Odontometric systematic assessment of the Swartkrans SK 15 mandible

This study reports a comparison of molar crown and cusp size and shape in the Swartkrans early Homo mandible SK 15 with relevant Plio-Pleistocene taxa. Univariate and multivariate methods are employed to consider the morphological affinities of this specimen and to assess its taxonomy. The case exists for classifying SK 15 in Homo habilis with 11 features aligning it with this species. The results of multivariate studies are consistent with this hypothesis. Moreover, SK 15 lacks a number of important features that characterise the mandibular molars of Homo sapiens erectus. Considerable evidence for parallelism in the dental morphology of SK 15 and H. habilis with A. robustus is discussed. Fossil evidence for the presence of H. sapiens erectus during the Plio-Pleistocene of South Africa presently seems to be lacking. Archaeological interpretations should take greater account of this gap in the fossil record.     

Cladistic analysis of early Homo crania from Swartkrans and Sterkfontein, South Africa

The phylogenetic relationships of early Pleistocene Homo crania from the South African sites of Swartkrans and Sterkfontein were investigated through cladistic analyses of 99 morphological characters. The Swartkrans Member 1 specimen SK 847 and the Stw 53 cranium from Sterkfontein Member 5A were treated as separate operational taxonomic units (OTUs), distinct from the three species of early Homo-H. erectus, H. habilis, and H. rudolfensis-that are recognized from the Plio-Pleistocene deposits of East Africa. The cladistic analyses differed in the treatment of the South African OTUs (separate Swartkrans and Sterkfontein OTUs vs. a single Swartkrans+Sterkfontein OTU). PAUP 4.0 was used to construct cladograms and address hypotheses about relationships. In the analysis that treated the South African specimens as a single OTU, the position of that OTU was stable as a separate branch on the Homo clade between H. rudolfensis and [H. habilis+(H. erectus+H. sapiens)]. When SK 847 and Stw 53 were treated as separate OTUs, the majority of most parsimonious trees indicated that they were positioned in similar positions as the combined South African Homo OTU; that is, as separate branches between H. rudolfensis and [H. habilis+(H. erectus+H. sapiens)], with the Swartkrans OTU generally occupying a more derived position. The position of the Sterkfontein OTU was more stable than that of the Swartkrans OTU, which was found in several other positions among the minimum length trees. Running the analyses with only those characters preserved by SK 847 and Stw 53 resulted in similar topologies for minimum length trees, although the positions of Stw 53, SK 847, and H. habilis exchanged places in some trees. In no case was an exclusive sister relationship between either South African OTU and a particular species of Homo supported statistically. Both South African OTUs differ from H. habilis in the fewest number of cladistic characters.     

Taxonomic affinity of the early Homo cranium from Swartkrans,South Africa

A quantitative analysis that employs randomization methods and distance statistics has been undertaken in an attempt to clarify the taxonomic affinities of the partial Homo cranium (SK 847) from Member 1 of the Swartkrans Formation. Although SK 847 has been argued to represent early H. erectus, exact randomization tests reveal that the magnitude of differences between it and two crania that have been attributed to that taxon (KNM-ER 3733 and KNM-WT 15000) is highly unlikely to be encountered in a modern human sample drawn from eastern and southern Africa. Some of the variables that differentiate SK 847 from the two early H. erectus crania (e. g., nasal breadth, frontal breadth, mastoid process size) have been considered to be relevant characters in the definition of that taxon. Just as the significant differences between SK 847 and the two early H. erectus crania make attribution of the Swartkrans specimen to that taxon unlikely, the linkage of SK 847 to KNM-ER 1813, and especially Stw 53, suggests that the Swartkrans cranium may have its closest affinity with H. habilis sensu lato. Differences from KNM-ER 1813, however, hint that the South African fossils may represent a species of early Homo that has not been sampled in the Plio-Pleistocene of eastern Africa. The similarity of SK 847 and Stw 53 may support faunal evidence which suggests that Sterkfontein Member 5 and Swartkrans Member 1 are of similar geochronological age. © 1993 Wiley-Liss, Inc.     

