Phylogeny involves the study of the evolutionary relationships and genetic lineage of horses within the broader context of equids and other related species. This field examines the genetic, morphological, and paleontological evidence to trace the ancestry and diversification of horses over time. Research in equine phylogeny explores the genetic markers, fossil records, and comparative anatomy that shed light on the evolutionary history and adaptations of horses. This page compiles peer-reviewed research studies and scholarly articles that investigate the evolutionary pathways, genetic variations, and historical development of horses, providing insights into their biological and ecological evolution.
Piras FM, Nergadze SG, Poletto V, Cerutti F, Ryder OA, Leeb T, Raimondi E, Giulotto E.Horses, asses and zebras belong to the genus Equus and are the only extant species of the family Equidae in the order Perissodactyla. In a previous work we demonstrated that a key factor in the rapid karyotypic evolution of this genus was evolutionary centromere repositioning, that is, the shift of the centromeric function to a new position without alteration of the order of markers along the chromosome. In search of previously undiscovered evolutionarily new centromeres, we traced the phylogeny of horse chromosome 5, analyzing the order of BAC markers, derived from a horse genomic library, in...
Ghanem YM, Fukushi H, Ibrahim ES, Ohya K, Yamaguchi T, Kennedy M.Viruses related to equine herpesvirus type 1 (EHV-1) were isolated from an aborted fetus of an onager (Equus hemionus) in 1984, an aborted fetus of Grevy's zebra (Equus grevyi) in 1984 and a Thomson's gazelle (Gazella thomsoni) with nonsuppurative encephalitis in 1996, all in the USA. The mother of the onager fetus and the gazelle were kept near plains zebras (Equus burchelli). In phylogenetic trees based on the nucleotide sequences of the genes for glycoproteins B (gB), I (gI), and E (gE), and teguments including ORF8 (UL51), ORF15 (UL45), and ORF68 (US2), the onager, Grevy's zebra and gazell...
Quan M, van Vuuren M, Howell PG, Groenewald D, Guthrie AJ.Between 2004 and 2006, 145 African horse sickness viruses (AHSV) were isolated from blood and organ samples submitted from South Africa to the Faculty of Veterinary Science, University of Pretoria. All nine serotypes were represented, with a range of 3-60 isolates per serotype. The RNA small segment 10 (S10) nucleotide sequences of these isolates were determined and the phylogeny investigated. AHSV, bluetongue virus (BTV) and equine encephalosis virus (EEV) all formed monophyletic groups and BTV was genetically closer to AHSV than EEV. This study confirmed the presence of three distinct S10 ph...
Orlando L, Male D, Alberdi MT, Prado JL, Prieto A, Cooper A, Hänni C.Hippidions are past members of the equid lineage which appeared in the South American fossil record around 2.5 Ma but then became extinct during the great late Pleistocene megafaunal extinction. According to fossil records and numerous dental, cranial, and postcranial characters, Hippidion and Equus lineages were expected to cluster in two distinct phylogenetic groups that diverged at least 10 MY, long before the emergence of the first Equus. However, the first DNA sequence information retrieved from Hippidion fossils supported a striking different phylogeny, with hippidions nesting inside a p...
Strüder-Kypke MC, Kornilova OA, Lynn DH.Ciliates of the subclass Trichostomatia inhabit the fermentative regions of the digestive tract of herbivores. Most available small subunit ribosomal RNA (SSrRNA) gene sequences of trichostomes are from species isolated from the rumen of cattle or sheep and from marsupials. No ciliate species endosymbiotic in horses has yet been analyzed. We have sequenced the SSrRNA genes of five ciliate species, isolated from the cecum and colon of four Yakut horses: Cycloposthium edentatum, Cycloposthium ishikawai, Tripalmaria dogieli, Cochliatoxum periachtum, and Paraisotricha colpoidea. Based on their mor...
