The Origin and Dispersal of the “Lower” Hamamelidae

The “lower” Hamamelidae sensu Endress (1989a) comprises seven families: Trochodendraceae, Tetracentraceae, Cercidiphyllaceae, Myrothamnaceae, Eupteleaceae, Platanaceae and Hamamelidaceae. In the present paper, the systematic position, modern distribution pattern and fossil history of each family are analyzed, and the origin and dispersal of them are discussed according to the principle of the unity between the phylogeny and distribution of plants. The paper consists of three parts. The conclusions are as follows: 1. The center of distribution According to Takhtajan's (1986) regionalization of the world flora, there are 13 distribution types in the “lower” Hamamelidae (Table 1 ). Eastern Asiatic Region, with five families, 19 genera and 73 species, ranks the first based on the numbers of species, genera and families. Four families: Trochodendraceae, Tetracentraceae, Cercidiphyllaceae and Eupteleaceae which were considered as more primitive in the “lower” Hamamelidae and three genera: Disanthus, Exbucklandia and Rhodoleia, primitive in the Hamamelidaceae, are all found in Eastern Asiatic Region. In addition, the groups at different evolutionary stages in the “lower” Hamamelidae survive in this region. Indochinese Region, with two families, 15 genera and 32 species, ranks the second. It was shown that southern Eastern Asiatic region and northern Indochinese Region are the distribution center of the “lower”Hamamelidae based on further analysis (see Table 2). 2. The place and time of the origin The fossil records of the “lower” Hamamelidae are abundant in angiosperms. Nordenskioldia, supposed as the extinct ancestral group of Trochodendraceae and Tetracentraceae, was widely distributed during the latest Cretaceous and the early Tertiary in the Northern Hemisphere; Trochodendroides appeared during the Cretaceous in North America, former USSR and Japan; the ancestral group of Cercidiphyllaceae, the Joffrea-Nyssidum complex, also occurred during the Cretaceous in the middle and higher latitude area of the Norhern Hemisphere. In addition, the earliest fossil records of the Eupteleaceae, Platanaceae and Hamamelidaceae appeared in North America, Europe and Asia of the Northern Hemisphere respectively. Therefore, the Laurasian origin of the “lower” Hamamelidae is supported by fossil evidence. On the other hand, the fossil data are still insufficient to determine the place of the origin, especially because the fossil records are rather poor in Asia. For this reason, the analyses of birthplace should combine with the information from the distribution of the primitive groups or outgroup of the “lower” Hamamelidae. Based on the statistics of distribution types, there are four primitive families in the “lower” Hamamelidae and three primitive genera in the Hamamelidaceae in southern Eastern Asiatic Region and northern Indochinese Region. Platanus kerrii Gagnep. of the Platanaceae, distributed in northern Vietnam, is considered as one of the most primitive species which has survived in modern times in this family because of its pistillate inflorescence comprising 10-12 heads. The Magnoliaceae was selected as an outgroup in our other paper “A phylogenetic analysis of families in the Hamamelidae” (Lu et al. 1991 ). All its 13 genera and most species occur from East to Southeast Asia, but in North America only three genera are found. Takhtajan (1969) considered that it was plants of the Magnoliaceae that were dispersed from East Asia to North America. Because the primitive groups of the “lower” Hamamelidae and its outgroup almost occur in the same area, their ancestor also appeared most probably in this area according to the principle of common origin. It was inferred that the area from southern Eastern Asiatic Region to northern Indochinese Region is the birthplace of the “lower"” Hamamelidae. The differentiation of the “lower” Hamamelidae took place rather early in angiosperms. The origin of them may be traced at least back to the Barremian of the early Cretaceous according to pollen fossil records. From more unequivocal fossil evidence, Platanoid plants appeared during the late Albian of the early Cretaceous, and the Trochodendraceae, Tetracentraceae, Cercidiphyllaceae and Hamamelidaceae diverged from their ancestral groups respectively no later than the late Cretaceous (Fig. 6). 3. The causes for the formation of the modern distribution pattern The “lower” Hamamelidae is a. rather old group. It is one of the most abundant and widespread components of fossil floras in the Northern Hemisphere during the late Cretaceous-middle Tertiary, the interval, when the global temperature was warm, although the extant Trochodendraceae, Tetracentraceae, Cercidiphyllaceae and Eupteleaceae which are now confined to East Asia are monotypical or oligotypical families. This distribution pattern indicates that most plants became extinct in Europe, northern Asia and North America because of the climatic changes during the late Tertiary, and especially the Quaternary glaciation, but East Asia, usually called “plant refuge”during the glacial period, became the survival place of many plants. From the viewpoint of evolution, these four families might be “living fossil plants” preserved from the Tertiary. The distribution of Hamamelidaceae is disjunct, but the causes leading to this pattern are not the same in different genera. The disjunction among Europe, North America, Australia and southern Africa is due to the tectonic movements of the earth; , and that between southeastern Europe-northern West Asia and southeastern Asia is developed as a result of the Quaternary glaciation. Fothergilla found from Carolina to Alabama in the United States and Hamamelis disjunct between East Asia and North America were widely distributed during the Tertiary in the Northern Hemisphere (Hu & Chaney 1940). The formation of their distribution patterns is a synthetic process owing to the tectonic movements and the Quaternary glaciation. Parrotia and Parrotiopsis, endemic to Iran and the West Himalayas respectively, are very similar in morphology. They might have a common ancestor, and the latter is more primitive than the former. It seems that several groups in the Hamamelidaceae were dispersed from east to west in Eurasia. Of the five genera in the Southern Hemisphere, Dicoryphe and Trichocladus are Madagascarian and southern African, and Ostrearia, Neostrearia and Noahdendron occur in northeastern Australia. They are usually considered as rather isolated groups, but Hufford and Endress (1989) found that they are closely related. The African genera might be dispersed from Asia via India, Sri Lanka and Lemuria continent; the Australian Hamamelidaceae also from Asia, but via the islands distributed in the Pacific Ocean. The Myrothamnaceae, comprising 2 species distributed in Madagascar and southern Africa, is closely related to the Hamamelidaceae. Based on morphological analyses, an evolutionary series exists among Myrothamnus, Dicoryphe and Trichocladus in which the distribution patterns are the same, and Myrothamnus is more specialized than the two genera of the Hamamelidaceae. 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Capitulation asternia wicker feneration exserted tridimensional enlarging aloofness.     