Number of ancestral human species: a molecular perspective

Despite the remarkable developments in molecular biology over the past three decades, anthropological genetics has had only limited impact on systematics in human evolution. Genetics offers the opportunity to objectively test taxonomies based on morphology and may be used to supplement conventional approaches to hominid systematics. Our analyses, examining chromosomes and 46 estimates of genetic distance, indicate there may have been only around 4 species on the direct line to modern humans and 5 species in total. This contrasts with current taxonomies recognising up to 23 species.

The genetic proximity of humans and chimpanzees has been used to suggest these species are congeneric. Our analysis of genetic distances between them is consistent with this proposal. It is time that chimpanzees, living humans and all fossil humans be classified in Homo. The creation of new genera can no longer be a solution to the complexities of fossil morphologies. Published genetic distances between common chimpanzees and bonobos, along with evidence for interbreeding, suggest they should be assigned to a single species.

The short distance between humans and chimpanzees also places a strict limit on the number of possible evolutionary side branches that might be recognised on the human lineage. All fossil taxa were genetically very close to each other and likely to have been below congeneric genetic distances seen for many mammals.

Our estimates of genetic divergence suggest that periods of around 2 million years are required to produce sufficient genetic distance to represent speciation. Therefore, Neanderthals and so-called H. erectus were genetically so close to contemporary H. sapiens they were unlikely to have been separate species. Thus, it is likely there was only one species of human (H. sapiens) for most of the last 2 million years. We estimate the divergence time of H. sapiensfrom 16 genetic distances to be around 1.7 Ma which is consistent with evidence for the earliest migration out of Africa. These findings call into question the mitochondrial «African Eve» hypothesis based on a far more recent origin for H. sapiens and show that humans did not go through a bottleneck in their recent evolutionary history.

Given the large offset in evolutionary rates of molecules and morphology seen in human evolution, Homo species are likely to be characterised by high levels of morphological variation and low levels of genetic variability. Thus, molecular data suggest the limits for intraspecific morphological variation used by many palaeoanthropologists have been set too low. The role of phenotypic plasticity has been greatly underestimated in human evolution.

We call into question the use of mtDNA for studies of human evolution. This DNA is under strong selection, which violates the assumption of selective neutrality. This issue should be addressed by geneticists, including a reassessment of its use for molecular clocks. There is a need for greater cooperation between palaeoanthropologists and anthropological geneticists to better understand human evolution and to bring palaeoanthropology into the mainstream of evolutionary biology.     

中国丝盖伞属裂盖组的三个新种

丝盖伞属裂盖组Inocybe sect. Rimosae sensu lato是一个分类难度较大的类群,组内的一些种类被认为是复合种。分子系统发育分析表明该组并非单系群,该组成员隶属于丝盖伞科下的2个属级分支,Inosperma分支和Pseudosperma分支。本文结合形态学特征和分子序列分析,对我国丝盖伞属裂盖组进行了分类学研究,发现3个新种：长白丝盖伞Inocybe changbaiensis、新茶褐丝盖伞I. neoumbrinella和云南丝盖伞I. yunnanensis。长白丝盖伞和新茶褐丝盖伞产自中国东北,前者生于针阔混交林下,后者生于柳树林下;云南丝盖伞产自云南省昆明市,生于阔叶树下。基于LSU序列的系统发育分析结果显示,长白丝盖伞隶属于Inosperma分支,新茶褐丝盖伞和云南丝盖伞隶属于Pseudosperma分支。本文对此进行了形态描述和特征图示,并讨论了新种与近缘种之间的异同。编制了中国丝盖伞属裂盖组已知种类的分种检索表。     

Isolation of leishmanial parasites from a wild caught Anopheles gambiae mosquito in Kenya

A total of 232 mosquitoes were collected and dissected for leishmanial parasites in the Baringo District, Kenya. Anopheles gambiae sensu lato comprised 90.9% of the sample. One female A. gambiae was found to be infected with leishmanial promastigotes. The parasites when injected into Balb C mice caused skin lesions characterized by heavy amastigote infections. The average size of the parasite was: body length, 11.7 ± 0.19 μm; width, 1.3 ± 0.04 μm; flagellum length, 15.5 ± 0.28 μm.     

