299 resultados para Ancestors
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By using 19 Y chromosome biallelic markers and 3 Y chromosome microsatellite markers, we analyzed the genetic structure of 31 indigenous Sino-Tibetan speaking populations (607 individuals) currently residing in East, Southeast, and South Asia. Our results showed that a T to C mutation at locus M122 is highly prevalent in almost all of the Sino-Tibetan populations, implying a strong genetic affinity among populations in the same language family. Furthermore, the extremely high frequency of H8, a haplotype derived from M122C, in the Sino-Tibetan speaking populations in the Himalayas including Tibet and northeast India indicated a strong bottleneck effect that occurred during a westward and then southward migration of the founding population of Tibeto-Burmans. We, therefore, postulate that the ancient people, who lived in the upper-middle Yellow River basin about 10,000 years ago and developed one of the earliest Neolithic cultures in East Asia, were the ancestors of modem Sino-Tibetan populations.
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The classification and phylogenetic relationships of the Old World monkeys are still controversial. For Asian colobines, from three to nine genera were recognized by different primatologists. In the present study, we have sequenced a 424 bp mitochondrial tRNA(Thr) gene and cytochrome b gene fragment from Macaca mulatta, Mandrillus sphinx, Mandrillus leucophaeus, Semnopithecus entellus, Trachypithecus vetulus, T. johnii, T. phayrei, T. francoisi, Pygathrix nemaeus, Rhinopithecus roxellanae, R. bieti, R. avunculus, Nasalis larvatus, and Colobus polykomos in order to gain independent information on the classification and phylogenetic relationships of those species. Phylogenetic trees were constructed with parsimony analysis by weighting transversions 5 or 10 fold greater than transitions. Our results support the following conclusions: (1) the Old World monkeys are divided into two subfamilies; (2) that among the colobines, Colobus, the African group, diverged first, and Nasalis and Rhinopithecus form a sister clade to Pygathrix; (3) that there are two clades within leaf monkeys, i.e. 1) S. entellus, T. johnii, and T. vetulus, and 2) T, phayrei and T. francoisi; (4) that Rhinopithecus avunculus, R. roxellanae, and R. bieti are closely related to each other, and they should be placed into the same subgenus; (5) that Rhinopithecus is a distinct genus; and (6) that the ancestors of Asian colobines migrated from Africa to Asia during the late Pliocene or early Pleistocene.
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Background: It is widely accepted that the ancestors of Native Americans arrived in the New World via Beringia approximately 10 to 30 thousand years ago (kya). However, the arrival time(s), number of expansion events, and migration routes into the Western
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Phylogenetic relationships of six species of Ochotona were investigated using mitochondrial DNA (mtDNA) restriction-site analysis. The phylogenetic tree constructed using PAUP was based on 62 phylogenetically informative sites with O. erythrotis designated as an outgroup. Two clades were evident. One contained O. curzoniae, O. huangensis, and O. thibetana. in the second, O. daurica was a sister taxon of O. cansus. The five species appear to come from different maternal lineages. The branching structure of the tree and sequence divergence confirm that huangensis and cansus are distinct species, and that mol-osa is a synonym of O. cansus rather than O. thibetana. Divergence time, estimated from genetic distances, indicates that the ancestors of the two maternal lineages diverged ca. 6.5 x 10(6) years ago. O. curzoniae diverged from O. huangensis, and O. daurica diverged from O. cansus, at about the same time (ca. 3.4 x 10(6) years ago). These data suggest a period of rapid radiation of the genus Ochotona in China, perhaps during the late Pliocene. These calculations correspond roughly to tectonic events and environmental changes in China throughout this period, and appear to be substantiated by the fossil record.