Xu S, Luosang J, Hua S, He J, Ciren A, Wang W, Tong X, Liang Y, Wang J, Zheng X.To investigate genetic mechanisms of high altitude adaptations of animals living in the Tibetan Plateau, three mitochondrial genomes (mt-genome) of Tibetan horses living in Naqu (4,500 m) of Tibetan, Zhongdian (3,300 m) and Deqin (3,100 m) of Yunnan province were sequenced. The structures and lengths of these three mt-genomes are similar to the Cheju horse, which is related to Tibetan horses, but little shorter than the Swedish horse. The pair-wise identity of these three horses on nucleotide level is more than 99.3%. When the gene encoding the mitochondrial protein of Tibetan horses was analy...
McGahern A, Bower MA, Edwards CJ, Brophy PO, Sulimova G, Zakharov I, Vizuete-Forster M, Levine M, Li S, MacHugh DE, Hill EW.Equine mitochondrial DNA (mtDNA) phylogeny reconstruction reveals a complex pattern of variation unlike that seen in other large domesticates. It is likely that this pattern reflects a process of multiple and repeated, although not necessarily independent, domestication events. Until now, no clear geographic affiliation of clades has been apparent. In this study, amova analyses have revealed a significant non-random distribution of the diversity among equine populations when seven newly sequenced Eurasian populations were examined in the context of previously published sequences. The associati...
Mittelholzer C, Stadejek T, Johansson I, Baule C, Ciabatti I, Hannant D, Paton D, Autorino GL, Nowotny N, Belák S.To determine a conclusive phylogeny, equine arteritis viruses from Italy, Austria, Hungary, Sweden, South Africa and other parts of the world were analysed by reverse-transcription polymerase chain reaction amplification and direct sequencing. The nucleotide sequences corresponding to the variable part of the large glycoprotein GP5, specified by open reading frame 5, were compared and added to a previously published phylogenetic tree in which a clear division between 'European' and 'American' type viruses had been established. Adding the sequences determined in this study and new sequences ret...
Elsheikha HM, Lacher DW, Mansfield LS.Phylogenetic analyses based on sequences of the nuclear-encoded small subunit rRNA (ssurRNA) gene were performed to examine the origin, phylogeny, and biogeographic relationships of Sarcocystis neurona isolates from opossums and horses from the State of Michigan, USA, in relation to other cyst-forming coccidia. A total of 31 taxa representing all recognized subfamilies and genera of Sarcocystidae were included in the analyses with clonal isolates of two opossum and two horse S. neurona. Phylogenies obtained by the four tree-building methods were consistent with the classical taxonomy based on ...
Vollmerhaus B, Roos H, Gerhards H, Knospe C.The canine teeth of the horse developed phylogenically from the simple, pointed, short-rooted tooth form of the leaf eating, in pairs living, Eocene horse Hyracotherium and served up to the Oligocene as a means of defense (self preservation). In the Miocene the living conditions of the Merychippus changed and they took to eating grass and adopted as a new behavior the life in a herd. The canine teeth possibly played an important role in fights for social ranking; they changed from a crown form to knife-like shape. In the Pliohippus the canine tooth usually remained in male horses and since the...
Yang YH, Kim KI, Cothran EG, Flannery AR.We used sequence polymorphism of the mitochondrial DNA D-loop (968 bp excluding the tandem repeat region) to determine genetic diversity of horses inhabiting Cheju (a southern island of Korea). Seventeen haplotypes with frequencies from 1.5 to 21.5% were found among 65 Cheju horse samples. Genetic diversity (h) of the 17 haplotypes was calculated to be 0.91, indicating that the extant Cheju horse population consists of diverse genetic groups in their maternal lineage. Phylogenetic analysis showed that 17 types of Cheju (D-loop sequences determined), 5 Mongolian, 6 Arabian, 3 Belgian, 2 Tsushim...
Holmes EC, Ellis SA.We carried out an analysis of partial sequences from expressed major histocompatibility complex (MHC) class I genes isolated from a range of equid species and more distantly related members of the mammalian order Perissodactyla. Phylogenetic analysis revealed a minimum of six groups, five of which contained genes and alleles that are found in equid species and one group specific to the rhinoceros. Four of the groups contained only one, or very few sequences, indicating the presence of relatively nonpolymorphic loci, while another group contained the majority of the equid sequences identified. ...