Genetics and the Origin of Human “Races”

In the last decades, the concept of human races was considered scientifically unfounded as it was not confirmed by genetic evidence. None of the racial classifications, which strongly differ in the number of races and their composition, reflects actual genetic similarity and genealogy of human populations inferred from variability of classical markers and DNA regions. Moreover, intercontinental (interracial) variability was shown to be far lower than that within populations: the former constitutes 7 to 10% of the total genetic variation and the latter about 85% of it. It is believed that the low level of differentiation of regional population groups contradicts their race status and suggests a recent origin of humans from one ancestral population. The results of studies of various genetic systems are in agreement with the latter conclusion rejecting the hypothesis of regional continuity. According to this hypothesis, the populations of continents regarded as large races have developed during long evolution from local types of archaic humans, in particular, Neanderthals. Phenotypic similarity of different, sometimes unrelated, populations united into one race is explained by strong selection since race-diagnostic traits characterize body surface and thus are directly subjected to the influence of environmental (primarily climatic) factors. It has been recently established that variability of the most important of these traits, body and hair pigmentation, is largely controlled by one locus (MC1R), which accounts for its high evolutionary lability. Other traits used for race identification are also likely to be labile and controlled by major genes. However, the fact that the currently existing race classifications are groundless does not mean that such classifications are impossible in principle. Commonly used argumentation (races do not exist because populations are not genetically separated) does not hold water. A polytypic species is characterized by genetic continuity of allopatric populations rather than the presence of narrow genetic boundaries between them. Borderlines between races are usually conventional and arbitrary. As to intergroup variation in humans, it is indeed low but comparable with that in a number of other species. There are no obstacles to the development of genetic systematics of human races.     

