reveals insights into their genetic history. The median-joining network and phylogenetic tree exhibit two different maternal lineages of the 16 Turkish indigenous donkey populations.

Abstract

In this study, to analyze the mtDNA D-loop region and the origin of the maternal lineages of 16 different donkey populations, and to assess the domestication of Turkish indigenous donkeys in seven geographical regions, we investigated the DNA sequences of the D-loop region of 315 indigenous donkeys from Turkey. A total of 54 haplotypes, resulting from 35 polymorphic regions (27 parsimoniously informative and 6 singleton sites), were defined. Twenty-eight of these haplotypes are unique (51.85%), and 26 are shared among different Turkish indigenous donkey populations. The most frequent haplotype was Hap 1 (45.71%), followed by two haplotypes (Hap 4, 15.55% and Hap 7, 5.39%). The breed genetic diversity, evaluated by the haplotype diversity (H_D) and nucleotide diversity (π_D), for the Turkish donkey populations ranged from 0.533 ± 0.180 (Tekirdağ–Malkara, MAL) to 0.933 ± 0.122 (Aydin, AYD), and from 0.01196 ± 0.0026 (Antalya, ANT) to 0.02101 ± 0.0041 (Aydin, AYD), respectively. We observed moderate-to-high levels of haplotype diversity and moderate nucleotide diversity, indicating plentiful genetic diversity in all of the Turkish indigenous donkey populations. Phylogenetic analysis (NJT) and median-joining network analysis established that all haplotypes were distinctly grouped into two major haplogroups. The results of AMOVA analyses, based on geographic structuring of Turkish native donkey populations, highlighted that the majority of the observed variance is due to differences among samples within populations. The observed differences between groups were found to be statistically significant. Comparison among Turkish indigenous donkey mtDNA D-loop regions and haplotypes, and different countries’ donkey breeds and wild asses, identified two clades and which is named Somali (Clade IV) and Nubian (Clade V) lineages. The results can be used to understand the origin of Turkish donkey populations clearly, and to resolve the phylogenetic relationship among all of the different regions.

Variability analyses of the maternal lineage of horses and donkeys

Equid breeds originating from the Iberian Peninsula and North Africa are believed to have genetically contributed to the formation of breeds and ecotypes from Brazil. The country has numerous breeds and ecotypes of horses and donkeys but there are no extensive studies on maternal genetic diversity and their origins. This study reports the results of the first genetic analysis of all horse and donkey breeds/ecotypes from Brazil based on sequences of the mitochondrial DNA control region (D-loop) whose main objective was to characterize the genetic variation in these animals. These analyses will contribute to the understanding of the current population structure and diversity of breeds/ecotypes of horses and donkeys raised in the Brazil. We analyzed 310 D-loop sequences representing 41 breeds/ecotypes of Equus caballus and Equus asinus, including 14 native horse breeds/ecotypes, 3 native donkey breeds/ecotypes and 24 cosmopolite horse breeds. The results revealed that the breeds are well structured genetically and that they comprise different groups. A total of 80 and 14 haplotypes were identified for horses and donkeys, respectively. Most of the horse mtDNA haplotypes were shared by many breeds, whereas donkey mtDNA haplotypes seemed to be more group-especif. Some groups presented a low intrabreed distance and/or a low haplotype/nucleotide diversity such as Lavradeiro, Crioulo, Piquira and Percheron horses and Brazilian donkey. Thus, specific actions must be designed for each population. The different levels of genetic diversity provided important information for conservation resource management of adapted groups as well as for mating orientation of breed associations. Some autochthonous ecotypes require attention because of their low genetic variability.

Banat donkey, a neglected donkey breed from the central Balkans (Serbia)

