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Topic:Phylogenetic Analysis

Phylogenetic analysis involves the study of the evolutionary relationships among horse species and their ancestors. This scientific approach uses genetic data to construct phylogenetic trees that illustrate the evolutionary pathways and divergence of different equine lineages. By analyzing DNA sequences, researchers can infer the genetic similarities and differences among horse breeds and their relatives, providing insights into their evolutionary history and adaptation processes. Phylogenetic analysis can also help identify genetic markers associated with specific traits or health conditions. This page compiles peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and implications of phylogenetic analysis in understanding horse evolution and diversity.
West Nile virus in Morocco, 2003.
Emerging infectious diseases    March 9, 2005   Volume 11, Issue 2 306-309 doi: 10.3201/eid1102.040817
Schuffenecker I, Peyrefitte CN, el Harrak M, Murri S, Leblond A, Zeller HG.West Nile virus (WNV) reemerged in Morocco in September 2003, causing an equine outbreak. A WNV strain isolated from a brain biopsy was completely sequenced. On the basis of phylogenetic analyses, Moroccan WNV strains isolated during the 1996 and 2003 outbreaks were closely related to other strains responsible for equine outbreaks in the western Mediterranean basin.
Sequence analysis of the msp4 gene of Anaplasma phagocytophilum strains.
Journal of clinical microbiology    March 8, 2005   Volume 43, Issue 3 1309-1317 doi: 10.1128/JCM.43.3.1309-1317.2005
de la Fuente J, Massung RF, Wong SJ, Chu FK, Lutz H, Meli M, von Loewenich FD, Grzeszczuk A, Torina A, Caracappa S, Mangold AJ, Naranjo V, Stuen S....The causative agent of human granulocytic ehrlichiosis was recently reclassified as Anaplasma phagocytophilum, unifying previously described bacteria that cause disease in humans, horses, dogs, and ruminants. For the characterization of genetic heterogeneity in this species, the homologue of Anaplasma marginale major surface protein 4 gene (msp4) was identified, and the coding region was PCR amplified and sequenced from a variety of sources, including 50 samples from the United States, Germany, Poland, Norway, Italy, and Switzerland and 4 samples of A. phagocytophilum-like organisms obtained f...
Genetic clustering of Borna disease virus natural animal isolates, laboratory and vaccine strains strongly reflects their regional geographical origin.
The Journal of general virology    January 22, 2005   Volume 86, Issue Pt 2 385-398 doi: 10.1099/vir.0.80587-0
Kolodziejek J, Dürrwald R, Herzog S, Ehrensperger F, Lussy H, Nowotny N.The aim of this study was to gain more detailed insights into the genetic evolution and variability of Borna disease virus (BDV). Phylogenetic analyses were performed on field viruses originating from naturally infected animals, the BDV vaccine strain 'Dessau', four widely used laboratory strains and the novel BDV subtype No/98. Four regions of the BDV genome were analysed: the complete p40, p10 and p24 genes and the 5'-untranslated region of the X/P transcript. BDV isolates from the same geographical area exhibited a clearly higher degree of identity to each other than to BDV isolates from ot...
Nicoletella semolina gen. nov., sp. nov., a new member of Pasteurellaceae isolated from horses with airway disease.
Journal of clinical microbiology    December 8, 2004   Volume 42, Issue 12 5542-5548 doi: 10.1128/JCM.42.12.5542-5548.2004
Kuhnert P, Korczak B, Falsen E, Straub R, Hoops A, Boerlin P, Frey J, Mutters R.Gram-negative, nonmotile bacteria that are catalase, oxidase, and urease positive are regularly isolated from the airways of horses with clinical signs of respiratory disease. On the basis of the findings by a polyphasic approach, we propose that these strains be classified as Nicoletella semolina gen. nov, sp. nov., a new member of the family Pasteurellaceae. N. semolina reduces nitrate to nitrite but is otherwise biochemically inert; this includes the lack of an ability to ferment glucose and other sugars. Growth is fastidious, and the isolates have a distinctive colony morphology, with the ...
Equine papillomavirus type 1: complete nucleotide sequence and characterization of recombinant virus-like particles composed of the EcPV-1 L1 major capsid protein.