The Impact of the Species–Area Relationship on Estimates of Paleodiversity

Estimates of paleodiversity patterns through time have relied on datasets that lump taxonomic occurrences from geographic areas of varying size per interval of time. In essence, such estimates assume that the species–area effect, whereby more species are recorded from larger geographic areas, is negligible for fossil data. We tested this assumption by using the newly developed Miocene Mammal Mapping Project database of western North American fossil mammals and its associated analysis tools to empirically determine the geographic area that contributed to species diversity counts in successive temporal bins. The results indicate that a species–area effect markedly influences counts of fossil species, just as variable spatial sampling influences diversity counts on the modern landscape. Removing this bias suggests some traditionally recognized peaks in paleodiversity are just artifacts of the species–area effect while others stand out as meriting further attention. This discovery means that there is great potential for refining existing time-series estimates of paleodiversity, and for using species–area relationships to more reliably understand the magnitude and timing of such biotically important events as extinction, lineage diversification, and long-term trends in ecological structure.     

Studies on the Origin of the Traditional Chinese Drug “Jinxiong”

A comparison of morphology, karyotype and the chemical compounds among “Jinxiong”, Ligasticum chuanxiong Hort. and L. chuanxiong cv. Fuxiong shows that “Jin-xiong”, like L. chuanxiong cv. Fuxiong, is a triploid and its karyotype is similar to that of L. chuanxiong with the formula K(2n)=33=24m+6sm+3st(SAT). Thin-layer chromatography of essential oils extracted from stem tubers confirms that the three taxa are extremely alike in chemical compounds. Using the features of leaves and the forms of stem tubers, they can be easily distinguished. A new triploid cultivar of L. chuanxiong Hort. i.e.L. chuan-xiong cv. Jinxiong is described for “Jinxiong” in the present paper.     

Malaria: Origin of the Term “Hypnozoite”

The term “hypnozoite” is derived from the Greek words hypnos (sleep) and zoon (animal). Hypnozoites are dormant forms in the life cycles of certain parasitic protozoa that belong to the Phylum Apicomplexa (Sporozoa) and are best known for their probable association with latency and relapse in human malarial infections caused by Plasmodium ovale and P. vivax. Consequently, the hypnozoite is of great biological and medical significance. This, in turn, makes the origin of the name “hypnozoite” a subject of interest. Some “missing” history that is now placed on record (including a letter written by P. C. C. Garnham, FRS) shows that Miles B. Markus coined the term “hypnozoite”. While a PhD student at Imperial College London, he carried out research that led to the identification of an apparently dormant form of Cystoisospora (synonym: Isospora). In 1976, he speculated: “If sporozoites of Isospora can behave in this fashion, then those of related Sporozoa, like malaria parasites, may have the ability to survive in the tissues in a similar way.” He adopted the term “hypnozoite” for malaria in 1978 when he wrote in a little-known journal that this name would “… describe any dormant sporozoites or dormant, sporozoite-like stages in the life cycles of Plasmodium or other Haemosporina.” At that time, the existence of a hypnozoite form in the life cycle of Plasmodium was still a hypothetical notion. In 1980, however, Wojciech A. Krotoski published (together with several co-workers) details concerning his actual discovery of malarial hypnozoites, an event of considerable importance.     

The Other Edge of Ockham’s Razor: The A-PR Hypothesis and the Origin of Mind

Charles Darwin’s theory of evolution characterized all life as engaged in a “struggle for existence”. To struggle requires internal data processing to detect and interpret patterns to guide behavior, a mechanism to struggle for existence. The cognitive bootstrapping A-PR cycle (Autonomy | Pattern Recognition) couples the origin of life and mind, enabling their symbiotic co-evolution. Life processes energy to create order. Mind processes data to create meaning. Life and mind co-evolve toward increased functional effectiveness, using A-PR feedback cycles that reflect the two Laws deduced from Ockham’s Razor. The Law of Parsimony is only one of two laws that have emerged from debate about Ockham’s Razor. Less well known is the “other edge of Ockham’s Razor”, the Law of Succinctness which, when viewed through the lens of Charles Darwin’s theory of evolution, enables the A-PR Hypothesis to fulfill the criteria of Ockham’s Razor.     

