买麻藤目的化石记录及其与 被子植物起源关系的探讨

二十世纪初，前人在中国的东北地区发现了大量保存完好的动物化石，其中以狼鳍鱼最具代表性，科学家将在该地区发现的化石生物群命名为“热河生物群”。“热河”这一名称得名于该化石群的经典产地，即当时的热河省东部地区。建国后，热河省被撤消，其西部划归河北省，东部划归辽宁省。原热河生物群的经典产地因此落在了今天辽宁省的西部，即辽西地区。但是，“热河生物群”这一在地质古生物学界具有深刻影响的名称仍然保留着，而且近几年来在该地区又有大量的鸟类以及恐龙的化石被发现。该地区现在已经成为世界级的古生物宝库。通过不同的方法对该地区进行时代测定的结果认为该地区的时代为白垩纪早期。 与发现众多、研究深入的动物群相比，在该地区开展的植物学研究起步较晚，但在最近几年取得了很大的进展。目前为止，已经发现的植物类群就有苔藓、蕨类、银杏、苏铁、松柏类和被子植物。其中，银杏、苏铁、松柏类尤为丰富。理论上，被子植物也正是从该生物群所代表的白垩纪早期开始出现并逐步走向繁荣的。近年来在热河生物群中就有不少关于被子植物早期类群的报道，如古果属A rchaefructus和里海果属Hyrcantha等。传统上认为，买麻藤目植物与被子植物起源的关系非常密切，但是最近的分子系统学研究却将该类群推离了被子植物，而作为裸子植物高等类群松柏类的姐妹群对待。但是，在热河生物群中的一些新买麻藤目植物的化石标本与被子植物早期类型化石标本的发现却提供了新的思路或证据。如近年来，我国学者已经在该生物群中报道的麻黄科下的2属4种。这些发现的类群都与买麻藤植物的基部类群麻黄属密切相关。这种新发现带来的证据或许可以为被子植物起源这一世界难题的解决提供新的思路。 在对前人关于买麻藤目植物化石标本的研究进行整理的时候，我们发现我们的部分化石与前人发表的一个种Ephedrites chenii在标本的形态学特征方面完全相同。但是在对该类群及其所在的属与麻黄的现代类群作对比研究后发现，该种植物的繁殖器官的特征完全符合麻黄属的特征，因此将该类群转移到麻黄属中作为新组合对待。另外，根据前人对该种在种加词的命名上的修改，我们将该新组合命名为Ephedra cheniae。 在调查该生物群中的买麻藤植物时，我们发现在部分化石类群中出现了前人没有记载过的新性状，比如在麻黄科类植物中发现了互生的分枝方式，并据此命名一个新的单种属Alloephedra xingxuei。为了探讨互生分枝这一性状对于麻黄科的分类意义，我们调查了国内外不少标本馆中的标本，并在野外做了取样统计。结果发现，在不少现代麻黄的枝条上都出现了不同程度的分枝发育不均衡，表现为在同一节上对生的两个分枝中一侧分枝能够正常发育而另一侧发育迟缓甚至不发育，这种不均衡的发育造成了在现代麻黄中出现了类似互生的分枝状况。在整理前人对麻黄分枝方式研究的基础上，结合我们对野外类群形态学性状的调查，我们认为由于在同一节上对生的两个分枝中一侧延迟或不发育而引起的类似互生的性状是较为广泛存在的，它不应该成为属一级的分类依据，而只能作为种一级的分类依据对待。因此我们将AHoephedra xingxuei转移到麻黄属中作为新组合Ephedra xingxuei处理。 除此之外，我们也发现了不少其他的买麻藤目化石标本，在对买麻藤目以往的化石记录了解以及对这些标本形态学性状把握的基础上，我们将这些新发现的化石标本放置在麻黄科麻黄属中作为新种对待，并根据其叶片以及苞片的特征分别将他们命名为披针叶麻黄（Ephedra lanceoleta）、裂叶麻黄（Ephedra divisa），卵叶麻黄（Ephedra ovata）以及双苞麻黄（Ephedra bibracta）。 与此同时，我们也发现了保存完好的被子植物的化石标本。该标本中具有5个离生的心皮、分枝方式兼具侧生和二叉分枝两种、并具有多裂的叶片。在辽西地区同时代发现的被子植物早期类型共有两个，分别是Archaefructus和Hyrcantha。其中前者具有许多个离生的螺旋状排列在可育枝的顶端1cm内的子房／心皮，而后者只有2-4个子房／心皮。在对我们新发现的化石标本与这两个被子植物的早期类型在叶片形态、分枝式样、果实大小、果实构成、果实排布、心 皮数目等形态学特征对比的基础上，我们认为新的化石标本描述了一个被子植物早期类群的新形态，并根据其具有五个心皮以及多裂的叶片的特征，命名为裂叶文采果Wentsaia divisa gen.＆sp. nov。 由于我们有幸能在辽西同时发现了买麻藤植物的化石标本和被子植物早期类型的标本，这就给了我们一个讨论二者在起源关系方面的机会。在对二者的营养器官特征、繁殖器官结构组成、繁殖器官性别构成以及对二者生活环境理解进行对比的基础上，我们认为，买麻藤目植物的早期类型与被子植物的早期类型之间存在相关性。但是就目前的证据而言，尚无法推测二者之间是否存在性状上的演化关系，而该问题的解决需要更多的化石证据的积累。