Biochemical and biophysical research communications    October 16, 2004   Volume 324, Issue 3 1108-1115 doi: 10.1016/j.bbrc.2004.09.154
Ghim SJ, Rector A, Delius H, Sundberg JP, Jenson AB, Van Ranst M.Equus caballus papillomavirus type 1 (EcPV-1) was isolated from a cutaneous papilloma, the most common neoplasm in horses. The complete EcPV-1 nucleotide sequence and genomic organization were determined. Phylogenetic analysis showed that EcPV-1 is a close-to-root papillomavirus, with only distant relationships to the fibropapillomaviruses and the benign cutaneous papillomaviruses. To produce EcPV-1 virus-like particles (VLPs), the EcPV-1 L1 major capsid protein was expressed in insect cells using a recombinant baculovirus vector. The self-assembled EcPV-1 VLPs were morphologically indistingui...
Phylogenetic analysis of West Nile virus, Nuevo Leon State, Mexico.
Emerging infectious diseases    August 25, 2004   Volume 10, Issue 7 1314-1317 doi: 10.3201/eid1007.030959
Blitvich BJ, Fernández-Salas I, Contreras-Cordero JF, Loroño-Pino MA, Marlenee NL, Díaz FJ, González-Rojas JI, Obregón-Martínez N....West Nile virus RNA was detected in brain tissue from a horse that died in June 2003 in Nuevo Leon State, Mexico. Nucleotide sequencing and phylogenetic analysis of the premembrane and envelope genes showed that the virus was most closely related to West Nile virus isolates collected in Texas in 2002.
Detection and identification of equine Theileria and Babesia species by reverse line blotting: epidemiological survey and phylogenetic analysis.
Veterinary parasitology    July 22, 2004   Volume 123, Issue 1-2 41-54 doi: 10.1016/j.vetpar.2004.04.010
Nagore D, García-Sanmartín J, García-Pérez AL, Juste RA, Hurtado A.Specific oligonucleotide probes were designed to develop a new and highly sensitive reverse line blot assay to detect and identify simultaneously different Theileria and Babesia species in horses. The amplified hypervariable V4 region of the 18S rRNA gene was hybridised against different generic and species-specific probes. The survey was conducted over 243 samples of equine blood divided into three different groups: group 1, 24 horses presented as possible clinical piroplasmosis; group 2, 181 clinically healthy free-ranging horses exposed to ticks; group 3, 38 riding horses with unrelated pat...
Streptococcus devriesei sp. nov., from equine teeth.
Systematic and applied microbiology    March 30, 2004   Volume 27, Issue 2 146-150 doi: 10.1078/072320204322881754
Collins MD, Lundström T, Welinder-Olsson C, Hansson I, Wattle O, Hudson RA, Falsen E.Phenotypic and phylogenetic studies were performed on four unidentified Gram-positive staining, catalase-negative, alpha-hemolytic Streptococcus-like organisms recovered from the teeth of horses. SDS PAGE analysis of whole-cell proteins and comparative 16S rRNA gene sequencing demonstrated the four strains were highly related to each other but that they did not correspond to any recognised species of the genus Streptococcus. Phylogenetic analysis based on 16S rRNA gene sequences showed the unidentified organisms form a hitherto unknown sub-line within the Streptococcus genus, displaying a clos...
Genetic characterization of Pompeii and Herculaneum Equidae buried by Vesuvius in 79 AD.
Journal of cellular physiology    March 25, 2004   Volume 199, Issue 2 200-205 doi: 10.1002/jcp.10461
Di Bernardo G, Galderisi U, Del Gaudio S, D'Aniello A, Lanave C, De Robertis MT, Cascino A, Cipollaro M.DNA extracted from the skeletons of five equids discovered in a Pompeii stable and of a horse found in Herculaneum was investigated. Amino acid racemization level was consistent with the presence of DNA. Post-mortem base modifications were excluded by sequencing a 146 bp fragment of the 16S rRNA mitochondrial gene. Sequencing of a 370 bp fragment of mitochondrial (mt)DNA control region allowed the construction of a phylogenetic tree that, along with sequencing of nuclear genes (epsilon globin, gamma interferon, and p53) fragments, gave us the possibility to address some questions puzzling arch...
Alternate circulation of recent equine-2 influenza viruses (H3N8) from two distinct lineages in the United States.
