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41.
MAGALIE CASTELIN JOSIE LAMBOURDIERE MARIE‐CATHERINE BOISSELIER PIERRE LOZOUET ARNAUD COULOUX CORINNE CRUAUD SARAH SAMADI 《Biological journal of the Linnean Society. Linnean Society of London》2010,100(2):420-438
The seamounts chain offers a set of fragmented habitats in which species with poor dispersive ability may undergo divergence in allopatry. Such a scenario may explain the endemism often described on seamounts. In gastropods, it is possible to infer the mode of development of a species from the morphology of its larval shell. Accordingly, we examine the population genetics of several caenogastropods from the Norfolk and Lord Howe seamounts (south‐west Pacific) with contrasting modes of larval development. A prerequisite to our study was to clarify the taxonomic framework. The species delimitation was ruled using an integrative approach, based on both morphological and molecular evidence. Molecular data indicate an unexpected taxonomic diversity within the existing species names. Both the clarification of the taxonomic framework and the importance of the sampling effort allow us to confidently detect cryptic diversity and micro‐endemism. These results are discussed in relation to the dispersive capacities of the organisms. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 420–438. 相似文献
42.
43.
T.J.B. Carruthers W.C. Dennison G.A. Kendrick M. Waycott D.I. Walker M.L. Cambridge 《Journal of experimental marine biology and ecology》2007,350(1-2):21-45
South–west Australia contains extensive seagrass meadows along 2,500 km of coastline from the shallow subtidal to 50+ m water depths, and in many of the 51 bar-built estuaries along the coast. There are geomorphological differences between the south and west coasts that result in different patterns of swell exposure influencing the processes that structure seagrass habitats. In this paper, ‘sheltered’, ‘exposed’ and ‘estuarine’ seagrass habitat types are defined for south–west Australia to synthesize processes influencing seagrass communities. Sheltered habitats in south–west Australia are characterized by high light, low to moderate water motion and sporadic disturbance from storms, making them ideal habitats for a diversity of seagrass assemblages. Exposed seagrass habitats are characterized by the presence of strong and consistent ocean swells (3–8 m), predominantly from the south or south–west and seagrasses exhibit a suite of adaptive traits to survive the effects of exposure to ocean swell and associated sand movement. These include morphological features such as heavy fiber reinforcement to strengthen the aboveground stems or leaves, deep vertical rhizomes and life history traits such as rapid growth and high seed set. Within estuarine habitats highly dynamic seagrass communities are the result of fluctuating annual cycles in temperature, light and salinity. Compared to global seagrass meadows, coastal south–west Australian seagrass habitats experience high light, low nutrients and high water movement. Despite these differences, similarities with other regions do exist and here we place the habitats of south–west Australia into a global context using comparative data. The wide array of morphology and life history traits displayed among seagrass species of south–west Australia are presented in a conceptual model including habitat type, physical stressors and seagrass responses. The combination of adaptations to the habitats and processes that define them make south–west Australia a region where there is an unusually high number of co-occurring seagrass species, the highest in the world for a temperate environment (19 species), and approaching the species diversity of many tropical environments. Linking aspects of seagrass habitat, physical aspects of the environment and seagrass life history provides a context for applying knowledge gained from seagrasses in south–west Australia to other coastal ecosystems throughout the world. 相似文献
44.
Luzyanina T Mrusek S Edwards JT Roose D Ehl S Bocharov G 《Journal of mathematical biology》2007,54(1):57-89
CFSE based tracking of the lymphocyte proliferation using flow cytometry is a powerful experimental technique in immunology
allowing for the tracing of labelled cell populations over time in terms of the number of divisions cells undergone. Interpretation
and understanding of such population data can be greatly improved through the use of mathematical modelling. We apply a heterogenous
linear compartmental model, described by a system of ordinary differential equations similar to those proposed by Kendall.
This model allows division number-dependent rates of cell proliferation and death and describes the rate of changes in the
numbers of cells having undergone j divisions. The experimental data set that we specifically analyze specifies the following characteristics of the kinetics
of PHA-induced human T lymphocyte proliferation assay in vitroL (1) the total number of live cells, (2) the total number of
dead but not disintegrated cells and (3) the number of cells divided j times. Following the maximum likelihood approach for data fitting, we estimate the model parameters which, in particular,
present the CTL birth- and death rate “functions”. It is the first study of CFSE labelling data which convincingly shows that
the lymphocyte proliferation and death both in vitro and in vivo are division number dependent. For the first time, the confidence
in the estimated parameter values is analyzed by comparing three major methods: the technique based on the variance–covariance
matrix, the profile-likelihood-based approach and the bootstrap technique. We compare results and performance of these methods
with respect to their robustness and computational cost. We show that for evaluating mathematical models of differing complexity
the information-theoretic approach, based upon indicators measuring the information loss for a particular model (Kullback–Leibler
information), provides a consistent basis. We specifically discuss methodological and computational difficulties in parameter
identification with CFSE data, e.g. the loss of confidence in the parameter estimates starting around the sixth division.
Overall, our study suggests that the heterogeneity inherent in cell kinetics should be explicitly incorporated into the structure
of mathematical models.
相似文献
45.
GRANT R. SINGLETON† COLIN R. TANN§ CHARLES J. KREBS†‡ 《Journal of Applied Ecology》2007,44(3):644-652
46.
47.