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The small subunit rDNA sequence of Maristentor dinoferus (Lobban, Schefter, Simpson, Pochon, Pawlowski, and Foissner, 2002) was determined and compared with sequences from other Heterotrichea and Karyorelictea. Maristentor resembles Stentor in basic morphology and had been provisionally assigned to Stentoridae. However, our phylogenetic analyses show that Maristentor is more closely related to Folliculinidae. Our results support the creation of a separate family for Maristentor, Maristentoridae n. fam., and also confirm the phylogenetic grouping of Folliculindae, Stentoridae, Blepharismidae, and Maristentoridae, which we informally call 'stentorids'. Maristentor, rather than Stentor itself, appears to be most significant in understanding the origins of folliculinids from their aloricate ancestors. Our analyses suggest continued uncertainty in the exact placement of the root of heterotrichs with this phylogenetic marker.
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The phylogenetic relationships among peritrichs remain unresolved. In this study, the complete small subunit rRNA (SSrRNA) gene sequences of seven species (Epistylis galea, Campanella umbellaria, Carchesium polypinum, Zoothamnium arbuscula, Vaginicola crystallina, Ophrydium versatile, and Opercularia microdiscum) were determined. Trees were constructed using distance-matrix, maximum-likelihood and maximum-parsimony methods, all of which strongly supported the monophyly of the subclass Peritrichia. Within the peritrichs, 1) E. galea grouped with Opercularia microdiscum and Campanella umbellaria but not the other Epistylis species, which indicates that the genus Epistylis might not be monophyletic; 2) the topological position of Carchesium and Campanella suggested that Carchesium should be placed in the family Zoothammidae, or be elevated to a higher taxonomic rank, and that Campanella should be independent of the family Epistylididae, and probably be given a new rank; and 3) Opisthonecta grouped strongly with Asty/ozoon, which suggested that Opisthonecta species were not the ancestors of the stalked peritrichs.
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Although common carp is the major fish species in Asian and European aquaculture and many domestic varieties have occurred, there is a controversy about the origination of European domestic common carp. Some scientists affirmed that the ancestor of European domestic common carp was Danube River wild common carp, but others considered it might be Asian common carp. For elucidating origination of European domestic common carp, we chose two representative European domestic common carp strains (German mirror carp and Russian scattered scaled mirror carp) and one wild common carp strain of Cyprinus carpio carpio subspecies (Volga River wild common carp) and two Asian common carp strains, the Yangtze River wild common carp (Cyprinus carpio haematopterus) and traditionally domestic Xingguo red common carp, as experimental materials. ND5-ND6 and D-loop segments of mitochondrial DNA were amplified by polymerase chain reaction and analyzed through restriction fragment length polymorphism (RFLP) and sequencing respectively. The results revealed that HaeIII and DdeI digestion patterns of ND5-ND6 segment and sequences of control region were different between European subspecies C. carpio carpio and Asian subspecies C. carpio haematopterus. Phylogenetic analysis showed that German mirror carp and Russian scattered scaled mirror carp belonged to two subspecies, C. carpio carpio and C. carpio haematopterus, respectively. Therefore, there were different ancestors for domestic carp in Europe: German mirror carp was domesticated from European subspecies C. carpio carpio and Russian scattered scaled mirror carp originated from Asian subspecies C. carpio haematopterus.
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Based on the phylogenetic and biogeographical studies of the glyptosternoid fishes in Qinghai-Tibet area, the following hypothesis is proposed: the speciation of this group has a direct relationship with the three uplift intervals of the Qinghai-Tibet Plateau. This process was explained by the theory of vicariance of biogeography. The ancestor of this group was similar to Bagarus and/or Glyptothorax, which still have a wide distribution. At the moment when the Tethys sea closed, the Indian tectonic plate collided with the Eurasian tectonic plate, so the Glyptothorax-like and Bagarus-like ancestors entered Eurasia and gradually became widely distributed. After the Pleistocene, with the enforced colliding, the gradual uplift of the Qinghai-Tibet Plateau brought about the current water environment, and the Glyptosternoids were generated from Glyptothorax-like fish under this environment. The present Glyptosternum, distributed across the Himalayas is the ancestor of Glyptosternoids. In the three uplift intervals of the plateau, the water system of this region was separated gradually and Glyptosternum-like ancestor was isolated in different rivers and evolved into various species. All this resulted in the speciation and formation of the biogeographical pattern of glyptosternoids.