Virus research    March 17, 2004   Volume 100, Issue 2 159-164 doi: 10.1016/j.virusres.2003.11.019
Lai AC, Rogers KM, Glaser A, Tudor L, Chambers T.Phylogenetic and antigenic analyses indicate that recent circulating equine-2 influenza viruses in the United States have been alternating between two genetic and antigenic distinct lineages since 1996. The evolution rates for these two lineages, the Kentucky and the Florida lineage, are very similar. For the earlier isolates in the Kentucky lineage, there are multiple and sequential nonsynonymous substitutions at antigenic sites B and D. However, there are no changes at any of these antigenic sites for KY98 and OK00. In the Florida lineage, except for NY99 with one amino acid substitution at ...
Detection and nucleotide sequencing of a DNA-packaging protein gene of equine gammaherpesviruses. Kleiboeker SB, Turnquist SE, Johnson PJ, Kreeger JM.In previous studies, novel putative viral pathogens designated that asinine herpesvirus 4 (AsHV4) and asinine herpesvirus 5 (AsHV5) were associated with fatal interstitial pneumonia in donkeys (Equus asinus). Nucleotide sequence analysis of a portion of the DNA polymerase gene identified these putative pathogens as herpesviruses and possibly as members of the Gammaherpesvirinae subfamily. Although similar to equine herpesvirus 2 (EHV2) and equine herpesvirus 5 (EHV5), sequence diversity was observed among the detected viruses. In this study, novel sequence is reported for a DNA-packaging prote...
Fixed nucleotide differences on the Y chromosome indicate clear divergence between Equus przewalskii and Equus caballus.
Animal genetics    December 23, 2003   Volume 34, Issue 6 453-456 doi: 10.1046/j.0268-9146.2003.01044.x
Wallner B, Brem G, Müller M, Achmann R.The phylogenetic relationship between Equus przewalskii and E. caballus is often a matter of debate. Although these taxa have different chromosome numbers, they do not form monophyletic clades in a phylogenetic tree based on mtDNA sequences. Here we report sequence variation from five newly identified Y chromosome regions of the horse. Two fixed nucleotide differences on the Y chromosome clearly display Przewalski's horse and domestic horse as sister taxa. At both positions the Przewalski's horse haplotype shows the ancestral state, in common with the members of the zebra/ass lineage. We discu...
Characterization of the horse (Equus caballus) IGHA gene.
Immunogenetics    October 15, 2003   Volume 55, Issue 8 552-560 doi: 10.1007/s00251-003-0617-2
Wagner B, Greiser-Wilke I, Antczak DF.Nucleotide sequences of the immunoglobulin constant heavy chain genes of the horse have been described for IGHM, IGHG and IGHE genes, but not for IGHA. Here, we provide the nucleotide sequence of the genomic IGHA gene of the horse ( Equus caballus), including its secretion region and the transmembrane exon. The equine IGHA gene shows the typical structure of a mammalian IGHA gene, with only three exons, separated by two introns of similar size. The hinge exon is located at the 5' end of the CH2 exon and encodes a hinge region of 11 amino acids, which contains five proline residues. The coding ...
Microsatellite variation in Japanese and Asian horses and their phylogenetic relationship using a European horse outgroup.
The Journal of heredity    October 15, 2003   Volume 94, Issue 5 374-380 doi: 10.1093/jhered/esg079
Tozaki T, Takezaki N, Hasegawa T, Ishida N, Kurosawa M, Tomita M, Saitou N, Mukoyama H.The genetic relationships of seven Japanese and four mainland-Asian horse populations, as well as two European horse populations, were estimated using data for 20 microsatellite loci. Mongolian horses showed the highest average heterozygosities (0.75-0.77) in all populations. Phylogenetic analysis showed the existence of three distinct clusters supported by high bootstrap values: the European cluster (Anglo-Arab and thoroughbreds), the Hokkaido-Kiso cluster, and the Mongolian cluster. The relationships of these clusters were consistent with their geographical distributions. Basing our assumpti...
Lateral transmission of equine arteritis virus among Lipizzaner stallions in South Africa.