Fenger CK, Granstrom DE, Langemeier JL, Gajadhar A, Cothran G, Tramontin RR, Stamper S, Dubey JP.Sarcocystis neurona is a coccidial parasite that causes a neurologic disease of horses in North and South America. The natural host species are not known and classification is based on ultrastructural analysis. The small subunit ribosomal RNA (SSURNA) gene of S. neurona was amplified using polymerase chain reaction techniques and sequenced by Sanger sequencing reactions. The sequence was compared with partial sequences of S. muris, S. gigantea, S. tenella, S. cruzi, S. arieticanis, S. capracanis, Toxoplasma gondii, Eimeria tenella, and Cryptosporidium parvum. Alignments of available sites for ...
Prado JL, Alberdi MT.The contemporary South American mammalian communities were determined by the emergence of the Isthmus of Panama and by the profound climatic oscillations during the Pleistocene. Horses and gomphotheres were 2 very conspicuous groups of immigrant mammals from North America that arrived in South America during the Pleistocene. The present study compiles updated data on the phylogeny, systematics and ecology of both groups in South America. The horses in South America are represented by 2 genera, Hippidion and Equus, as are the gomphotheres, represented by Cuvieronius and Stegomastodon. Both gene...
Famoso NA, Davis EB.Four groups of equids, "Anchitheriinae," Merychippine-grade Equinae, Hipparionini, and Equini, coexisted in the middle Miocene, but only the Equini remains after 16 Myr of evolution and extinction. Each group is distinct in its occlusal enamel pattern. These patterns have been compared qualitatively but rarely quantitatively. The processes influencing the evolution of these occlusal patterns have not been thoroughly investigated with respect to phylogeny, tooth position, and climate through geologic time. We investigated Occlusal Enamel Index, a quantitative method for the analysis of the comp...
Sohail Ashraf M, Basheer A, Iqbal F, Zahoor I.The current study aimed to evaluate the genetic diversity, level of admixture, and phylogenetic relationship, of the Pakistani horse breeds, along with their morphological characterization. Data for the body measurements showed that Morna horses had the highest values of body height, body length, chest girth, leg length, and head length, whereas the Baluchi horses had the lowest values for these traits. For the genetic diversity 64 animals, 15/breed except for Baluchi(14) and Topras(05), were genotyped by using the 17-plex equine genotyping kit. The AMOVA results showed that 13% of genetic div...
Sonali , Giri SK, Unnati , Nayan V, Legha RA, Pal Y, Bhardwaj A.India has well documented horse and pony breeds; however, the population is well diversified in different geographical regions. The Myostatin gene is one of the most profoundly studied genetic components for the detection of SNP's for the performance analysis in horses. In the present study, the MSTN exon 2 partial cds were amplified, sequenced and characterized in about 60 samples of eight different breeds of Indian horses. The results indicated the transition of Thymine to Cytosine (T>C) as single nucleotide polymorphisms in the partial sequence of exon 2 of the MSTN gene at two different...
Vollmerhaus B, Roos H, Gerhards H, Knospe C.The canine teeth of the horse developed phylogenically from the simple, pointed, short-rooted tooth form of the leaf eating, in pairs living, Eocene horse Hyracotherium and served up to the Oligocene as a means of defense (self preservation). In the Miocene the living conditions of the Merychippus changed and they took to eating grass and adopted as a new behavior the life in a herd. The canine teeth possibly played an important role in fights for social ranking; they changed from a crown form to knife-like shape. In the Pliohippus the canine tooth usually remained in male horses and since the...
Abdel-Gaber R, Al Quraishy S, Dkhil MA, Alghamdi J, Al-Shaebi E.Sarcocystosis is a parasitic disease caused by an intracellular protozoan parasite Sarcocystis belonging to the phylum Apicomplexa. These parasites have a requisite two-host life cycle. Recently, there are many Sarcocystis species that identified morphologically. In the present study, diaphragmatic muscle samples from the domestic horse (Equus caballus) were examined for Sarcocystis infection. The natural infection with sarcocysts was recorded to be 62·5% for only microcysts in the infected muscles. Molecular analysis using the 18S rRNA gene was conducted to swiftly and accurately identify th...