Atmospheric nutrient input to coastal areas: reducing the uncertainties

A significant fraction of the total nitrogen entering coastal and estuarine ecosystems along the eastern U.S. coast arises from atmospheric deposition; however, the exact role of atmospherically derived nitrogen in the decline of the health of coastal, estuarine, and inland waters is still uncertain. From the perspective of coastal ecosystem eutrophication, nitrogen compounds from the air, along with nitrogen from sewage, industrial effluent, and fertilizers, become a source of nutrients to the receiving ecosystem. Eutrophication, however, is only one of the detrimental impacts of the emission of nitrogen containing compounds to the atmosphere. Other adverse effects include the production of tropospheric ozone, acid deposition, and decreased visibility (photochemical smog). Assessments of the coastal eutrophication problem indicate that the atmospheric deposition loading is most important in the region extending from Albemarle/Parnlico Sounds to the Gulf of Maine; however, these assessments are based on model outputs supported by a meager amount of actual data. The data shortage is severe. The National Research Council specifically mentions the atmospheric role in its recent publication for the Committee on Environmental and Natural Resources, Priorities for Coastal Ecosystem Science (1994). It states that, "Problems associated with changes in the quantity and quality of inputs to coastal environments from runoff and atmospheric deposition are particularly important [to coastal ecosystem integrity]. These include nutrient loading from agriculture and fossil fuel combustion, habitat losses from eutrophication, widespread contamination by toxic materials, changes in riverborne sediment, and alteration of coastal hydrodynamics. "

Chemical contaminants in the coral Porites astreoides from southwest Puerto Rico

This report presents an initial characterization of chemical contamination in coral tissues (Porites astreoides) from southwest Puerto Rico. It is the second technical report from a project to characterize chemical contaminants and assess linkages between contamination and coral condition. The first report quantified chemical contaminants in sediments from southwest Puerto Rico. This document summarizes the analysis of nearly 150 chemical contaminants in coral tissues. Although only eight coral samples were collected, some observations can be made on the correlations between observed tissue and sediment contaminant concentrations. The concentrations of polycyclic aromatic hydrocarbons (PAHs), typically associated with petroleum spills and the combustion of fossil fuels, and polychlorinated biphenyls (PCBs) in the coral tissues were comparable to concentrations found in adjacent sediments. However, the concentration of a chemical contaminant (e.g., PAHs) in the coral tissues at a particular site was not a good predictor of what was in the adjacent sediments. In addition, the types of PAHs found in the coral tissues were somewhat different (higher ratios of alkylated PAHs) than in sediments. The levels of PCBs and DDT in coral tissues appeared higher just outside of Guanica Bay, and there was evidence of a downstream concentration gradient for these two contaminant classes. The trace elements copper, zinc and nickel were frequently detected in coral tissues, and the concentration in the corals was usually comparable to that found in adjacent sediments. Chromium was an exception in that it was not detected in any of the coral tissues analyzed. Additional work is needed to assess how spatial patterns in chemical contamination affect coral condition, abundance and distribution.

