To elucidate the systematic status of the enigmatic saola (Pseudoryx nghetinhensis), a new bovid genus recently discovered in Vietnam, and to investigate phylogenetic relationships within the family Bovidae, four distinct DNA markers were sequenced. Complete mitochondrial cytochrome b (1143 bp) and 12S rRNA (956 bp) genes and non-coding regions from the nuclear genes for aromatase cytochrome P-450 (199 bp) and lactoferrin (338 bp) have been compared for 25 bovid species and three Cervidae and Antilocapridae outgroups. Independent and/or combined analyses of the four nucleotide matrices through maximum parsimony and maximum-likelihood methods indicated that Bovidae consists of two major lineages, i.e. Bovinac which contains the tribes Bovini, Boselaphini and Tragelaphini, and Antilopinae which encompasses all other bovids. Within Bovinae, the tribe Bovini is divided into buffalo Bovini (Bubalus and Syncerus) and cattle Bovini (Bos and Bison) and Tragelaphini are possibly related to Boselaphini. Pseudoryx is shown to be (i) robustly nested within Bovinae; (ii) strongly associated with Bovini; and (iii) tentatively sharing a sister-group relationship with cattle Bovini. Within Antilopinae, three robust clades are in evidence: (i) Hippotragus and Damaliscus are linked to Ovis; (ii) Aepyceros joins Neotragus; and (iii) Cephalophus clusters with Oreotragus.
The tribe Bovini contains a number of commercially and culturally important species, such as cattle. Understanding their evolutionary time scale is important for distinguishing between post-glacial and domestication-associated population expansions, but estimates of bovine divergence times have been hindered by a lack of reliable calibration points. We present a Bayesian phylogenetic analysis of 481 mitochondrial D-loop sequences, including 228 radiocarbon-dated ancient DNA sequences, using a multi-demographic coalescent model. By employing the radiocarbon dates as internal calibrations, we co-estimate the bovine phylogeny and divergence times in a relaxed-clock framework. The analysis yields evidence for significant population expansions in both taurine and zebu cattle, European aurochs and yak clades. The divergence age estimates support domestication-associated expansion times (less than 12 kyr) for the major haplogroups of cattle. We compare the molecular and palaeontological estimates for the Bison–Bos divergence.
divergence times; demographic model; population expansion; ancient DNA; time dependency
Identifying recent positive selection signatures in domesticated animals could provide information on genome response to strong directional selection from domestication and artificial selection. With the completion of the cattle genome, private companies are now providing large numbers of polymorphic markers for probing variation in domestic cattle (Bos taurus). We analysed over 7,500 polymorphic single nucleotide polymorphisms (SNP) in beef (Angus) and dairy (Holstein) cattle and outgroup species Bison, Yak and Banteng in an indirect test of inbreeding and positive selection in Domestic cattle.
Outgroup species: Bison, Yak and Banteng, were genotyped with high levels of success (90%) and used to determine ancestral and derived allele states in domestic cattle. Frequency spectrums of the derived alleles in Angus and Holstein were examined using Fay and Wu's H test. Significant divergences from the predicted frequency spectrums expected under neutrality were identified. This appeared to be the result of combined influences of positive selection, inbreeding and ascertainment bias for moderately frequent SNP. Approximately 10% of all polymorphisms identified as segregating in B. taurus were also segregating in Bison, Yak or Banteng; highlighting a large number of polymorphisms that are ancient in origin.
These results suggest that a large effective population size (Ne) of approximately 90,000 or more existed in B. taurus since they shared a common ancestor with Bison, Yak and Banteng ~1–2 million years ago (MYA). More recently Ne decreased sharply probably associated with domestication. This may partially explain the paradox of high levels of polymorphism in Domestic cattle and the relatively small recent Ne in this species. The period of inbreeding caused Fay and Wu's H statistic to depart from its expectation under neutrality mimicking the effect of selection. However, there was also evidence for selection, because high frequency derived alleles tended to cluster near each other on the genome.
It has been established that mammalian egg zona pellucida (ZP) glycoproteins are responsible for species-restricted binding of sperm to unfertilized eggs, inducing the sperm acrosome reaction, and preventing polyspermy. In mammals, ZP apparently represents a barrier to heterospecific fertilization and thus probably contributes to reproductive isolation between species. The evolutionary relationships between some members of the tribe Bovini are complex and highly debatable, particularly, those involving Bos and Bison species for which interspecific hybridization is extensively documented. Because reproductive isolation is known to be a major precursor of species divergence, testing evolutionary patterns of ZP glycoproteins may shed some light into the speciation process of these species. To this end, we have examined intraspecific and interspecific genetic variation of two ZP genes (Zp2 and Zp3) for seven representative species (111 individuals) from the Bovini tribe, including five species from Bos and Bison, and two species each from genera Bubalus and Syncerus.