Equine veterinary journal    October 1, 2003   Volume 35, Issue 6 596-600 doi: 10.2746/042516403775467162
Guthrie AJ, Howell PG, Hedges JF, Bosman AM, Balasuriya UB, McCollum WH, Timoney PJ, MacLachlan NJ.A serological study conducted in 1995 revealed that 7 stallions at the Lipizzaner Centre, Gauteng, South Africa, were seropositive for antibody to equine arteritis virus (EAV). A Lipizzaner stallion imported into South Africa from Yugoslavia in 1981 had previously (1988) been confirmed to be an EAV carrier. Despite being placed under life-long breeding quarantine, EAV had been transmitted between stallions at the Lipizzaner Centre. Objective: To investigate the phylogenetic relationships between the strain of EAV shed in the semen of the original carrier stallion and strains recovered from the...
Molecular phylogenetics and diagnosis of soil and clinical isolates of Halicephalobus gingivalis (Nematoda: Cephalobina: Panagrolaimoidea), an opportunistic pathogen of horses.
International journal for parasitology    September 18, 2003   Volume 33, Issue 10 1115-1125 doi: 10.1016/s0020-7519(03)00134-6
Nadler SA, Carreno RA, Adams BJ, Kinde H, Baldwin JG, Mundo-Ocampo M.Phylogenetic relationships among six isolates of Halicephalobus gingivalis (Stefanski, 1954), a species with pathogenic potential in horses and humans, were evaluated using DNA sequences from the nuclear large-subunit ribosomal RNA (LSU rDNA) gene. Sequences from nematodes obtained from in vitro cultures (soil or clinical sources), or isolated from infected horse tissues, were compared. Gene sequences from a fatal equine clinical case from southern California and a free-living isolate recovered from southern California soil showed no fixed differences. Sequences from isolates representing two ...
VP2 gene phylogenetic characterization of field isolates of African horsesickness virus serotype 7 circulating in South Africa during the time of the 1999 African horsesickness outbreak in the Western Cape.
Virus research    June 5, 2003   Volume 93, Issue 2 159-167 doi: 10.1016/s0168-1702(03)00076-5
Koekemoer JJ, Paweska JT, Pretorius PJ, van Dijk AA.We present the first VP2-gene phylogenetic analysis of African horsesickness (AHS) viruses within a serotype. Thirteen AHSV 7 isolates were obtained from cases that occurred in South Africa during 1998-1999, and three were historical AHSV 7 isolates. The goals were to start a database of isolates of known location and time of isolation and to determine if we could identify the origin of an AHS outbreak in the surveillance area in the Western Cape. We prepared full-length cDNA copies of the VP2-genes of the isolates. Nucleic acid sequence data of a 786 bp region was used to characterize the gen...
Genetic relationship between Mongolian and Norwegian horses?
Animal genetics    February 13, 2003   Volume 34, Issue 1 55-58 doi: 10.1046/j.1365-2052.2003.00922.x
Bjørnstad G, Nilsen NØ, Røed KH.Human populations of Central Asian origin have contributed genetic material to northern European populations. It is likely that migrating humans carried livestock to ensure food and ease transportation. Thus, eastern genes could also have dispersed to northern European livestock populations. Using microsatellite data, we here report that the essentially different genetic distances DA and (deltamu)2 and their corresponding phylogenetic trees show close associations between the Mongolian native horse and northern European horse breeds. The genetic distances between the northern European breeds a...
Crossiella equi sp. nov., isolated from equine placentas.
International journal of systematic and evolutionary microbiology    January 2, 2003   Volume 52, Issue Pt 6 2169-2173 doi: 10.1099/ijs.0.02257-0
Donahue JM, Williams NM, Sells SF, Labeda DP.Over the course of the past decade, actinomycetes have been isolated from the placentas of horses diagnosed with nocardioform placentitis. The incidence of this infection has generally been low, with typically no more than 30 animals affected in most years, but the incidence increased through 1999, with placentas from 144 mares found to be infected. Approximately half of the cases result in loss of the foal. A typical actinomycete with branching mycelium was isolated from placental lesions, and a comparison of the sequence of the 16S rDNA gene against the public databases indicated a relations...
Genetic diversity of Cheju horses (Equus caballus) determined by using mitochondrial DNA D-loop polymorphism.