The natural history of the helicoidal occlusal plane and its evolution in early Homo

In modern man the pitch of the occlusal plane may vary along the tooth-row. When anterior cheek-teeth show a plane sloping upward palatally, whilst that on posterior cheek-teeth slopes upward buccally, there results a twisted or helicoidal occlusal plane (Ackermann). Several hypotheses have been proposed for the structural basis of the helicoidal occlusal plane. Campbell's proposal ('25) has gained widest acceptance, namely that the helicoid results from anteroposterior differences in upper and lower alveolar arch width. In the early 1960s, while studying the Olduvai hominids assigned to Homo habilis, the author noted changing occlusal slopes along the tooth-row and a slight helicoid, although these featues had not been noted in other early hominids. Subsequently, Wallace showed a total absence of the helicoid from South African australopithecines, and its presence in Swartkrans Homo, SK 45 and SK 80. Recent studies confirm the presence of the helicoid in all available specimens of H. habilis, including Stw 53 found at Sterkfontein in 1976. Hence, this trait may distinguish between Australopithecus and early Homo. Measurements of the maxillary arch widths have shown that, whereas in Australopithecus arch widths increase to a maximum at M3, in early Homo maxillary arch widths are greatest at M2. The decline in posterior maxillary arch width is part of a general reduction of that region. Thus despite striking elongation of premolars and M1 in early Homo, M2 and M3 are mesiodistally abbreviated. It is hypothesized that the onset of posterior arch reduction, with the appearance of a helicoid, was a structural and functional concomitant of the transition from the presumed australopithecine ancestor to H. habilis.     

周口店直立人头骨创伤与人工切割痕迹辨析

自20世纪40年代魏敦瑞提出北京猿人（周口店直立人）可能存在“暴力争斗”和“同类残食”的观点之后,引发了一些学者和科普大众对北京猿人是否为“食人族”的争论。由于原始化石标本在第二次世界大战期间丢失,本文以保存下来的周口店（ZKD）直立人头骨原始模型和素描图为研究材料,对魏敦瑞提出的具有创伤和人工切割痕迹的5件标本（ZKD II、ZKD VI、ZKD X、ZKD XI和ZKD XII）进行辨析。结果显示：1）ZKD X、ZKD XI、ZKD XII这3件标本的头盖部,有7处可以确定为生前遭受非致死性撞击导致的局部创伤;2）ZKD VI头盖骨残片周边的及中央区域的断痕,为个体生前遭受致死性的暴力打击导致;3）ZKD II和ZKD VI顶骨位置疑似人工切割痕迹的沟槽实际上是动物啃咬或自然因素导致的,北京猿人“同类残食”的观点在本文研究中没有得到证实。北京猿人头骨的创伤痕迹都位于头盖部,以顶骨居多,其次为额骨,符合人群之间暴力冲突产生创伤的位置。     

中国西北地区萱草属花粉形态研究

本文借助光学显微镜和扫描电镜,对我国西北地区萱草属6种1变种的花粉形态进行了比较研究,不同的种类,其花粉形态或多或少有所不同,说明花粉形态在种间具有分类意义,而且6种、1变种可自然地分为两大类群,第一类群包括小黄花菜、北萱草、黄花菜,第二类群包括北黄花菜、折叶萱草、萱草、重瓣萱草。#br#北黄花菜、小黄花菜的花粉形态差别较大,证明把小黄花菜做为北黄花菜的变种是不妥当的。     

中国古人类颅容量的推算方法比较

古人类的体质特征和现代人不同,依据现代人头骨测量数据计算出来的公式往往不适于古人类颅容量的推算。获取古人类颅容量最准确的方法是复原出其内部的颅内模;然而,由于颅内模的复原工艺复杂,加上古人类头骨化石数量稀少且多数残破,如何准确地推算其颅容量,成为古人学者研究的难点问题之一。本文通过对中国境内发现的不同演化阶段的古人类颅容量推算方法的对比和验证,试图找出推算古人类颅容量的最适合的公式法。研究结果显示：1）早期现代人解剖特征同现代人基本接近,依据现代人头骨推算出来的回归方程可以用来推算其颅容量;2）直立人头骨厚重、脑颅低矮,体质特征不同于现代人,其颅容量的推算不能使用现代人公式法。依据本文中国直立人头骨测量数据推导出来的回程方程（C=-1301.944+60606L+0.718b+9.936h）适合其颅容量的推算。采用此直立人公式法,推算出蓝田直立人的颅容量为918 mL;3）古老型智人的体质特征位于直立人和现代人之间,对其颅容量的推算不能一概而论：体质特征接近直立人的,如大荔人、华龙洞6号,可采用直立人公式法;体质特征接近早期现代人的,如许昌1号,可采用现代人公式法;体质特征位于直立人和早期现代人中间位置的,如马坝人、金牛山人,其颅容量约等于采用现代人公式法和采用直立人公式法获得的颅容量的平均值。     