A pattern of low levels of intraspecific polymorphism and interspecific divergence was detected for the two sequenced fragments each for Zp2 and Zp3. At intraspecific level, none of neutrality tests detected deviations from neutral equilibrium expectations for the two genes. Several haplotypes in both genes were shared by multiple species from Bos and Bison.
Here we argue that neither ancestral polymorphism nor introgressive hybridization alone can fully account for haplotype sharing among species from Bos and Bison, and that both scenarios have contributed to such a pattern of haplotype sharing observed here. Additionally, codon-based tests revealed strong evidence for purifying selection in the Zp3 coding haplotype sequences and weak evidence for purifying selection in the Zp2 coding haplotype sequences. Contrary to a general genetic pattern that genes or genomic regions contributing to reproductive isolation between species often evolve rapidly and show little or no gene flow between species, these results demonstrate that, particularly, those sequenced exons of the Zp2 and the Zp3 did not show any contribution to reproductive isolation between the bovine species studied here.
The kouprey is a rare and enigmatic forest ox discovered by scientists in Cambodia only in 1937. Numerous morphological hypotheses have been proposed for the origin of the kouprey: that it is a species closely related to banteng and gaur, two other wild oxen of southeast Asia; a morphologically divergent species placed in a separate genus, named Novibos; a wild species linked to aurochs and domestic cattle; a vicariant population of banteng; a feral cattle; or a hybrid of banteng with either zebu cattle, gaur or water buffalo.
In a recent paper, which gained a lot of media coverage, Galbreath et al. analysed mitochondrial DNA sequences and concluded that the kouprey never existed as a wild, natural species, and that it was a feral hybrid between banteng and zebu cattle.
Here we analyse eight DNA markers—three mitochondrial regions and five nuclear fragments—representing an alignment of 4582 nucleotides for the holotype of the kouprey and all related species. Our results demonstrate that the kouprey is a real and naturally occurring species, and show that Cambodian populations of banteng acquired a mitochondrial genome of kouprey by natural introgressive hybridization during the Pleistocene epoch.
kouprey; Bos sauveli; Bos javanicus; introgression; hybridization; conservation
If mutation within the coding region of the genome is largely not adaptive, the ratio of nonsynonymous (dN) to synonymous substitutions (dS) per site (dN/dS) should be approximately equal among closely related species. Furthermore, dN/dS in divergence between species should be equivalent to dN/dS in polymorphisms. This hypothesis is of particular interest in closely related members of the Bovini tribe, because domestication has promoted rapid phenotypic divergence through strong artificial selection of some species while others remain undomesticated. We examined a number of genes that may be involved in milk production in Domestic cattle and a number of their wild relatives for evidence that domestication had affected molecular evolution. Elevated rates of dN/dS were further queried to determine if they were the result of positive selection, low effective population size (Ne) or reduced selective constraint.
We have found that the domestication process has contributed to higher dN/dS ratios in cattle, especially in the lineages leading to the Domestic cow (Bos taurus) and Mithan (Bos frontalis) and within some breeds of Domestic cow. However, the high rates of dN/dS polymorphism within B. taurus when compared to species divergence suggest that positive selection has not elevated evolutionary rates in these genes. Likewise, the low rate of dN/dS in Bison, which has undergone a recent population bottleneck, indicates a reduction in population size alone is not responsible for these observations.
The effect of selection depends on effective population size and the selection coefficient (Nes). Typically under domestication both selection pressure for traits important in fitness in the wild and Ne are reduced. Therefore, reduced selective constraint could be responsible for the observed elevated evolutionary ratios in domesticated species, especially in B. taurus and B. frontalis, which have the highest dN/dS in the Bovini. This may have important implications for tests of selection such as the McDonald-Kreitman test. Surprisingly we have also detected a significant difference in the supposed neutral substitution rate between synonymous and noncoding sites in the Bovine genome, with a 30% higher rate of substitution at synonymous sites. This is due, at least in part, to an excess of the highly mutable CpG dinucleotides at synonymous sites, which will have implications for time of divergence estimates from molecular data.