“The tools of the discipline: Biochemists and molecular biologists”: A comment

Conclusion and Issues for Further Investigation This last result leads, rather naturally, to some concluding observations and a series of questions for further investigation. These case studies show that in all of the sites examined, the institutionalization of molecular biology as a discipline was primarily driven by the need to separate groups of practitioners with divergent but overlapping interests within the local context. Thus molecular biology was contingently separated from agricultural or medical biochemistry, virology, work on the physiology of nucleic acids, and so forth for contingent local institutional reasons. This makes it even more pressing to try to understand how molecular biology came to be delimited on a larger scale. How did it come to be a discipline with specific intellectual content (or did it?), including some problems, tools, and practices and excluding others? How did it gain authority as the forefront biological science by the mid-1960s? We need to understand the ways in which the tensions between different practices, projects, aims, understandings of the goals of molecular biology, and so on were resolved, on what scale and in what venues, so that something approximating the political character of a discipline, rather than a federation, was achieved. If these case studies provide a sound starting point, it will nevertheless prove difficult to answer the interconnected questions implicit here satisfactorily.One means of getting at such questions that should prove of considerable interest is to examine carefully the work of those who were widely cited in the papers of the late fifties through the mid-seventies by the people now considered major founders of molecular biology. By studying the contributions of those who are now omitted in the standard histories and recollections, we will gain a clearer sense of the possibilities that were open as molecular biology took shape. It is already widely recognized that the contributions of a number of biochemists have been given short shrift, but (as the example of Ernest Gale in Rheinberger's study illustrates) there are a great many more figures whose line of work were then crucial but who are now overlooked.⁶ To understand both what molecular biology was at the time of its early institutionalization and what is has become, it will be enormously helpful to understand at what point the definition or ideology hardened and the grounds for inclusion and exclusion of individuals and lines of work were reformed. Studies of this sort are appropriate in many other areas as well, of course; in general, they should different histories, political standing, and institutional bases of those disciplines in their national cultures. It is likely (but a matter for investigation!) that such differences influenced the opportunities for introducing new bench practices, if in no other way than by delimiting the niches within which certain practices could be initiated.⁷ And since new practices can fail to achieve their objectives, can transform the direction of work and disciplinary allegiances of their practitioners, can lead to only routine results, or can open up important new vistas, the character of the available niches from which to work can prove to have a strong influence on the direction that new work takes if and when it starts to flourish. A key aspect of this problematic (not yet adequately studied, I believe) is the problem of drawing boundaries between different kinds of work and determining where each should fit among established disciplines and/or within some new construct. To the extent that an international solution is ultimately achieved to such problems, it must surely be achieved in light of initially different ways of dealing with it in different countries.Underlying work of the sort we have been exploring is the thorny problem of how best to contextualize the work being studied. This, I believe, is one of the major historiographic problems that we must face in the history of science. It is by no means a new problem, of course, but a particularization of the age-old problem of the (seeming) overdetermination of historical events. If we deal with local cultures, to understand how they develop and their fate we need to understand their location within larger cultures. But it is utterly unclear how to draw appropriate boundaries on the relevant larger culture(s). As even this brief discussion has shown, institutional cultures, the cultures of sponsoring agencies, the culture of science (or of biological science, physical science, etc., as appropriate), and national cultures all can provide relevant contexts, all can occasionally determine the fate of work undertaken in a particular local context. The potentially intractable problem of delimiting the boundaries of investigation looms large here, but it is one that must be faced explicity if we are to profit fully from the enormously stimulating investigations of local cultures exemplified in the four papers published in this symposium. My own view is that we have no abstract standard available for determining which boundaries are appropriate to a given study, and, indeed, that no single contextualization is adequate to the examination of any given case, but that, nonetheless, we can (at least sometimes) distinguish useful and explanatory delimitations of the larger context from others that prove to be misleading.Against this background, I hope that the four papers published in this special issue will stimulate the readers of the JHB to carry out similar studies—that is, studies that seek to characterize and contextualize local experimental cultures —over a wide range of cases. I also hope that some of those who take up this challenge will deal with the larger questions raised by the need to find a way of balancing different, sometimes competing, contextualizations of such studies. The fact that any given case requires multiple contextualizations, resulting in multifaceted representations no one of which is alone adequate, will surely land us in fascinating, hopefully fruitful and productive, controversies.     