直翅目虫草（肉座菌目）：物种多样性及其与寄主的关系

迄今为止,以直翅目昆虫为寄主的虫草共报道25种,本研究详细介绍了它们的种类、寄主与分布,并给出了相关的分类学注释。ITS和tef1-α基因联合数据的分子系统发育显示,直翅目虫草分别隶属于白僵菌属Beauveria、绿僵菌属Metarhizium和线虫草属Ophiocordyceps 3个属。基于直翅目昆虫六大类群的生态习性特点,分析并讨论了直翅目虫草物种多样性与寄主的关系。以两种白僵菌Beauveria及戴氏虫草Metacordyceps taii（贵州绿僵菌Metarhizium guizhouense的异名）为例,介绍了虫草的根状菌索,一种介于子实体和孢梗束形体之间的根须状结构。种类修订：蟋螽白僵菌新组合Beauveria grylli comb. nov. ≡ 蟋蟀虫草Cordyceps grylli = Beauveria loeiensis,Beauveria kirkii comb. nov. ≡ Cordyceps kirkii。寄主更正：蟋螽白僵菌的寄主由原来的蟋蟀成虫（蟋蟀科Gryllidae）更正为螽斯（蟋螽）若虫（蟋螽科Gryllacrididae）,蟋蟀线虫草Ophiocordyceps tettigonia 寄主由原来的螽斯成虫（螽斯科Tettigoniidae：螽斯属Tettigonia）更正为蟋蟀成虫（蟋蟀科）。     

Craniofacial morphology of Homo floresiensis: description, taxonomic affinities, and evolutionary implication

This paper describes in detail the external morphology of LB1/1, the nearly complete and only known cranium of Homo floresiensis. Comparisons were made with a large sample of early groups of the genus Homo to assess primitive, derived, and unique craniofacial traits of LB1 and discuss its evolution. Principal cranial shape differences between H. floresiensis and Homo sapiens are also explored metrically. The LB1 specimen exhibits a marked reductive trend in its facial skeleton, which is comparable to the H. sapiens condition and is probably associated with reduced masticatory stresses. However, LB1 is craniometrically different from H. sapiens showing an extremely small overall cranial size, and the combination of a primitive low and anteriorly narrow vault shape, a relatively prognathic face, a rounded oval foramen that is greatly separated anteriorly from the carotid canal/jugular foramen, and a unique, tall orbital shape. Whereas the neurocranium of LB1 is as small as that of some Homo habilis specimens, it exhibits laterally expanded parietals, a weak suprameatal crest, a moderately flexed occipital, a marked facial reduction, and many other derived features that characterize post-habilis Homo. Other craniofacial characteristics of LB1 include, for example, a relatively narrow frontal squama with flattened right and left sides, a marked frontal keel, posteriorly divergent temporal lines, a posteriorly flexed anteromedial corner of the mandibular fossa, a bulbous lateral end of the supraorbital torus, and a forward protruding maxillary body with a distinct infraorbital sulcus. LB1 is most similar to early Javanese Homo erectus from Sangiran and Trinil in these and other aspects. We conclude that the craniofacial morphology of LB1 is consistent with the hypothesis that H. floresiensis evolved from early Javanese H. erectus with dramatic island dwarfism. However, further field discoveries of early hominin skeletal remains from Flores and detailed analyses of the finds are needed to understand the evolutionary history of this endemic hominin species.     