The domestication of plants and animals was extremely important anthropologically. Previous studies have revealed a general tendency for populations of livestock species to include deeply divergent maternal lineages, indicating that they were domesticated in multiple, independent events from genetically discrete wild populations. However, in water buffalo, there are suggestions that a similar deep maternal bifurcation may have originated from a single population. These hypotheses have rarely been rigorously tested because of a lack of sufficient wild samples. To investigate the origin of the domestic yak (Poephagus grunnies), we analyzed 637 bp of maternal inherited mtDNA from 13 wild yaks (including eight wild yaks from a small population in west Qinghai) and 250 domesticated yaks from major herding regions.
The domestic yak populations had two deeply divergent phylogenetic groups with a divergence time of > 100,000 yrs BP. We here show that haplotypes clustering with two deeply divergent maternal lineages in domesticated yaks occur in a single, small, wild population. This finding suggests that all domestic yaks are derived from a single wild gene pool. However, there is no clear correlation of the mtDNA phylogenetic clades and the 10 morphological types of sampled yaks indicating that the latter diversified recently. Relatively high diversity was found in Qinghai and Tibet around the current wild distribution, in accordance with previous suggestions that the earliest domestications occurred in this region. Conventional molecular clock estimation led to an unrealistic early dating of the start of the domestication. However, Bayesian estimation of the coalescence time allowing a relaxation of the mutation rate are better in agreement with a domestication during the Holocene as supported by archeological records.
The information gathered here and the previous studies of other animals show that the demographic histories of domestication of livestock species were highly diverse despite the common general feature of deeply divergent maternal lineages. The results further suggest that domestication of local wild prey ungulate animals was a common occurrence during the development of human civilization following the postglacial colonization in different locations of the world, including the high, arid Qinghai-Tibetan Plateau.
Harpalinae is a large, monophyletic subfamily of carabid ground beetles containing more than 19,000 species in approximately 40 tribes. The higher level phylogenetic relationships within harpalines were investigated based on nucleotide data from two nuclear genes, wingless and 28S rDNA. Phylogenetic analyses of combined data indicate that many harpaline tribes are monophyletic, however the reconstructed trees showed little support for deeper nodes. In addition, our results suggest that the Lebiomorph Assemblage (tribes Lebiini, Cyclosomini, Graphipterini, Perigonini, Odacanthini, Lachnophorini, Pentagonicini, Catapiesini and Calophaenini), which is united by a morphological synapomorphy, is not monophyletic, and the tribe Lebiini is paraphyletic with respect to members of Cyclosomini. Two unexpected clades of tribes were supported: the Zuphiitae, comprised of Anthiini, Zuphiini, Helluonini, Dryptini, Galeritini, and Physocrotaphini; and a clade comprised of Orthogoniini, Pseudomorphini, and Graphipterini. The data presented in this study represent a dense sample of taxa to examine the molecular phylogeny of Harpalinae and provide a useful framework to examine the origin and evolution of morphological and ecological diversity in this group.
beetle systematics; ground beetles; large subunit ribosomal DNA; lebiomorph; nuclear genes; wingless
Pregnancy-Associated Glycoproteins (PAGs) are trophoblastic proteins belonging to the Aspartic proteinase family secreted by different placental cells of many mammalian species. They play a pivotal role in placentogenesis, foetomaternal unit remodeling, and implantation. The identification of the genes encoding those proteins will be helpful to unravel the intricate embryogenomic functions during pregnancy establishment. Considering importance of these proteins, the present study was undertaken to characterize the pregnancy associated glycoprotein-1 gene of buffalo. An 1181 base pairs buffalo Pregnancy-Associated Glycoprotein PAG-1 gene was PCR amplified from the RNA obtained from the fetal cotyledons. BLAST analysis of the buffalo PAG-1 sequence retrieved a total of 20 cattle, 5 goat, and 4 sheep PAG sequences, exhibiting more than 80% similarity. Buffalo PAG-1 gene contained an uninterrupted open reading frame of 1140 base pairs encoding 380 amino acids that possess a 15 amino acid signal peptide and mature peptide of 365 amino acids. The phylogenetic study of the buffalo PAG-1 gene revealed buffalo PAG-1 is more related to cattle, goat, and sheep PAG-1 sequences. By this study characterization of buffalo PAG-1 gene and its evolutionary relationship was deduced for the first time.