El Niño reconstructions and confirmation of a pan-Californian model via Radiolarian evidence

Radiolarian number and/or flux rates extracted from Holocene and fossil sediments are used to help detect the presence of, type of (weak or strong), and exact location of the depocenter under an El Niño. These data, along with known provenances of certain radiolarians, support an earlier model that suggests a weak El Niño is a northern and coupled expression of a more southerly strong component dominated by eastern tropical Pacific water underlain by California current and gyre water.

Neogene through Pleistocene paleoclimate of the Great Salt Lake region, northeastern Great Basin, USA

In a cooperative agreement between Amoco Production Company and the University of Arizona Geosciences Department, extensive data and resources associated with 15 deep wells drilled in the Great Salt Lake are currently on loan at the University of Arizona. Seismic data, electric and lithologic logs, cuttings and previously-prepared pollen slides will eventually permit a thorough study of both the tectonic and climatic history of the Great Salt Lake region. The preliminary study presented here concentrates on the Late Tertiary and Pleistocene climatic reconstruction of the eastern Great Basin through examination of fossil pollen.

MULTIPLE GENOTYPES OF MITOCHONDRIAL-DNA WITHIN A HORSE POPULATION FROM A SMALL REGION IN YUNNAN PROVINCE OF CHINA

mtDNA genotypes of six domestic horses (three adult short horses whose heights are under 1 m and three common domestic horses) from a small region of 15 km(2) in Malipo county of Yunnan province of China were investigated by the technique of restriction fragment length polymorphism (RFLP) with restriction endonucleases which recognize 6-bp sequences. An average of fragments for an individual was obtained. Unlike other domestic animals, this population of horses exhibits high mtDNA genetic diversity. Each of the six horses has a specific mtDNA genotype showing a pattern of multiple maternal origins, as suggested by fossil and literature records. We think the population of horses is an amazing seed-resource pool of horses and hence deserves to be paid more attention from the view of conservation genetics. However it is also remarkable that we did not find any typical mtDNA genetic markers which would discriminate between short horses and common domestic horses.

Molecular evolution of microcephalin, a gene determining human brain size

Microcephalin gene is one of the major players in regulating human brain development. It was reported that truncated mutations in this gene can cause primary microcephaly in humans with a brain size comparable with that of early hominids. We studied the m

Y-chromosome evidence of southern origin of the East Asian - Specific haplogroup O3-M122

The prehistoric peopling of East Asia by modern humans remains controversial with respect to early population migrations. Here, we present a systematic sampling and genetic screening of an East Asian-specific Y-chromosome haplogroup (O3-M122) in 2,332 individuals from diverse East Asian populations. Our results indicate that the O3-M122 lineage is dominant in East Asian populations, with an average frequency of 44.3%. The microsatellite data show that the O3-M122 haplotypes in southern East Asia are more diverse than those in northern East Asia, suggesting a southern origin of the O3-M122 mutation. It was estimated that the early northward migration of the O3-M122 lineages in East Asia occurred similar to 25,000-30,000 years ago, consistent with the fossil records of modern humans in East Asia.

Phylogenetic study of complete cytochrome b genes in musk deer (genus Moschus) using museum samples

As an endangered animal group, musk deer (genus Moschus) are not only a great concern of wildlife conservation, but also of special interest to evolutionary studies due to long-standing arguments on the taxonomic and phylogenetic associations in this group. Using museum samples, we sequenced complete mitochondrial cytochrome b genes (1140 bp) of all suggested species of musk deer in order to reconstruct their phylogenetic history through molecular information. Our results showed that the cytochrome b gene tree is rather robust and concurred for all the algorithms employed (parsimony, maximum likelihood, and distance methods). Further, the relative rate test indicated a constant sequence substitution rate among all the species, permitting the dating of divergence events by molecular clock. According to the molecular topology, M. moschiferus branched off the earliest from a common ancestor of musk deer (about 700,000 years ago); then followed the bifurcation forming the M. berezouskii lineage and the lineage clustering M. fuscus, M. chrysogaster, and M. leucogaster (around 370,000 years before present), interestingly the most recent speciation event in musk deer happened rather recently (140,000 years ago), which might have resulted from the diversified habitats and geographic barriers in southwest China caused by gigantic movements of the Qinghai-Tibetan Plateau in history. Combining the data of current distributions, fossil records, and molecular data of this study, we suggest that the historical dispersion of musk deer might be from north to south in China. Additionally, in our further analyses involving other pecora species, musk deer was strongly supported as a monophyletic group and a valid family in Artiodactyla, closely related to Cervidae. (C) 1999 Academic Press.