Cranial morphometry of early hominids: facial region

We report here on early hominid facial diversity, as part of a more extensive morphometric survey of cranial variability in Pliocene and early Pleistocene Hominidae. Univariate and multivariate techniques are used to summarise variation in facial proportions in South and East African hominids, and later Quaternary groups are included as comparators in order to scale the variation displayed. The results indicate that "robust" australopithecines have longer, broader faces than the "gracile" form, but that all australopithecine species show comparable degrees of facial projection. "Robust" crania are characterised by anteriorly situated, deep malar processes that slope forwards and downwards. Smaller hominid specimens, formally or informally assigned to Homo (H. habilis, KNM-ER 1813, etc.), have individual facial dimensions that usually fall within the range of Australopithecus africanus, but which in combination reveal a significantly different morphological pattern; SK 847 shows similarly hominine facial proportions, which differ significantly from those of A. robustus specimens from Swartkrans. KNM-ER 1470 possesses a facial pattern that is basically hominine, but which in some respects mimics that of "robust" australopithecines. Early specimens referred to H. erectus possess facial proportions that contrast markedly with those of other Villafranchian hominids and which suggest differing masticatory forces, possibly reflecting a shift in dietary niche. Overall the results indicate two broad patterns of facial proportions in Hominidae: one is characteristic of Pliocene/basal Pleistocene forms with opposite polarities represented by A. boisei and H. habilis; the other pattern, which typifies hominids from the later Lower Pleistocene onwards, is first found in specimens widely regarded as early representatives of H. erectus, but which differ in which certain respects from the face of later members of that species.     

Multilocus sequence analysis of Fusarium pseudograminearum reveals a single phylogenetic species

Fusarium pseudograminearum causes crown rot of wheat in Australia and most other wheat growing regions, but its evolutionary history is largely unknown. We demonstrate for the first time that F. pseudograminearum is a single phylogenetic species without consistent lineage development across genes. Isolates of F. pseudograminearum, F. graminearum sensu lato, and F. cerealis, were collected from four countries and four single copy, nuclear genes were partially sequenced, aligned with previously published sequences of these and related species, and analysed by maximum parsimony and Bayesian inference. Evolutionary divergence varied between genes, with high phylogenetic incongruence occurring between the gene genealogies. The absence of geographic differentiation between isolates indicates that the introduction of new fungal strains to a region has the potential to introduce new pathogenic and toxigenic genes into the native population through sexual recombination.     

Correlation of self- and interspecific incompatibility among sympatric Hedyotis species (Rubiaceae) and consequences for hybridization

Breakdown of self-incompatibility increases opportunities for both self-fertilization and interspecific hybridization, although the latter is dependent on the extent of competition between heterospecific and conspecific pollen. We investigate the mating system and pollination biology of five phylogenetically closely related species within a distylous species complex in Hedyotis L. (Rubiaceae) in southern China. The complex comprises Hedyotis acutangula Champ. ex Benth., Hedyotis shiuyingiae T.Chen, Hedyotis vachellii (Hook. & Arn.) Kuntze, and two putative hybrid species, Hedyotis bodinieri (H.Lév.) Chun and Hedyotis loganioides Benth., hypothesized to result from interbreeding between these species. We test the hypothesis that the breakdown of self- and interspecific incompatibilities in sympatric Hedyotis species might allow interspecific hybridization in natural populations. We assessed the extent of self- and interspecific incompatibility in sympatric populations, including investigations of spontaneous and artificial self-pollination, geitonogamy, inter- and intramorph xenogamy. Artificial interspecific crosses were undertaken between H. acutangula, H. shiuyingiae, and H. bodinieri, between H. acutangula and H. vachellii, and between H. acutangula and H. loganioides. Hedyotis acutangula is demonstrated to be self- and interspecific compatible, whereas H. vachellii, H. bodinieri, and H. loganioides are self-compatible and interspecific incompatible; H. shiuyingiae, in contrast, is strictly self- and interspecific incompatible. Comparisons of pollen tube growth rates in hybridizing species-pairs revealed that heterospecific pollen of H. shiuyingiae, H. vachellii, and H. bodinieri can compete with conspecific self-pollen of H. acutangula. Our study therefore indicates that the breakdown of self-incompatibility directly and indirectly facilitates interspecific hybridization and provides a platform for better understanding evolutionary directionality in Hedyotis.     