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Division of labour is a marked feature of multicellular organisms. Margulis proposed that the ancestors of metazoans had only one microtubule organizing center (MTOC), so they could not move and divide simultaneously. Selection for simultaneous movement and cell division had driven the division of labour between cells. However, no evidence or explanation for this assumption was provided. Why could the unicellular ancetors not have multiple MTOCs? The gain and loss of three possible strategies are discussed. It was found that the advantage of one or two MTOC per cell is environment-dependent. Unicellular organisms with only one MTOC per cell are favored only in resource-limited environments without strong predatory pressure. If division of labour occurring in a bicellular organism just makes simultaneous movement and cell division possible, the possibility of its fixation by natural selection is very low because a somatic cell performing the function of an MTOC is obviously wasting resources. Evolutionary biologists should search for other selective forces for division of labour in cells.
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青杨组(Section Tacamahaca Spach)杨树是我国重要的乡土经济树种,目前对其分子遗传变异和系统进化的研究还很少,尤其是在青杨组杨树遗传资源极为丰富的川西地区,杨树的分子进化及亲缘关系的研究极为缺乏,非常不利于该树种遗传资源的开发和利用。本研究从川西地区收集了青杨(Populus cathayana)、青海杨(P. prezewalskii)、滇杨(P. yunnanensis)、康定杨(P. kangdingensis)、西南杨(P. schneideri)、小叶杨(P.simonii)和三脉青杨(P. trinervis)这7 个青杨组树种的10 个群体,利用多种分子标记手段对其种间的亲缘关系进行比较,并结合形态和地史资料进行了全面的研究和评价,得到了如下的主要研究结果: 1. SSR 和ISSR 位点变异丰富。通过10 对引物对50 个杨树个体的DNA 样品进行了SSR 分析,所有位点展现了丰富的群体间和种间的多态性,多态位点率达到了100%,每位点的等位基因数变化范围为5 ~ 17,平均为11.9 个;通过11 条ISSR 随机引物对供试的混合DNA 样品进行分析,共检测到130 个标记,其中多态性标记为119 个,多态百分率为91.5%。研究认为,SSR 单个标记能展现高水平信息,而ISSR 单个引物能探测更多数量多态性。通过两个标记的遗传距离、聚类图和PCA 分析,表明:同一种内不同群体间的同源性最高;康定杨和西南杨有较近的亲缘关系;小叶杨和三脉青杨聚合在一起,显示了其相互较近的亲缘关系;滇杨与其它杨树种可能存在着较远的亲缘关系。 2. 采用4 对选择性引物对7 个青杨组杨树种10 个群体进行AFLP 分析,总共扩增出284 个位点,其中200 个位点显示出了多态性,多态位点百分比为70.4%,平均多态带为50 条。TE-AFLP 的分析总共扩增出192 个位点,其中139 个位点显示出了多态性,多态位点百分比为72.4%,平均多态带为34.7 条。比较的结果表明AFLP、TE-AFLP 的遗传信息含量比较接近,略小于ISSR,大约仅为SSR 的1/3;但这两个基于AFLP 的标记系统的信息探察能力也远大于ISSR 和SSR 标记系统。这两个分子标记的聚类结果,显示小叶杨、三脉青杨和滇杨三个种聚为一组,其中小叶杨与三脉青杨的亲缘关系更近;其它几个杨树种聚为一类,西南杨与青杨表现出较近的亲缘关系。 3. 所有7 对cpSSR 引物中,仅有4 个叶绿体位点在种间具有多态性,而在种内群体中并不具有多态性,共检测出13 个条带,组合成了4 种不同的单倍型;对于cpDNA的5 对引物,共检测出了73 条酶切片段,其中52 条是多态带,组合成了9 种不同的单倍型;而5 对mtDNA 通用引物未能检测出多态性的条带,表现出线粒体的保守性。叶绿体的聚类分析认为,小叶杨、三脉青杨和滇杨有较近的母性起源,且依次聚合;其余四种杨树聚为一类,并且康定杨与西南杨表现出最近的亲缘关系,并依次与青杨和青海杨聚合。 4. 根据本文的分子数据,结合形态和生境分布资料分析认为:青杨组杨树种内群体间的遗传变异程度是小于种间的遗传差异,显示了与传统分类一致的结果;三脉青杨和小叶杨有很近的亲缘关系,可能拥有相同的祖先类群;滇杨与小叶杨和三脉青杨之间具有一定的亲缘关系,特别是在其母性祖先的起源上有着一定的同源性;西南杨与青杨和康定杨均保持着较近的亲缘关系,且有可能是这两个种原始祖先杂交后所形成的。 Although western Sichuan is regarded as a natural distribution and variation center forthe Section Tacahamaca of the Populus species in China, little is currently known about themajority of poplar species occurring in this region. In the present study, molecular data wereutilized to determine the genetic relationships among Populus species in Section Tacamahacain western Sichuan including P. cathayana, P. prezewalskii, P. yunnanensis, P. kangdingensis,P. schneideri, P. simonii and P.trinervis. The results are as