In the present study, water buffalo MHC (Bubu)-DRB cDNA was cloned and characterized. The 1022 base long-amplified cDNA product encompassed a single open reading frame of 801 bases that coded for 266 amino acids. The Bubu-DRB sequence showed maximum homology with the BoLA-DRB3*0101 allele of cattle. A total of seven amino acid residues were found to be unique for the Bubu-DRB sequence. The majority of amino acid substitutions was observed in the β1 domain. Residues associated with important functions were mostly conserved. Water buffalo DRB was phylogenetically closer to goat DRB*A.
water buffalo; cDNA; DRB; MHC; phylogeny
The braconid subfamily Rogadinae is a large, cosmopolitan group of endoparasitoid wasps characterised by 'mummifying' their lepidopteran host larvae, from which the adult subsequently emerges. Rogadines attack a variety of both macro- and microlepidopteran taxa, although the speciose genus Aleiodes almost exclusively attacks macrolepidopterans. Here, we investigate the phylogenetic history of the Rogadinae, revise their higher-level classification and assess the evolution of their host ranges and mummy types. We also assess the divergence times within the subfamily and discuss the reasons for the extraordinary evolutionary diversification of Aleiodes.
Our Bayesian analyses weakly support the monophyly of the subfamily. A clade comprising all Aleiodes species and some other taxa is not nested within the tribe Rogadini as previously supposed, but instead is recovered as sister to the Yeliconini, with the remaining Rogadini genera being recovered as sister to the Stiropiini. The Rogadinae is estimated to have originated during the mid to late Eocene, 36.1–51.62 MYA. Molecular dating gives a more recent origin for the Aleiodes clade (17.98–41.76 MYA) compared to the origins proposed for two of its principal lepidopteran host groups (Noctuidae: 60.7–113.4 MYA; Geometridae 48–62 MYA). The Bayesian ancestral reconstruction of the emergence habits from the mummified hosts weakly recovered an anterior emergence as the ancestral condition for the subfamily. Producing a hard mummy has evolved at various times independently, though most of the species with this biology belong to the Aleiodes clade.
Based on our results, we erect the tribe Aleiodini nov. to include Aleiodes and Heterogamus stat. rev. Cordylorhogas, Pholichora and Hemigyroneuron are synonymised with Aleiodes. The molecular dating of clades and the ancestral reconstruction of host ranges support the hypothesis that radiation within Aleiodes s. s. was due to host recruitment leading to host range expansion followed by speciation, and not to parasitoid-host coevolution. Within the Rogadinae, variation in the site of emergence from the mummified host probably evolved as a consequence of the mummy's site and mode of formation, and the extent of mummy tanning/hardness to the degree of protection needed in relation to the cost of providing it.
Prolactin receptor (PRLR) and growth hormone receptor (GHR) belong to the large superfamily of class 1 cytokine receptors. Both of them have been identified as candidate genes affecting key quantitative traits, like growth and reproduction in livestock. We have previously studied the molecular anatomy of the cytoplasmic domain of GHR in different cattle breeds and artiodactyl species. In this study we have analysed the corresponding cytoplasmic signalling region of PRLR.
We sequenced PRLR gene exon 10, coding for the major part of the cytoplasmic domain, from cattle, American bison, European bison, yak, sheep, pig and wild boar individuals. We found different patterns of variation in the two receptors within and between ruminants and pigs. Pigs and bison species have no variation within GHR exon 10, but show high haplotype diversity for the PRLR exon 10. In cattle, PRLR shows lower diversity than GHR. The Bovinae PRLR haplotype network fits better the known phylogenetic relationships between the species than that of the GHR, where differences within cattle breeds are larger than between the different species in the subfamily. By comparison with the wild boar haplotypes, a high number of subsequent nonsynonymous substitutions seem to have accumulated in the pig PRLR exon 10 after domestication.
Both genes affect a multitude of traits that have been targets of selection after domestication. The genes seem to have responded differently to different selection pressures imposed by human artificial selection. The results suggest possible effects of selective sweeps in GHR before domestication in the pig lineage or species divergence in the Bison lineage. The PRLR results may be explained by strong directional selection in pigs or functional switching.
As the campaign to eradicate bovine brucellosis (Brucella abortus) and tuberculosis (Mycobacterium bovis) in Canadian livestock nears completion, the importance of extraneous sources of these diseases increases. This review summarizes the literature on brucellosis and tuberculosis in Canadian wildlife species to determine existing and potential hosts. Canadian caribou (Rangifer tarandus) are reservoirs of Brucella suis biotype 4 which is pathogenic in caribou, humans and muskoxen but reportedly nonpathogenic in livestock. Bison (Bison bison) and elk (Cervus canadensis) are significant reservoirs of B abortus and M. bovis. The bison in and around Wood Buffalo National Park have both diseases and are the only wildlife reservoir in Canada. Free-ranging elk are important reservoirs of brucellosis in Wyoming, and captive elk initiated the recent outbreak of bovine tuberculosis in 20 American states which has also involved bison and cattle herds. If bison and elk ranching continues to develop in Canada, the industry will have to be monitored to prevent the introduction and spread of infectious diseases like brucellosis and tuberculosis. This requires the evaluation and / or development of effective diagnostic methods for use in these animals.