Flavonoids of five Hieracium species of British Columbia

Five Hieracium species were examined for flavonoid constituents: H. albertinum, H. albiflorum, H. cynoglossoides, H. gracile and H. umbellatum. The major compounds present in all species were mono- and diglycosides, of apigenin and luteolin. Chrysoeriol occurred per se in several species. Quercetin-3-O-glucoside was seen only in H. umbellatum. Species specific patterns of flavonoid glycosides were evident in all five taxa; H. albertinum and H. cynoglossoides showed the greatest similarity which reflects their morphological similarity. Limited examination of artificial hybrids showed additivity of flavonoid glycoside patterns.     

Comparative phylogenetic analyses of Chinese Horsfieldia (Myristicaceae) using complete chloroplast genome sequences

The biologist's ruler for biodiversity is the species; accurate species identification is fundamental to the conservation of endangered species and in-depth biological scientific exploration. However, the delimitation and affinities of Horsfieldia in China has been controversial, owing in part to very low levels of molecular divergence within the family Myristicaceae. Because species boundaries and phylogenetic relationships within Horsfieldia are also unclear, 13 samples were collected across its distribution in China and their genomes were subjected to shotgun sequencing using Illumina platforms. A total of 40 487 994–84 801 416 pair-end clean reads were obtained and, after assembly, the complete chloroplast genome was recovered for all samples. Annotation analysis revealed a total of 112 genes, including 78 protein-coding genes, 30 transfer RNA, and 4 ribosomal RNA genes. Six variable loci (petN-psbM, trnH-psbA, ndhC-trnV, psbJ-psbL, ndhF, and rrn5-rrn23) were identified. Phylogenetic analyses strongly support the presence of four distinct species of Horsfieldia in China. In addition, samples that had been identified previously as Horsfieldia kingii (Hook. f.) Warb. were indistinguishable from those of H. prainii (King) Warb., suggesting that if H. kingii does occur in China, it was not collected in this study. Similarly, the chloroplast genome of one H. hainanensis Merr. sample from Guangxi province was identical to H. tetratepala C. Y. Wu, suggesting that the distribution range of H. hainanensis might be narrower than assumed previously. The phylogenetic relationships between the Chinese Horsfieldia species based on the whole chloroplast genomes was supported strongly, indicating the potential for using entire chloroplast genomes as super-barcodes for further resolution of the phylogeny of the genus Horsfieldia.     

Hemiasterid echinoids (Echinodermata: Spatangoida) from the Cretaceous Tethys to the present-day Mediterranean

Hemiasterid echinoids form one of the oldest and most varied spatangoid groups. Current data on stratigraphical and geographical distribution pattern show that their biogeographical history is closely related to Mediterranean-Tethyan structural and climatic changes. The group first appeared in the Aptian in the central Tethys (southwestern Europe) and developed and diversified remarkably in the Late Cretaceous through the subgenera Hemiaster (Hemiaster), H. (Bolbaster) and H. (Leymeriaster). Marked morphological changes arose in the early Paleogene when new Tertiary forms H. (Trachyaster), Opissaster and Ditremaster, originating in the Caribbean and Madagascan regions, respectively, replaced H. (Bolbaster) which partly survived and H. (Hemiaster) and H. (Leymeriaster) which disappeared entirely. These new forms achieved their greatest diversity during the Eocenee and thrived in the Mediterranean basin until it was sealed off from the Indo-Pacific in the Middle Miocene. Then Late Neogene climatic and structural events reduced hemiasterids to only a few Mediterranean species. The survivors of modern groups persisted in refuge areas of the western Mediterranean until middle Messinian times before being reduced to only one species, the last fossil one, during the Pliocene. Then, the Cenozoic groups H. (Trachyaster) and Opissaster definitively disappeared. Outside the Mediterranean basin primitive H. (Bolbaster) and modern Ditremaster, which colonized deep-water Atlantic environments from the Late Cretaceous and Middle Miocene respectively, survived the Messinian and Plio-Pleistocene climatic crises. They flourished in the northern Atlantic where their present-day descendants Ditremaster (Sarsiaster) griegii and H. (Bolbaster) expergitus still survive. H. (Bolbaster) expergitus spread worldwide and colonized the western Mediterranean in the Plio-Pleistocene via the Straits of Gibraltar.