fellows: 1. The genetic variation at SSR and ISSR loci was abundant. All the 10 SSR loci werepolymorphic, and the number of alleles per locus varied from 5 to 17 with a mean valueequaling 11.9. Based on the 11 ISSR primers, 130 clear and reproducible DNA fragmentswere generated, of which 119 (91.5%) were polymorphic. Our results reveal that single SSRlocus can present more genetic information, while more polymorphic bands can be detectedby single ISSR primer. Moreover, the genetic distance, cluster and PCA analysisdemonstrated that: a close relationship among accessions of the same species and suggestedmonophyly in P. przewalskii and P. cathayana; P. schneideri is genetically highly similar to P.kangdingensis; P. trinervis and P. simonii have a close genetic affinity; P. yunnanensis isdistinct from the other species. 2. Genetic relationships of poplar species in Section Tacamahaca from western Sichuanwere evaluated by means of AFLP and TE-AFLP. For four AFLP primer combinations, atotal of 284 bands were obtained of which 200 (70.4%) were polymorphic with the average of50 polymorphic bands. For four TE-AFLP primer combinations, a total of 192 band wereobtained of which 139 (72.4%) were polymorphic with the average of 34.7 polymorphicbands. Our results indicate that the genetic information of AFLP is similar to that ofTE-AFLP, and little less than that of ISSR, but only about 1/3 of that of SSR. However, theability of information detection of the two AFLP-based markers is much higher than that ofISSR and SSR. In addition, the cluster analysis of AFLP, TE-AFLP and combined data revealthat: P. yunnanensis, P. trinervis and P. simonii clustered together, and P. trinervis and P.simonii showed more closed affinity; the other four poplar species clustered together, P.cathayana and P. schneideri showed more closed origin especially. 3. The cpSSR analysis for seven Populus species belonging to the Section Tacamahaca.Four out of the seven analyzed chloroplast loci were polymorphic, whereas none of the lociwere polymorphic across the accessions within a species. 13 bands and 4 different kinds ofhaplotypes were reduced. Based on 5 pairs of cpDNA primers, 73 fragments (52 polymorphic)and 9 kinds of haplotypes were produced. However, none of the polymorphic was detected bythe 5 mtDNA primer pairs, revealing conservation of mtDNA region. The cluster analysis ofcpDNA revealed that: similar maternal phylogeny among P. yunnanensis, P. trinervis and P.simonii; the other four species clustered together, P. schneideri and P. kangdingensis showedmore closed maternal lineage especially. 4. Our molecular data, morphological characters and nature habitat revealed that: sameto the traditional taxonomy assignment, genetic variation within a same Populus species islower than that among Populus species in Section Tacamahaca; P. yunnanensis may share itschloroplast ancestor with P. trinervis and P. simonii; moreover, sister genetic relationship of P.trinervis and P. simonii indicated their similar origin; P. schneideri clustered with P.kangdingensis and P. cathayana, respectively, and may have derived from an ancienthybridization event involving the ancestors of the two species.