Wildlife; brucellosis; tuberculosis; Canada; disease control
Guenons (tribe Cercopithecini) are a species-rich group of primates that have attracted considerable attention from both primatologists and evolutionary biologists. The complex speciation pattern has made the elucidation of their relationships a challenging task, and many questions remain unanswered. SINEs are a class of non-autonomous mobile elements and are essentially homoplasy-free characters with known ancestral states, making them useful genetic markers for phylogenetic studies.
We identified 151 novel Alu insertion loci from 11 species of tribe Cercopithecini, and used these insertions and 17 previously reported loci to infer a phylogenetic tree of the tribe Cercopithecini. Our results robustly supported the following relationships: (i) Allenopithecus is the basal lineage within the tribe; (ii) Cercopithecus lhoesti (L'Hoest's monkey) forms a clade with Chlorocebus aethiops (African green monkey) and Erythrocebus patas (patas monkey), supporting a single arboreal to terrestrial transition within the tribe; (iii) all of the Cercopithecus except C. lhoesti form a monophyletic group; and (iv) contrary to the common belief that Miopithecus is one of the most basal lineages in the tribe, M. talapoin (talapoin) forms a clade with arboreal members of Cercopithecus, and the terrestrial group (C. lhoesti, Chlorocebus aethiops and E. patas) diverged from this clade after the divergence of Allenopithecus. Some incongruent loci were found among the relationships within the arboreal Cercopithecus group. Several factors, including incomplete lineage sorting, concurrent polymorphism and hybridization between species may have contributed to the incongruence.
This study presents one of the most robust phylogenetic hypotheses for the tribe Cercopithecini and demonstrates the advantages of SINE insertions for phylogenetic studies.
The water buffalo is vital to the lives of small farmers and to the economy of many countries worldwide. Not only are they draught animals, but they are also a source of meat, horns, skin and particularly the rich and precious milk that may be converted to creams, butter, yogurt and many cheeses. Genome analysis of water buffalo has advanced significantly in recent years. This review focuses on currently available genome resources in water buffalo in terms of cytogenetic characterization, whole genome mapping and next generation sequencing. No doubt, these resources indicate that genome science comes of age in the species and will provide knowledge and technologies to help optimize production potential, reproduction efficiency, product quality, nutritional value and resistance to diseases. As water buffalo and domestic cattle, both members of the Bovidae family, are closely related, the vast amount of cattle genetic/genomic resources might serve as shortcuts for the buffalo community to further advance genome science and biotechnologies in the species.
Water buffalo; Genome resources; Cytogenetics; Whole genome mapping; next generation sequencing; Genome biotechnology.
Background and Aims
The water gap is an important morphoanatomical structure in seeds with physical dormancy (PY). It is an environmental signal detector for dormancy break and the route of water into the non-dormant seed. The Convolvulaceae, which consists of subfamilies Convolvuloideae (11 tribes) and Humbertoideae (one tribe, monotypic Humberteae), is the only family in the asterid clade known to produce seeds with PY. The primary aim of this study was to compare the morphoanatomical characteristics of the water gap in seeds of species in the 11 tribes of the Convolvuloideae and to use this information, and that on seed dormancy and storage behaviour, to construct a phylogenetic tree of seed dormancy for the subfamily.
Scanning electron microscopy (SEM) was used to define morphological changes in the hilum area during dormancy break; hand and vibratome sections were taken to describe the anatomy of the water gap, hilum and seed coat; and dye tracking was used to identify the initial route of water entry into the non-dormant seed. Results were compared with a recent cladogram of the family.
Species in nine tribes have (a) layer(s) of palisade cells in the seed coat, a water gap and orthodox storage behaviour. Erycibe (Erycibeae) and Maripa (Maripeae) do not have a palisade layer in the seed coat or a water gap, and are recalcitrant. The hilar fissure is the water gap in relatively basal Cuscuteae, and bulges adjacent to the micropyle serve as the water gap in the Convolvuloideae, Dicranostyloideae (except Maripeae) and the Cardiochlamyeae clades. Seeds from the Convolvuloideae have morphologically prominent bulges demarcated by cell shape in the sclereid layer, whereas the Dicranostyloideae and Cardiochlamyeae have non-prominent bulges demarcated by the number of sub-cell layers. The anatomy and morphology of the hilar pad follow the same pattern.