Biochemical genetics    July 26, 2002   Volume 40, Issue 5-6 175-186 doi: 10.1023/a:1015884125507
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...
Mitochondrial DNA and the origins of the domestic horse.
Proceedings of the National Academy of Sciences of the United States of America    July 18, 2002   Volume 99, Issue 16 10905-10910 doi: 10.1073/pnas.152330099
Jansen T, Forster P, Levine MA, Oelke H, Hurles M, Renfrew C, Weber J, Olek K.The place and date of the domestication of the horse has long been a matter for debate among archaeologists. To determine whether horses were domesticated from one or several ancestral horse populations, we sequenced the mitochondrial D-loop for 318 horses from 25 oriental and European breeds, including American mustangs. Adding these sequences to previously published data, the total comes to 652, the largest currently available database. From these sequences, a phylogenetic network was constructed that showed that most of the 93 different mitochondrial (mt)DNA types grouped into 17 distinct p...
Evolution of the six horse IGHG genes and corresponding immunoglobulin gamma heavy chains.
Immunogenetics    July 4, 2002   Volume 54, Issue 5 353-364 doi: 10.1007/s00251-002-0458-4
Wagner B, Greiser-Wilke I, Wege AK, Radbruch A, Leibold W.It is generally assumed that the different mammalian IgG isotypes have developed during evolution by duplications of a common ancestor gamma heavy chain constant region gene (IGHG). In contrast to other species studied so far, which express between one and four IGHG genes, the horse (Equus caballus) genome contains six IGHG genes, and it has been postulated that they all can be expressed. For determination of the evolutionary history of the six horse IGHG genes, genomic DNA and cDNA of the IGHG genes were sequenced. The structure of these genes with reference to exons and introns was determine...
Fusobacterium equinum sp. nov., from the oral cavity of horses.
International journal of systematic and evolutionary microbiology    January 5, 2002   Volume 51, Issue Pt 6 1959-1963 doi: 10.1099/00207713-51-6-1959
Dorsch M, Lovet DN, Bailey GD.Two strains of gram-negative, anaerobic, non-sporulating rod that were isolated from the normal oral cavity and oral-associated disease from horses and which phenotypically resembled Fusobacterium necrophorum were characterized by sequencing of the 16S rRNA gene, phylogenetic analysis, DNA-DNA hybridization and phenotypic characterization. The results placed the novel strains as distinct members of the genus Fusobacterium. The novel species Fusobacterium equinum sp. nov. is proposed, with strain VPB 4027T (= NCTC 13176T = JCM 11174T) as the type strain.
Genetic variation of the second exon of ELA-DRB genes in Argentine Creole horses.
Animal genetics    October 31, 2001   Volume 32, Issue 5 257-263 doi: 10.1046/j.1365-2052.2001.00779.x
Díaz S, Giovambattista G, Dulout FN, Peral-García P.Genetic variation in the equine leucocyte antigen-DRB (ELA-DRB) second exon was investigated using polymerase chain reaction (PCR) amplification, restriction fragment length polymorphism (RFLP) of PCR products (PCR-RFLP) and deoxyribonucleic acid (DNA) sequencing. Eight distinct PCR-RFLP patterns could be identified in the studied Argentine Creole (AC) horses. The number of observed patterns per individual ranged from four to six, thus confirming the presence of multiple DRB copies in AC horses. Three PCR-RFLP alleles and three new sequences were identified. The estimated rates of synonymous a...
Equine rhinitis B virus: a new serotype.
The Journal of general virology    October 17, 2001   Volume 82, Issue Pt 11 2641-2645 doi: 10.1099/0022-1317-82-11-2641
Huang JA, Ficorilli N, Hartley CA, Wilcox RS, Weiss M, Studdert MJ.Equine rhinovirus serotype 3 isolate P313/75 was assigned, with an unclassified genus status, to the family PICORNAVIRIDAE: The sequence from the 5' poly(C) tract to the 3' poly(A) tract of P313/75 was determined. The sequence is 8821 bases in length and contains a potential open reading frame for a polyprotein of 2583 amino acids. Sequence comparison and phylogenic analysis suggest that P313/75 is most closely related to the prototype equine rhinitis B virus (ERBV) strain P1436/71, formerly named equine rhinovirus type 2. A high degree of sequence similarity was found in the P2 and P3 regions...