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How coniferous trees in northern China changed their distribution ranges in response to Quaternary climatic oscillations remains largely unknown. Here we report a study of the phylogeography of Pinus tabulaeformis, an endemic and dominant species of coniferous forest in northern China. We examined sequence variation of maternally inherited, seed-dispersed mitochondrial DNA (mtDNA) (nad5 intron 1 and nad4/3-4) and paternally inherited, pollen- and seed-dispersed chloroplast DNA (cpDNA) (rpl16 and trnS-trnG) within and among 30 natural populations across the entire range of the species. Six mitotypes and five chlorotypes were recovered among 291 trees surveyed. Population divergence was high for mtDNA variation (G(ST) = 0.738, N-ST = 0.771) indicating low levels of seed-based gene flow and significant phylogeographical structure (N-ST > G(ST), P < 0.05). The spatial distribution of mitotypes suggests that five distinct population groups exist in the species: one in the west comprising seven populations, a second with a north-central distribution comprising 15 populations, a third with a southern and easterly distribution comprising five populations, a fourth comprising one central and one western population, and a fifth comprising a single population located in the north-central part of the species' range. Each group apart from the fourth group is characterized by a distinct mitotype, with other mitotypes, if present, occurring at low frequency. It is suggested, therefore, that most members of each group apart from Group 4 are derived from ancestors that occupied different isolated refugia in a previous period of range fragmentation of the species, possibly at the time of the Last Glacial Maximum. Possible locations for these refugia are suggested. A comparison of mitotype diversity between northern and southern subgroups within the north-central group of populations (Group 2) showed much greater uniformity in the northern part of the range both within and between populations. This could indicate a northward migration of the species from a southern refugium in this region during the postglacial period, although alternative explanations cannot be ruled out. Two chlorotypes were distributed across the geographical range of the species, resulting in lower levels of among-population chlorotype variation. The geographical pattern of variation for all five chlorotypes provided some indication of the species surviving past glaciations in more than one refugium, although differentiation was much less marked, presumably due to the greater dispersal of cpDNA via pollen.
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Phylogenetic relationships of six species of Ochotona were investigated using mitochondrial DNA (mtDNA) restriction-site analysis. The phylogenetic tree constructed using PAUP was based on 62 phylogenetically informative sites with O. erythrotis designated as an outgroup. Two clades were evident. One contained O. curzoniae, O. huangensis, and O. thibetana. in the second, O. daurica was a sister taxon of O. cansus. The five species appear to come from different maternal lineages. The branching structure of the tree and sequence divergence confirm that huangensis and cansus are distinct species, and that mol-osa is a synonym of O. cansus rather than O. thibetana. Divergence time, estimated from genetic distances, indicates that the ancestors of the two maternal lineages diverged ca. 6.5 x 10(6) years ago. O. curzoniae diverged from O. huangensis, and O. daurica diverged from O. cansus, at about the same time (ca. 3.4 x 10(6) years ago). These data suggest a period of rapid radiation of the genus Ochotona in China, perhaps during the late Pliocene. These calculations correspond roughly to tectonic events and environmental changes in China throughout this period, and appear to be substantiated by the fossil record.