PY in the subfamily Convolvuloideae probably evolved in the aseasonal tropics from an ancestor with recalcitrant non-dormant seeds, and it may have arisen as Convolvulaceae radiated to occupy the seasonal tropics. Combinational dormancy may have developed in seeds of some Cuscuta spp. as this genus moved into temperate habitats.
Convolvulaceae; evolution; hilar fissure; physical dormancy; water gap
A yeast causing widespread infection of laboratory mice was identified from 26S rRNA gene sequences as Candida pintolopesii. To determine the relationship of C. pintolopesii with other members of the Kazachstania (Arxiozyma) telluris species complex, nucleotide sequences from domains 1 and 2 of the 26S rRNA gene, the mitochondrial small-subunit rRNA gene, and the RNA polymerase II gene were phylogenetically analyzed. That analysis resolved the 48 strains examined into five closely related species: K. telluris, Candida bovina, C. pintolopesii, Candida slooffiae, and a previously unknown species. One or more strains of each of the last four species formed an ascosporic state much like that of K. telluris. To place these ascosporogenous strains taxonomically, it is proposed that they be assigned to the teleomorphic genus Kazachstania as K. bovina (type strain NRRL Y-7283, CBS 9732, from the nasal passage of a pigeon), K. heterogenica (type strain NRRL Y-27499, CBS 2675, from rodent feces), K. pintolopesii (type strain NRRL Y-27500, CBS 2985, from the peritoneal fluid of a dead guinea pig), and K. slooffiae (type strain NRRL YB-4349, CBS 9733, from the cecum of a horse). On the basis of multigene sequence analyses, K. heterogenica appears to be a hybrid of K. pintolopesii and a presently unknown species. With the exception of K. bovina, the phylogenetically defined species show a moderate degree of host specificity.
The entire mitochondrial cytochrome b (cyt b) gene was compared for 11 species of the artiodactyl family Cervidae, representing all living subfamilies, i.e., the antlered Cervinae (Cervus elaphus, C. nippon, Dama dama), Muntiacinae (Muntiacus reevesi), and Odocoileinae (Odocoileus hemionus, Mazama sp., Capreolus capreolus, C. pygargus, Rangifer tarandus, Alces alces); and the antlerless Hydropotinae (Hydropotes inermis). Phylogenetic analyses using Tragulidae, Antilocapridae, Giraffidae and Bovidae as outgroups provide evidence for three multifurcating principal clades within the monophyletic family Cervidae. First, Cervinae and Muntiacus are joined in a moderately-to-strongly supported clade of Eurasian species. Second, Old World Odocoileinae (Capreolus and Hydropotes) associate with the Holarctic Alces. Third, New World Odocoileinae (Mazama and Odocoileus) cluster with the Holarctic Rangifer. The combination of mitochondrial cyt b and nuclear k-casein sequences increases the robustness of these three clades. The Odocoileini + Rangiferini clade is unambiguously supported by a unique derived cranial feature, the expansion of the vomer which divides the choana. Contrasting with current taxonomy, Hydropotes is not the sister group of all the antlered deers, but it is nested within the Odocoileinae. Therefore, Hydropotes lost the antlers secondarily. Thus, the mitochondrial cyt b phylogeny splits Cervidae according to plesiometacarpal (Cervinae + Muntiacinae) versus telemetacarpal (Odocoileinae + Hydropotinae) conditions, and suggests paraphyly of antlered deer.
Quantitative trait loci (QTL) studies have indicated growth hormone receptor (GHR) as a candidate gene affecting cattle milk yield and composition. In order to characterize genetic variation at GHR in cattle, we studied European and East African breeds with different histories of selection, and Bos grunniens, Ovis aries, Sus scrofa, Bison bison and Rangifer tarandus as references. We sequenced most of the cytoplasmic domain (900 bp of exon 10), 89 bp of exon 8, including the putative causative mutation for the QTL effect, and 390 bp of intron 8 for comparison. In the cytoplasmic domain, seven synonymous and seven non-synonymous single nucleotide polymorphisms (SNP) were identified in cattle. Three non-synonymous SNPs were found in sheep and one synonymous SNP in yak, while other studied species were monomorphic. Three major haplotypes were observed, one unique to African breeds, one unique to European breeds and one shared. Bison and yak haplotypes are derivatives of the European haplotype lineage. Most of the exon 10 non-synonymous cattle SNPs appear at phylogenetically highly conserved sites. The polymorphisms in exon 10 cluster around a ruminant-specific tyrosine residue, suggesting that this site may act as an additional signalling domain of GHR in ruminants. Alternative explanations for the persistent polymorphism include balancing selection, hitch-hiking, pleiotropic or sexually antagonistic fitness effects or relaxed functional constraints.