Carol A. Shearer Enrique Descals Brigitte Kohlmeyer Jan Kohlmeyer Ludmila Marvanová David Padgett David Porter Huzefa A. Raja John P. Schmit Holly A. Thorton Hermann Voglymayr 《Biodiversity and Conservation》2007,16(1):49-67
Fungal biodiversity in freshwater, brackish and marine habitats was estimated based on reports in the literature. The taxonomic
groups treated were those with species commonly found on submerged substrates in aquatic habitats: Ascomycetes (exclusive of yeasts), Basidiomycetes, Chytridiomycetes, and the non-fungal Saprolegniales in the Class Oomycetes. Based on presence/absence data for a large number and variety of aquatic habitats, about 3,000 fungal species and 138 saprolegnialean
species have been reported from aquatic habitats. The greatest number of taxa comprise the Ascomycetes, including mitosporic taxa, and Chytridiomycetes. Taxa of Basidiomycetes are, for the most part, excluded from aquatic habitats. The greatest biodiversity for all groups occurs in temperate areas,
followed by Asian tropical areas. This pattern may be an artifact of the location of most of the sampling effort. The least
sampled geographic areas include Africa, Australia, China, South America and boreal and tropical regions worldwide. Some species
overlap occurs among terrestrial and freshwater taxa but little species overlap occurs among freshwater and marine taxa. We
predict that many species remain to be discovered in aquatic habitats given the few taxonomic specialists studying these fungi,
the few substrate types studied intensively, and the vast geographical area not yet sampled. 相似文献
48.
Freshwater finfish species richness and level of endemism in East, and South and South‐East Asia that included 17 nations were studied using available databases, and included nation‐wise distribution, habitat types, and conservation status. The number of endemic finfish species in the region was 559, belonging to 47 families. Families Cyprinidae and Balitoridae accounted for 43.5% and 16.2% of the total number of endemic species in the region, respectively, followed by Sisoridae (25), Gobiidae (20), Melanotaeniidae (19), and Bagridae (16), and the other 41 families had at least one endemic species. Nation‐wise the most number of endemic freshwater finfish species occur in India (191), followed by China (88), Indonesia (84), and Myanmar (60). In India, the endemic species accounted for 26.4% of the native freshwater fish fauna, followed by South Korea (16.9%), the Philippines, (16.3%) and Myanmar (15.7%). Statistically significant relationships discerned between the number of indigenous and endemic species richness to land area (Xla in 103 km2) of the nations in the region were, Yin = 218.961 Ln(Xla) – 843.1 (R2 = 0.735; P < 0.001) and Ye = 28.445 Ln Xla?134.47 (R2 = 0.534; P < 0.01), respectively, and between indigenous and endemic species richness was Ye = 0.079Xn? 1.558 (R2 = 0.235; P < 0.05). The overall conservation status of endemic finfish in Asia was satisfactory in that only 92 species were in some state of vulnerability, of which 37 species (6.6%) are endangered or critically endangered. However, the bulk of these species (83.7%) were cave‐ and or lake‐dwelling fish. However, nation‐wise, the endemic freshwater finfish fauna of the Philippines and Sri Lanka, based on the imperilment index, were found to be in a highly vulnerable state. Among river basins, the Mekong Basin had the highest number of endemic species (31.3%). The discrepancies between databases are highlighted and the need to consolidate information among databases is discussed. It is suggested that the Mekong Basin be considered as a biodiversity hotspot, and appropriate management strategies be introduced in this regard. 相似文献
49.
Changes of traditional agrarian landscapes and their conservation implications: a case study of butterflies in Romania 总被引:2,自引:0,他引:2
Global biodiversity is decreasing as a result of human activities. In many parts of the world, this decrease is due to the destruction of natural habitats. The European perspective is different. Here, traditional agricultural landscapes developed into species-rich habitats. However, the European biodiversity heritage is strongly endangered. One of the countries where this biodiversity is best preserved is Romania. We analyse the possible changes in Romania's land-use patterns and their possible benefits and hazards with respect to biodiversity. As model group, we used butterflies, whose habitat requirements are well understood. We determined the ecological importance of different land-use types for the conservation of butterflies, underlining the special importance of Romania's semi-natural grasslands for nature conservation. We found that increasing modern agriculture and abandonment of less productive sites both affect biodiversity negatively — the former immediately and the latter after a lag phase of several years. These perspectives are discussed in the light of the integration of Romania into the European Union. 相似文献
50.
Filipa Loureiro Luís Miguel Rosalino David W. Macdonald Margarida Santos-Reis 《Ecological Research》2007,22(5):837-844
Movement is the process by which individual organisms are displaced over time to eat, reproduce and defend resources. Fractal
analysis is a technique used to study animal movement that measures spatial complexity of path tortuosity; here, we apply
it to characterize the movement patterns of the Eurasian badger (Meles meles) in a Mediterranean landscape. We calculated path tortuosity overall and seasonally, and for individuals of different sexes
and social groups. The influence of variables related to badgers’ resources (food, shelter, water), human infra-structures
and weather conditions were analysed with respect to the tortuosity of each badger’s path. A total of 55 search paths from
six badgers were considered for this study. Although badgers generally displayed convoluted movement, there were two exceptions:
(a) males overall and (b) all badgers in summer; for both, movements had a lower fractal value, i.e. were less tortuous. The
convoluted movement pattern generally observed is probably adapted to the clumped distribution of food in the study area.
Nevertheless, our results suggest that the use of dens and latrines were the principal determinants of tortuosity of badgers’
paths while foraging. 相似文献