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Africa faces problems of ecological devastation caused by economic exploitation, rapid population growth, and poverty. Capitalism, residual colonialism, and corruption undermine Africa's efforts to forge a better future. The dissertation describes how in Africa the mounting ecological crisis has religious, political, and economic roots that enable and promote social and environmental harm. It presents the thesis that religious traditions, including their ethical expressions, can effectively address the crisis, ameliorate its impacts, and advocate for social and environmental betterment, now and in the future. First, it examines African traditional religion and Christian teaching, which together provide the foundation for African Christianity. Critical examination of both religious worldviews uncovers their complementary emphases on human responsibility toward planet Earth and future generations. Second, an analysis of the Gwembe Tonga of Chief Simamba explores the interconnectedness of all elements of the universe in African cosmologies. In Africa, an interdependent, participatory relationship exists between the world of animals, the world of humans, and the Creator. In discussing the annual lwiindi (rain calling) ceremony of Simamba, the study explores ecological overtones of African religions. Such rituals illustrate the involvement of ancestors and high gods in maintaining ecological integrity. Third, the foundation of the African morality of abundant life is explored. Across Sub-Saharan Africa, ancestors' teachings are the foundation of morality; ancestors are guardians of the land. A complementary teaching that Christ is the ecological ancestor of all life can direct ethical responses to the ecological crisis. Fourth, the eco-social implications of ubuntu (what it means to be fully human) are examined. Some aspects of ubuntu are criticized in light of economic inequalities and corruption in Africa. However, ubuntu can be transformed to advocate for eco-social liberation. Fifth, the study recognizes that in some cases conflicts exist between ecological values and religious teachings. This conflict is examined in terms of the contrast between awareness of socioeconomic problems caused by population growth, on the one hand, and advocacy of a traditional African morality of abundant children, on the other hand. A change in the latter religious view is needed since overpopulation threatens sustainable living and the future of Earth. The dissertation concludes that the identification of Jesus with African ancestors and theological recognition of Jesus as the ecological ancestor, woven together with ubuntu, an ethic of interconnectedness, should characterize African consciousness and promote resolution of the socio-ecological crisis.
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In a landmark book published in 2000, the sociologist Danièle Hervieu-Léger defined religion as a chain of memory, by which she meant that within religious communities remembered traditions are transmitted with an overpowering authority from generation to generation. After analysing Hervieu-Léger’s sociological approach as overcoming the dichotomy between substantive and functional definitions, this article compares a ritual honouring the ancestors in which a medium becomes possessed by the senior elder’s ancestor spirit among the Shona of Zimbabwe with a cleansing ritual performed by a Celtic shaman in New Hampshire, USA. In both instances, despite different social and historical contexts, appeals are made to an authoritative tradition to legitimize the rituals performed. This lends support to the claim that the authoritative transmission of a remembered tradition, by exercising an overwhelming power over communities, even if the memory of such a tradition is merely postulated, identifies the necessary and essential component for any activity to be labelled “religious”.
Gene loss, adaptive evolution and the co-evolution of plumage coloration genes with opsins in birds.
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BACKGROUND: The wide range of complex photic systems observed in birds exemplifies one of their key evolutionary adaptions, a well-developed visual system. However, genomic approaches have yet to be used to disentangle the evolutionary mechanisms that govern evolution of avian visual systems. RESULTS: We performed comparative genomic analyses across 48 avian genomes that span extant bird phylogenetic diversity to assess evolutionary changes in the 17 representatives of the opsin gene family and five plumage coloration genes. Our analyses suggest modern birds have maintained a repertoire of up to 15 opsins. Synteny analyses indicate that PARA and PARIE pineal opsins were lost, probably in conjunction with the degeneration of the parietal organ. Eleven of the 15 avian opsins evolved in a non-neutral pattern, confirming the adaptive importance of vision in birds. Visual conopsins sw1, sw2 and lw evolved under negative selection, while the dim-light RH1 photopigment diversified. The evolutionary patterns of sw1 and of violet/ultraviolet sensitivity in birds suggest that avian ancestors had violet-sensitive vision. Additionally, we demonstrate an adaptive association between the RH2 opsin and the MC1R plumage color gene, suggesting that plumage coloration has been photic mediated. At the intra-avian level we observed some unique adaptive patterns. For example, barn owl showed early signs of pseudogenization in RH2, perhaps in response to nocturnal behavior, and penguins had amino acid deletions in RH2 sites responsible for the red shift and retinal binding. These patterns in the barn owl and penguins were convergent with adaptive strategies in nocturnal and aquatic mammals, respectively. CONCLUSIONS: We conclude that birds have evolved diverse opsin adaptations through gene loss, adaptive selection and coevolution with plumage coloration, and that differentiated selective patterns at the species level suggest novel photic pressures to influence evolutionary patterns of more-recent lineages.