growth hormone receptor; cattle; polymorphism; genetic variation; QTL; quantitative trait locus; GHR; growth hormone receptor; GH; growth hormone; SNP; single nucleotide polymorphism
Background and Aims
The angiosperm family Myrtaceae comprises 17 tribes with more than half of the estimated 5500 species being referred to the fleshy-fruited and predominantly rainforest associated Syzygieae and Myrteae. Previous studies suggest that fleshy fruits have evolved separately in these lineages, whereas generally shifts in fruit morphology have been variously implicated in diversification rate shifts among angiosperms. A phylogenetic hypothesis and estimate divergence times for Myrtaceae is developed as a basis to explore the evidence for, and drivers of, elevated diversification rates among the fleshy-fruited tribes of Myrtaceae.
Bayesian phylogenetic analyses of plastid and nuclear DNA sequences were used to estimate intertribal relationships and lineage divergence times in Myrtaceae. Focusing on the fleshy-fruited tribes, a variety of statistical approaches were used to assess diversification rates and diversification rate shifts across the family.
Analyses of the sequence data provide a strongly supported phylogenetic hypothesis for Myrtaceae. Relative to previous studies, substantially younger ages for many of the clades are reported, and it is argued that the use of flexible calibrations to incorporate fossil data provides more realistic divergence estimates than the use of errorless point calibrations. It is found that Syzygieae and Myrteae have experienced elevated diversification rates relative to other lineages of Myrtaceae. Positive shifts in diversification rate have occurred separately in each lineage, associated with a shift from dry to fleshy fruit.
Fleshy fruits have evolved independently in Syzygieae and Myrteae, and this is accompanied by exceptional diversification rate shifts in both instances, suggesting that the evolution of fleshy fruits is a key innovation for rainforest Myrtaceae. Noting the scale dependency of this hypothesis, more complex explanations may be required to explain diversification rate shifts occurring within the fleshy-fruited tribes, and the suggested phylogenetic hypothesis provides an appropriate framework for this undertaking.
Myrtaceae; Myrtoideae; Myrteae; Syzygieae; phylogeny; molecular dating; speciation; diversification rates
The involvement of veterinarians in the health management of North American bison will continue to increase, particularly in regard to the development of the bison ranching industry. More intensive management of bison will lead to greater recognition of diseases, and will raise concerns about the transmission of diseases between bison and other livestock species. This review of the infectious and noninfectious diseases of free-ranging and captive bison populations indicates that bison are susceptible to a wide range of indigenous and foreign diseases that occur in cattle and other livestock species. Most of the available information is based on necropsy results or serological surveys, and there is much less information on clinical, diagnostic and preventive medicine, or on the evaluation of conventional diagnostic tests, therapeutic regimens, or vaccines in bison.
In mammals, testis determination is under the control of the sex-determining gene SRY. This Y-linked gene encodes a protein with a DNA binding domain similar to those found in high-mobility-group proteins. Here we report the cloning and sequences of the SRY genes of yak and Chinese native cattle. Our data show that SRY genes in Bovidae are less divergent, especially in the coding and 3' regions.
sex determination; SRY; evolution; Bovidae
Recent phylogeographic studies of the endangered Asian elephant (Elephas maximus) reveal two highly divergent mitochondrial DNA (mtDNA) lineages, an elucidation of which is central to understanding the species's evolution. Previous explanations for the divergent clades include introgression of mtDNA haplotypes between ancestral species, allopatric divergence of the clades between Sri Lanka or the Sunda region and the mainland, historical trade of elephants, and retention of divergent lineages due to large population sizes. However, these studies lacked data from India and Myanmar, which host approximately 70 per cent of all extant Asian elephants. In this paper, we analyse mtDNA sequence data from 534 Asian elephants across the species's range to explain the current distribution of the two divergent clades. Based on phylogenetic reconstructions, estimates of times of origin of clades, probable ancestral areas of origin inferred from dispersal–vicariance analyses and the available fossil record, we believe both clades originated from Elephas hysudricus. This probably occurred allopatrically in different glacial refugia, the α clade in the Myanmar region and the β clade possibly in southern India–Sri Lanka, 1.6–2.1 Myr ago. Results from nested clade and dispersal–vicariance analyses indicate a subsequent isolation and independent diversification of the β clade in both Sri Lanka and the Sunda region, followed by northward expansion of the clade. We also find more recent population expansions in both clades based on mismatch distributions. We therefore suggest a contraction–expansion scenario during severe climatic oscillations of the Quaternary, with range expansions from different refugia during warmer interglacials leading to the varying geographical overlaps of the two mtDNA clades. We also demonstrate that trade in Asian elephants has not substantially altered the species's mtDNA population genetic structure.