Vershinina AO, Kapp JD, Baryshnikov GF, Shapiro B.Museum collections are essential for reconstructing and understanding past biodiversity. Many museum specimens are, however, challenging to identify. Museum samples may be incomplete, have an unusual morphology, or represent juvenile individuals, all of which complicate accurate identification. In some cases, inaccurate identification can lead to false biogeographic reconstructions with cascading impacts on paleontological and paleoecological research. Here, we analyzed an unusual Equid mandible found in the Far North of the Taymyr peninsula that was identified morphologically as Equus hemionu...
Tinkler SH, Villa L, Manfredi MT, Walshe N, Jahns H.This is the first report of Besnoitia bennetti in donkeys in Ireland. B. bennetti, an apicomplexan protozoan parasite specific to equids, is an emerging pathogen in Europe. This parasite forms chronic intracytoplasmic cysts in cells of the mesenchymal lineage, mainly fibroblasts, in the skin, sclera and mucosa. Clinical signs in affected equine hosts vary from mild to severe debilitating disease. Little is known of the phylogeny, epidemiology or transmission of B. bennetti infection in donkeys, mules or horses. Methods: Two cases of besnoitiosis in donkeys are presented. Both donkeys were born...
Thompson MA, McCann BE, Rhen T, Simmons R.Theodore Roosevelt National Park (TRNP) manages a herd of feral horses () which was present on the landscape prior to the establishment of the park. The population presents a unique scenario in that it has experienced fairly intensive and well-documented management since the park's establishment, including herd size reductions, intentional introduction of diversity, and subsequent attempts to remove introduced lineages. This provides an interesting case study on the genetic effects of diverse evolutionary forces on an isolated feral population. To explore the effects of these forces and clarif...
Stasiak K, Dunowska M, Rola J.Equine rhinitis A (ERAV) and B (ERBV) viruses are respiratory pathogens with worldwide distribution. The current study aimed to determine the frequency of infection of ERAV and ERBV among horses and foals at Polish national studs, and to determine genetic variability within the viruses obtained. Virus-specific quantitative RT-PCR assays targeting a 5' untranslated region were used to screen nasal swabs collected from 621 horses at 16 national horse studs from throughout Poland, including 553 healthy horses and 68 horses with respiratory disease. A partial DNA polymerase gene was amplified and ...
Mohtasebi S, Ahn S, Rosa B, Moyes K, Kuzmina TA, Gilleard JS, Poissant J.Equids are infected by a diversity of gastrointestinal nematode parasites, including 64 species of equine strongyle nematodes from19 genera. Despite numerous surveys of horse strongyles worldwide, certain geographic regions and rare species remain understudied. In 1964, a new species of equine strongyle, Cylicocyclus pekingensis, was described from a donkey in China. Subsequently, this species was recorded in horses from Kazakhstan and reclassified as Hsiungia pekingensis (K'ung and Yang, 1964), the only species in this genus. Since then, H. pekingensis has not been reported elsewhere, with li...
Zhao Y, Ma S, Sun Y, Huang Y, Deng Y.To identify a thermophilic bacterium from horse manure to degrade cellulose efficiently, and to enrich microbial resources producing cellulolytic ethanol by co-culturing with thermophilic ethanol producing bacterium. Methods: We used Hungate anaerobic technique to isolate a strain named as HCp from horse manure mixed culture; its phylogeny was identified through 16S rDNA sequencing. Enzymatic assays were determined using DNS method. Results: The isolated HCp cells were straight with rods size of(0.35-0.50) microm x (2.42-6.40) microm, in the form of single or paring. This strain belongs to a s...
Stasiak K, Dunowska M, Rola J.Equid herpesvirus 5 (EHV-5) comprises a group of heterogeneous viruses with a worldwide distribution. Primary infection typically occurs early in life, which is followed by latency and periodic recrudescence of the virus. The aim of this study was to determine the genetic variation of EHV-5 in individual animals over time and to determine the dynamics of EHV-5 spread among selected mare-foal pairs at three horse studs. The partial glycoprotein B () gene was amplified from archival nasal swab samples. Sequences from 3-5 clones from each PCR product were compared using identity matrix, phylogeny...