Breed demarcation and potential for breed allocation of horses assessed by microsatellite markers.
Animal genetics    June 26, 2001   Volume 32, Issue 2 59-65 doi: 10.1046/j.1365-2052.2001.00705.x
Bjørnstad G, Røed KH.Population demarcation of eight horse breeds was investigated using genotype information of 306 horses from 26 microsatellite loci. The breeds include the indigenous Norwegian breeds Fjord Horse, Nordland/Lyngen Horse, Døle Horse and Coldblooded Trotter together with Icelandic Horse, Shetland Pony, Standardbred and Thoroughbred. Both phylogenetic analysis and a maximum likelihood method were applied to examine the potential for breed allocation of individual animals. The phylogenetic analysis utilizing simple allele sharing statistics revealed clear demarcation among the breeds; 95% of the in...
Phylogenetic characterisation of the G(L) sequences of equine arteritis virus isolated from semen of asymptomatic stallions and fatal cases of equine viral arteritis in Denmark.
Veterinary microbiology    May 12, 2001   Volume 80, Issue 4 339-346 doi: 10.1016/s0378-1135(01)00323-6
Larsen LE, Storgaard T, Holm E.The study describes for the first time the phylogenetic relationship between equine arteritis virus (EAV) isolated from asymptomatic virus-shedding stallions and fatal cases of equine viral arteritis (EVA) in an European country. EAV was isolated from three dead foals and an aborted foetus during three different outbreaks of EVA. From these fatalities, the complete open reading frame 5, encoding the EAV G(L) protein, was amplified by reverse transcription-polymerase chain reaction and subjected to nucleotide sequence analysis. Furthermore, DNA sequences were obtained from virus isolated from s...
Phylogenetic analysis of partial mitochondrial cytochrome oxidase c subunit I and large ribosomal RNA sequences and nuclear internal transcribed spacer I sequences from species of Cyathostominae and Strongylinae (Nematoda, Order Strongylida), parasites of the horse.
Parasitology    January 13, 2001   Volume 121 Pt 6 649-659 doi: 10.1017/s003118200000696x
McDonnell A, Love S, Tait A, Lichtenfels JR, Matthews JB.Three nucleotide data sets, one nuclear (ITS-2) and two mitochondrial (COI and l-rRNA), have been investigated in order to determine relationships among species of Strongylinae and Cyathostominae, intestinal parasites of the horse. The data exhibited a strong mutational bias towards A and T and in the COI gene, silent sites appeared to saturate rapidly partly due to this substitution bias. Thus, the COI gene was found to be less phylogenetically informative than the l-rRNA and ITS-2 genes. Combined analysis of the l-rRNA and ITS-2 genes supported a monophyletic clade of the cyathostomes with T...
Secondary structure model for the ITS-2 precursor rRNA of strongyloid nematodes of equids: implications for phylogenetic inference.
International journal for parasitology    August 29, 2000   Volume 29, Issue 12 1949-1964 doi: 10.1016/s0020-7519(99)00155-1
Hung GC, Chilton NB, Beveridge I, Gasser RB.In order to maximise the positional homology in the primary sequence alignment of the second internal transcribed spacer for 30 species of equine strongyloid nematodes, the secondary structures of the precursor ribosomal RNA were predicted using an approach combining an energy minimisation method and comparative sequence analysis. The results indicated that a common secondary structure model of the second internal transcribed spacer of these nematodes was maintained despite significant interspecific differences (2-56%) in primary sequences. The secondary structure model was then used to refine...
A molecular systematic framework for equine strongyles based on ribosomal DNA sequence data.
International journal for parasitology    February 17, 2000   Volume 30, Issue 1 95-103 doi: 10.1016/s0020-7519(99)00166-6
Hung GC, Chilton NB, Beveridge I, Gasser RB.In this study, molecular data sets were used to address the controversies relating to the systematics of strongyloid nematodes of equids utilising morphological data sets. DNA sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of ribosomal DNA were determined for 30 species of equine strongyles and the systematic relationships reconstructed using phenetic and phylogenetic tree-building methods. The molecular data provided support for the hypothesis that the genera with large subglobular buccal capsules are ancestral to those with small cylindrical buccal capsules,...