Phylogenetic relationships of five pika species (genus Ochotona) based on mitochondrial DNA restriction maps

Restriction site mapping of mitochondrial DNA (mtDNA) with 16 restriction endonucleases was used to examine the phylogenetic relationships of Ochotona cansus, O. huangensis, O. thibetana, O. curzoniae and O. erythrotis. A 1-kb length variation between O. erythrotis of subgenus Pika and other four species of subgenus Ochotona was observed, which may be a useful genetic marker for identifying the two subgenera. The phylogenetic tree constructed using PAUP based on 61 phylogenetically informative sites suggests that O. erythrotis diverged first, followed by O. cansus, while O. curzoniae and O. huangensis are sister taxa related to O. thibetana, The results indicate that both O. cansus and O. huangensis should be treated as independent species. If the base substitution rate of pikas mtDNA was 2% per million years, then the divergence time of the two subgenera, Pika and Ochotana, is about 8.8 Ma ago of late Miocence, middle Bao-dian of Chinese mammalian age, and the divergence of the four species in subgenus Ochotona would have occurred about 2.5 - 4.2 Ma ago, Yushean of Chinese mammalian age. This calculation appears to be substantiated by the fossil record.

Evolutionary trends of the mitochondrial lineage differentiation in species of genera Martes and Mustela

We compared partial sequences (402 bp) of the mitochondrial cytochrome b gene in 68 individuals of martens (Martes), weasels (Mustela) and their relatives from the Northern Hemisphere to identify the modes of geographic differentiation in each species. We then compared complete sequences (1140 bp) of the gene in 17 species of the family Mustelidae to know the spatial and temporal modes of speciation, constructing linearized trees with transversional substitutions for deeper lineage divergences and with transversions and transitions for younger lineages. Our data suggested that these lineages of Martes and Mustela differentiated in a stepwise fashion with five radiation stages from the generic divergences (stage I) to the intraspecific divergences (stage V), during the last 10 or 20 million years as the fossil evidence suggests. In the lineage of Martes, the first offshoots are of Martes flavigula, M. pennanti, and Gulo gulo (stage II), the second is M. foina (stage III), and the third are M. americana, M. martes, M. melampus, and M. zibellina (stage IV). The divergence of the lineages of Mustela is likely to have taken place concurrently with the radiations of the Martes. These divergence processes are attributable in part to the geographic allocation along the two continents, North America and Eurasia, as well as among peripheral insular domains, such as Taiwan and the Japanese Islands. In addition, the Eurasian continent itself was shown to have been involved in the species diversification in the martens and weasels.

A multi-locus phylogeny of Nectogalini shrews and influences of the paleoclimate on speciation and evolution

Nectogaline shrews are a major component of the small mammalian fauna of Europe and Asia, and are notable for their diverse ecology, including utilization of aquatic habitats. So far, molecular phylogenetic analyses including nectogaline species have been unable to infer a well-resolved, well-supported phylogeny, thus limiting the power of comparative evolutionary and ecological analyses of the group. Here, we employ Bayesian phylogenetic analyses of eight mitochondrial and three nuclear genes to infer the phylogenetic relationships of nectogaline shrews. We subsequently use this phylogeny to assess the genetic diversity within the genus Episoriculus, and determine whether adaptation to aquatic habitats evolved independently multiple times. Moreover, we both analyze the fossil record and employ Bayesian relaxed clock divergence dating analyses of DNA to assess the impact of historical global climate change on the biogeography of Nectogalini. We infer strong support for the polyphyly of the genus Episoriculus. We also find strong evidence that the ability to heavily utilize aquatic habitats evolved independently in both Neomys and Chimarrogale + Nectogale lineages. Our Bayesian molecular divergence analysis suggests that the early history of Nectogalini is characterized by a rapid radiation at the Miocene/Pliocene boundary, thus potentially explaining the lack of resolution at the base of the tree. Finally, we find evidence that nectogalines once inhabited northern latitudes, but the global cooling and desiccating events at the Miocene/Pliocene and Pliocene/Pleistocene boundaries and Pleistocene glaciation resulted in the migration of most Nectogalini lineages to their present day southern distribution. (C) 2010 Elsevier Inc. All rights reserved.