phylogeography; divergent mitochondrial clades; Pleistocene refugia; elephant trade; Elephas fossils
Cave organisms have been used as models for evolution and biogeography, as their reduced above-ground dispersal produces phylogenetic patterns of area distribution that largely match the geological history of mountain ranges and cave habitats. Most current hypotheses assume that subterranean lineages arose recently from surface dwelling, dispersive close relatives, but for terrestrial organisms there is scant phylogenetic evidence to support this view. We study here with molecular methods the evolutionary history of a highly diverse assemblage of subterranean beetles in the tribe Leptodirini (Coleoptera, Leiodidae, Cholevinae) in the mountain systems of the Western Mediterranean.
Ca. 3.5 KB of sequence information from five mitochondrial and two nuclear gene fragments was obtained for 57 species of Leptodirini and eight outgroups. Phylogenetic analysis was robust to changes in alignment and reconstruction method and revealed strongly supported clades, each of them restricted to a major mountain system in the Iberian peninsula. A molecular clock calibration of the tree using the separation of the Sardinian microplate (at 33 MY) established a rate of 2.0% divergence per MY for five mitochondrial genes (4% for cox1 alone) and dated the nodes separating the main subterranean lineages before the Early Oligocene. The colonisation of the Pyrenean chain, by a lineage not closely related to those found elsewhere in the Iberian peninsula, began soon after the subterranean habitat became available in the Early Oligocene, and progressed from the periphery to the centre.
Our results suggest that by the Early-Mid Oligocene the main lineages of Western Mediterranean Leptodirini had developed all modifications to the subterranean life and were already present in the main geographical areas in which they are found today. The origin of the currently recognised genera can be dated to the Late Oligocene-Miocene, and their diversification can thus be traced to Miocene ancestors fully adapted to subterranean life, with no evidence of extinct epigean, less modified lineages. The close correspondence of organismal evolution and geological record confirms them as an important study system for historical biogeography and molecular evolution.
The early phylogeny of the 137 species in the Bovidae family is difficult to resolve; knowledge of the evolution and relationships of the tribes would facilitate comparative mapping, understanding chromosomal evolution patterns and perhaps assist breeding and domestication strategies. We found that the study of the presence and organization of two repetitive DNA satellite sequences (the clone pOaKB9 from sheep, a member of the 1.714 satellite I family and the pBtKB5, a 1.715 satellite I clone from cattle) on the X and autosomal chromosomes by in situ hybridization to chromosomes from 15 species of seven tribes, was informative. The results support a consistent phylogeny, suggesting that the primitive form of the X chromosome is acrocentric, and has satellite I sequences at its centromere. Because of the distribution of the ancient satellite I sequence, the X chromosome from the extant Tragelaphini (e.g. oryx), rather than Caprini (sheep), line is most primitive. The Bovini (cow) and Tragelaphini tribes lack the 1.714 satellite present in the other tribes, and this satellite is evolutionarily younger than the 1.715 sequence, with absence of the 1.714 sequence being a marker for the Bovini and Tragelaphini tribes (the Bovinae subfamily). In the other tribes, three (Reduncini, Hippotragini and Aepycerotini) have both 1.714 and 1.715 satellite sequences present on both autosomes and the X chromosome. We suggest a parallel event in two lineages, leading to X chromosomes with the loss of 1.715 satellite from the Bovini, and the loss of both 1.714 and 1.715 satellites in a monophyletic Caprini and Alcelaphini lineage. The presence and X chromosome distribution of these satellite sequences allow the seven tribes to be distributed to four groups, which are consistent with current diversity estimates, and support one model to resolve points of separation of the tribes.
Bovidae; phylogeny; primitive X chromosome; satellite DNA