On the Origin of Rheumatoid Arthritis: The Impact of Environment and Genes—A Population Based Twin Study

Background

Rheumatoid arthritis (RA) is an autoimmune disease with a complex origin. Previous studies have reported heritability estimates on RA at about 60%. Only 16% of the genetic background of the disease has been disclosed so far. The purpose of the present investigation was to provide an optimized estimate on the heritability of RA and to study the recurrence risk in a nationwide Caucasian twin population.

Methods and Findings

In a mail survey addressed to 56.707 twin individuals, RA was reported by 479 individuals, mean age 52 (range 16–73). Respondents underwent an interview and clinical examination. Ascertainment probability was 80%. RA was confirmed in 162 twin individuals yielding a prevalence at 0.37% (95% CI 0.31–0.43). The mean discordance time was 19 years (range 0–57). The concordance was 9.1% (95% CI 1.9 to 24.3) in MZ, 6.4% (95% CI 2.1 to 14.3) in DZss. The increased relative risk of attracting RA conditioned on having an affected cotwin compared to the background population risk was 24.6 to 35.4 in MZ twins and 17.3 to 31.6 in DZss twins. The correlation coefficients were 0.60 (0.33 to 0.78) in monozygotic (MZ) and 0.55 (0.33 to 0.72) in dizygotic same sexed (DZss) pairs. Twelve percent (95% CI 0–76%) of the phenotypic variance in the liability to RA was due to additive genetic effects, 50% (95% CI 0–72%) to shared environmental effects and 38% (95% CI 17–61%) to non-shared environmental effects.

Conclusions

This study emphasizes that family factors are important for the development of RA. Although genetic effectors are important, shared and non-shared environmental triggers and/or epigenetic stochastic events seem to be even more significant. However, it should be borne in mind that the genetic and non-genetic components may not be the same across disease subsets.     

A Cytotaxonomic Study on Chinese Dioscorea L.—The Chromosome Numbers and Their Relation to the Origin and Evolution of the Genus

The chromosome numbers of 5 tuberous sections of Chinese Dioscorea, including 23 species and varieties, are reported in the present paper as a continuation of the previous reports. They are all polyploids with the basic number x=10. On the basis of analysis of chromosome numbers of whole genus, the rhizomatous diploid species of Sect. Stenophora Uline are presumed to be primitive taxa, while the polyploids of chromosome numbers 40-142 are considered derived groups as a result of hybridization between their ancestral diploids followed by chromosome doubling. Sect. Lasiophyton Pr. et Burk., Sect. Opsophyton UIine, Sect. Shannicorea Pr. et Burk., Sect. Combilium Pr. et Burk. and Sect. EnantiophylIum Uline may be the advanced groups. The chromosomal evolution and geographical distribution suggest that the primitivediploid might have originated in Hengduan Mountains of Asia, an old highland.     