Status of the biodiversity of St. Martin's Island, Bay of Bengal, Bangladesh

A total of 234 species of fish have been recorded from the St Martin Island. Of which, 98 species are coral associated. The total number of recorded mollusc and crab species stands at 187 and 7 species respectively. A total of 66 coral species were recorded, of which 19 are fossil corals, 36 living corals and the rest are under 6 families of subclass Octocorallia (soft corals). A total of 14 species of algae have been recorded from the St. Martin's Island. There is an estimated amount of 1500 MT red sea weed biomass available around the St. Martin's Island. The island contains some of the most unique, benthic community associations in Bangladesh, not found anywhere else in the South Asian region. The unique marine communities have very high scientific value for research and monitoring and there are only a few examples worldwide, where coral-algal communities dominate rocky reefs. The economy of the island is based on fishing. It is estimated that, about 1650 MT of fish are caught annually. Over-exploitation of renewable marine and coastal resources (e.g., rocky reef fisheries, coral and shell extraction; removal of coastal vegetation from inter-tidal and sub-tidal habitats) is a major threat to this ecosystem. Destructive fishing practices, mainly the use of rock-weighted gill nets over the inshore boulder reefs is of prime aggravates. Proper implementation of the rules and regulation for Ecologically Critical Areas (ECA's), alternative livelihood for the local people and further research should be immediately taken for sustainable utilization and to save the rich biodiversity of the only coral island in Bangladesh.

Nutrient loading and eutrophication of coastal waters of the South Asian Seas: a scoping study

This study looked at nutrient pollution and how it is affecting coastal and marine ecosystems in Bangladesh, India, Maldives, Pakistan and Sri Lanka. Causes it addressed included: agricultural practices; aquaculture; domestic sewage; industrial actions; and the burning of fossil fuels.

Interactions between Building Integrated Photovoltaics and microclimate in urban environments

BIPV(Building Integrated Photovoltaics) has progressed in the past years and become an element to be considered in city planning. BIPV has influence on microclimate in urban environments and the performance of BIPV is also affected by urban climate. The effect of BIPV on urban microclimate can be summarized under the following four aspects. The change of absorptivity and emissivity from original building surface to PV will change urban radiation balance. After installation of PV, building cooling load will be reduced because of PV shading effect, so urban anthropogenic heat also decreases to some extent. Because PV can reduce carbon dioxide emissions which is one of the reasons for urban heat island, BIPV is useful to mitigate this phenomena. The anthropogenic heat will alter after using BIPV, because partial replacement of fossil fuel means to change sensible heat from fossil fuel to solar energy. Different urban microclimate may have various effects on BIPV performance that can be analyzed from two perspectives. Firstly, BIPV performance may decline with the increase of air temperature in densely built areas because many factors in urban areas cause higher temperature than that of the surrounding countryside. Secondly, the change of solar irradiance at the ground level under urban air pollution will lead to the variation of BIPV performance because total solar irradiance usually is reduced and each solar cell has a different spectral response characteristic. The thermal model and performance model of ventilated BIPV according to actual meteorologic data in Tianjin(China) are combined to predict PV temperature and power output in the city of Tianjin. Then, using dynamic building energy model, cooling load is calculated after BIPV installation. The calculation made based in Tianjin shows that it is necessary to pay attention to and further analyze interaction between them to decrease urban pollution, improve BIPV Performance and reduce colling load. Copyright © 2005 by ASME.