The dominant donkey breed in the Balkans is the mid-sized Balkan donkey with a grey to chocolate coat color. Local breeders from Serbia, however, still maintain a few larger individuals of a lighter coat color, named Banat donkey, and speculate that they are descendants of a Spanish donkey heard that had been transferred to the Banat region by the Hapsburg Queen Maria Theresa in the XVIII century for a specific purpose, to work in local vineyards. We have previously found a unique nuclear gene-pool and a prevalence of mitochondrial Clade 2 haplotypes in several such animals. In this study, we: (i) perform a comparative analysis of 18 morphological traits of the Banat donkey (seven individuals), Balkan donkey (53 individuals from two sub-populations of this breed) and the potential hybrids (eight individuals), and demonstrate the morphological distinctiveness of the Banat donkey, highlighting the diagnostic traits for distinguishing the breed: hip height, croup width, body length and chest depth; (ii) re-analyse published nuclear microsatellite data for these groups, and reveal that, although severely depopulated, the genetically distinct Banat donkey is not severely affected by the loss of genetic diversity and inbreeding; (iii) demonstrate that previously published Banat donkey mitochondrial haplotypes, analyzed genealogically together with those reported in ancient and modern individuals from Spain, Italy, Turkey, Cyprus and Africa, are shared with three Spanish breeds and individuals belonging to Amiata and some other Italian breeds. A unique morphological feature present in Banat and Somali wild donkeys, but also in Amiata donkeys, black stripes on legs, suggests that the origin of Clade 2 donkeys may be much more complex than previously thought. Actions to preserve the Banat donkey, a valuable but critically endangered genetic resource (<100 individuals), are urgent.

Genetic diversity and maternal origin of Northeast African and South American donkey populations

To investigate the mtDNA variation and origin of maternal lineages in South American donkeys and to reassess the domestication of donkeys in northeast Africa, we analyzed sequences (489 bp of the D-loop) from 323 domestic donkeys sampled from Peru, Brazil, Ethiopia and Egypt. Altogether, the 323 sequences displayed 53 different haplotypes (45 in Ethiopia, 14 in Egypt, eight in Peru and six in Brazil). Among the four populations, Egyptian donkeys possessed the highest haplotype diversity (0.910 ± 0.032), followed by Brazilian donkeys (0.879 ± 0.060). The Clade I haplotypes dominated in Peruvian donkeys (65%), whereas Clade II haplotypes dominated in Brazilian donkeys (67%). Estimates of F_ST values showed a high genetic differentiation between Peruvian and Brazilian donkey populations (F_ST  = 0.4066), which could be explained by the complex introduction history of South American donkeys. Phylogeographic analysis indicates that northeast Africa could be the most probable domestication center for Clade I donkeys. Analysis of molecular variance confirmed a weak genetic structure in domestic donkey populations among four continents (Europe, Asia, Africa and South America).

New insights into the origin and the genetic status of the Balkan donkey from Serbia

The Balkan donkey (Equus asinus L.) is commonly regarded as a large-sized, unselected, unstructured and traditionally managed donkey breed. We assessed the current genetic status of the three largest E. asinus populations in the central Balkans (Serbia) by analysing the variability of nuclear microsatellites and the mitochondrial (mtDNA) control region of 77 and 49 individuals respectively. We further analysed our mtDNA dataset along with 209 published mtDNA sequences of ancient and modern individuals from 19 European and African populations to provide new insights into the origin and the history of the Balkan donkey. Serbian donkey populations are highly genetically diverse at both the nuclear and mtDNA levels despite severe population decline. Traditional Balkan donkeys in Serbia are rather heterogeneous; we found two groups of individuals with similar phenotypic features, somewhat distinct nuclear backgrounds and different proportions of mtDNA haplotypes belonging to matrilineal Clades 1 and 2. Another group, characterized by larger body size, different coat colour, distinct nuclear gene pool and predominantly Clade 2 haplotypes, was delineated as the Banat donkey breed. The maternal landscape of the large Balkan donkey population is highly heterogeneous and more complex than previously thought. Given the two independent domestication events in donkeys, multiple waves of introductions into the Balkans from Greece are hypothesized. Clade 2 donkeys probably appeared in Greece prior to those belonging to Clade 1, whereas expansion and diversification of Clade 1 donkeys within the Balkans predated that of Clade 2 donkeys.

Mitochondrial DNA genetic diversity in six Italian donkey breeds (Equus asinus)

Donkeys have played an important role in agricultural land practices and in human historical periods of recent past and, still today, are used as a working power in several world areas. The objective of this study was to identify genetic variability in six Italian donkey breeds using mtDNA D-loop. Fifteen haplotypes, grouped in three haplogroups, were identified. The genetic indices were informative and showed a high population genetic variability. The results of AMOVA analyses based on geographic structuring of Italian populations highlighted that the majority of the observed variance is due to differences among samples within breeds. Comparison among Italian haplotypes and mtDNA D-loop sequences belonging to European domestic and Ethiopian donkeys and wild asses, clearly define two clades referred to Nubian lineage. The results can be useful to complement safeguard planes for donkey breeds that are considered to extinction endangered.