The Species and Origin of Shark Fins in Taiwan’s Fishing Ports,Markets, and Customs Detention: A DNA Barcoding Analysis

The increasing consumption of shark products, along with the shark’s fishing vulnerabilities, has led to the decrease in certain shark populations. In this study we used a DNA barcoding method to identify the species of shark landings at fishing ports, shark fin products in retail stores, and shark fins detained by Taiwan customs. In total we identified 23, 24, and 14 species from 231 fishing landings, 316 fin products, and 113 detained shark fins, respectively. All the three sample sources were dominated by Prionace glauca, which accounted for more than 30% of the collected samples. Over 60% of the species identified in the fin products also appeared in the port landings, suggesting the domestic-dominance of shark fin products in Taiwan. However, international trade also contributes a certain proportion of the fin product markets, as four species identified from the shark fin products are not found in Taiwan’s waters, and some domestic-available species were also found in the customs-detained sample. In addition to the species identification, we also found geographical differentiation in the cox1 gene of the common thresher sharks (Alopias vulpinus), the pelagic thresher shark (A. pelagicus), the smooth hammerhead shark (Sphyrna zygaena), and the scalloped hammerhead shark (S. lewini). This result might allow fishing authorities to more effectively trace the origins as well as enforce the management and conservation of these sharks.     

The Effect of a “Zero” Magnetic Field on the Production of Reactive Oxygen Species in Neutrophils

Exposure of mouse peritoneal neutrophils to hypomagnetic conditions (magnetic shielding, a residual static magnetic field of 20 nT) for 1.5 h decreased the level of intracellular reactive oxygen species as recorded by changes in the fluorescence intensity of 2,7-dichlorodihydrofluorescein and dihydrorhodamine 123 oxidation products. The effect of a hypomagnetic field was similarly observed after adding a respiratory burst activator (the formylated peptide N-formyl–Met–Leu–Phe or phorbol 12-meristate-13-acetate) to a low concentration.     

The Hybrid Origin of “Modern” Humans

Recent genomic research has shown that hybridization between substantially diverged lineages is the rule, not the exception, in human evolution. However, the importance of hybridization in shaping the genotype and phenotype of Homo sapiens remains debated. Here we argue that current evidence for hybridization in human evolution suggests not only that it was important, but that it was an essential creative force in the emergence of our variable, adaptable species. We then extend this argument to a reappraisal of the archaeological record, proposing that the exchange of cultural information between divergent groups may have facilitated the emergence of cultural innovation. We discuss the implications of this Divergence and Hybridization Model for considering the taxonomy of our lineage.     

A New Species of the Basal “Kangaroo” Balbaroo and a Re-Evaluation of Stem Macropodiform Interrelationships

Exceptionally well-preserved skulls and postcranial elements of a new species of the plesiomorphic stem macropodiform Balbaroo have been recovered from middle Miocene freshwater limestone deposits in the Riversleigh World Heritage Area of northwestern Queensland, Australia. This constitutes the richest intraspecific sample for any currently known basal “kangaroo”, and, along with additional material referred to Balbaroo fangaroo, provides new insights into structural variability within the most prolific archaic macropodiform clade – Balbaridae. Qualitative and metric evaluations of taxonomic boundaries demonstrate that the previously distinct species Nambaroo bullockensis is a junior synonym of B. camfieldensis. Furthermore, coupled Maximum Parsimony and Bayesian phylogenetic analyses reveal that our new Balbaroo remains represent the most derived member of the Balbaroo lineage, and are closely related to the middle Miocene B. camfieldensis, which like most named balbarid species is identifiable only from isolated jaws. The postcranial elements of Balbaroo concur with earlier finds of the stratigraphically oldest balbarid skeleton, Nambaroo gillespieae, and suggest that quadrupedal progression was a primary gait mode as opposed to bipedal saltation. All Balbaroo spp. have low-crowned bilophodont molars, which are typical for browsing herbivores inhabiting the densely forested environments envisaged for middle Miocene northeastern Australia.     

A New Species of “Tentacled” Marine Fish Leech Parasitic on Notothenia from the Subantarctic Marion and Crozet Islands

Summary A new species of marine fish leech parasitic on Notothenia coriiceps is described. Its relationships with the closely related Antarctobdella tcherniai Dollfus 1964 and Ophthalmobdella bellisioi Szidat 1965 are critically discussed.