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72.
KAZUNORI YAMAHIRA TAKESHI NISHIDA † AISAKU ARAKAWA ‡ HIROAKI IWAISAKI ‡ 《Biological journal of the Linnean Society. Linnean Society of London》2009,96(4):867-874
Variation in the number of abdominal vs. caudal vertebrae is an important source of morphological diversification of fish. It is not clear, however, whether abdominal and caudal regions evolve independently. Regressions of offspring on parents demonstrated substantial additive genetic variation within populations, i.e. heritability, in both abdominal and caudal vertebral numbers of the medaka ( Oryzias latipes ). However, the heritability of caudal vertebrae tended to be smaller than that of abdominal vertebrae in some estimations, suggesting that abdominal and caudal regions are controlled by separate developmental modules. Furthermore, genetic correlation between abdominal and caudal vertebral numbers, estimated using full-sib family means, was negative but weak, supporting independent evolution. In addition, substantial genetic differentiation among populations was demonstrated in abdominal vertebral numbers, but not in caudal numbers. These results support our view that Jordan's rule, a geographical tendency for fish from higher latitudes to have more vertebrae, in this fish reflects local adaptations of abdominal vertebral numbers. In contrast, the low heritability of caudal vertebrae may reflect the intrinsic invariability of genes associated with a change in caudal vertebral numbers. This genetic constraint may have restricted morphological diversification of not only the medaka, but also the Order Beloniformes as a whole. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 867–874. 相似文献
73.
Abstract. 1. In insect communities on fermented tree sap, agonistic interactions occur frequently among the component species. This study examined the effects of such interference competition on community structure and species co-occurrence on a spatio-temporally small scale.
2. Experimental removal of giant hornets ( Vespa mandarinia ), one of the most dominant species, showed no effect on either species richness or total abundance of the remaining insects. Significant increases in abundance were detected for five out of 19 taxa: V. ducalis , V. crabro , Lasius japonicus , Cryptarcha lewisi , and a group of micro sap beetles ( Epuraea spp., Haptoncus spp., and Haptoncurina spp.).
3. Behavioural observations indicated that interference did not alter the staying time at a patch (an exuding spot on a tree) for V. mandarinia , Rhomborrhina japonica , and Neope goschkevitschii . Interference-mediated departure from a patch was less frequent than departure without interference for all nine species observed, except for R. japonica . These behavioural contexts varied yearly for several species.
4. These results suggest that interference competition is a minor determinant of overall community structure, despite its conspicuousness. This weak effect of interference may be attributed to the short stay of dominant species and to individual behavioural responses, such as competitor avoidance. The variable influence of interference might be related to differences in species attributes, such as dominance hierarchies. 相似文献
2. Experimental removal of giant hornets ( Vespa mandarinia ), one of the most dominant species, showed no effect on either species richness or total abundance of the remaining insects. Significant increases in abundance were detected for five out of 19 taxa: V. ducalis , V. crabro , Lasius japonicus , Cryptarcha lewisi , and a group of micro sap beetles ( Epuraea spp., Haptoncus spp., and Haptoncurina spp.).
3. Behavioural observations indicated that interference did not alter the staying time at a patch (an exuding spot on a tree) for V. mandarinia , Rhomborrhina japonica , and Neope goschkevitschii . Interference-mediated departure from a patch was less frequent than departure without interference for all nine species observed, except for R. japonica . These behavioural contexts varied yearly for several species.
4. These results suggest that interference competition is a minor determinant of overall community structure, despite its conspicuousness. This weak effect of interference may be attributed to the short stay of dominant species and to individual behavioural responses, such as competitor avoidance. The variable influence of interference might be related to differences in species attributes, such as dominance hierarchies. 相似文献
74.
Wetland mitigation and compensation: Canadian experience 总被引:3,自引:0,他引:3
Since Canada’s accession to the Ramsar Convention on Wetlands in 1981, the nation’s commitment to wetland conservation and
management has increased significantly. This includes the adoption of one of the World’s first national wetland conservation
policies by the Government of Canada, and the adoption of complementary policy and legislative initiatives by most of the
13 provincial and territorial jurisdictions. Numerous habitat ‘no net loss’ and environmental assessment policies, regulations
and guidelines for incorporating mitigation processes into development decisions affecting wetland resources are used throughout
Canada. The governments of Canada and six provinces have so far adopted wetland mitigation measures. These are in addition
to comprehensive wetland fish and wildlife habitat initiatives, such as the species and habitat joint ventures delivered in
Canada through the North American Waterfowl Management Plan by all jurisdictions and numerous non-government partners. This
paper examines the current policies, regulations and programs, as well as past implementation experience with wetland mitigation
and compensation in Canada. 相似文献
75.
Shifts in climate regime have provoked substantial trophic‐ and species‐dependent changes within ecosystems. With growing concerns of present global warming, we examined potential lake ecosystem responses, natural hierarchy responses (i.e. immediate responses at lower system levels as opposed to delayed responses at higher system levels), and possible shifts among abiotic (physics, nutrients) and biotic (phytoplankton, zooplankton) system components. Specifically, we analyzed decadal data collected from Müggelsee, a lake in Berlin, Germany, for climate‐induced abiotic and biotic changes, their timing and type, and classified them as abrupt permanent, gradual permanent, abrupt temporary, or monotonic. We further categorized variable changes as a function of system hierarchy, including lake physics (ice, temperature, stratification), nutrients (phosphorus, nitrogen, silicate), plankton, and levels of integration (i.e. species, taxonomic groups, and total plankton). Contrary to current theory, data suggest abrupt responses did not occur in a hierarchy‐dependent manner, nor was a clear pattern observed among functional system‐based categories. Abrupt permanent changes were the most prominent response pattern observed, suggesting they may be driven by large‐scale climatic oscillations and by surpassed thresholds, as noted in previous case studies. Gradual changes coincided with affected abiotic parameters spanning an expansive time range; for example, climatic effects in spring preceded changes in nutrient limitation. Variables displaying no long‐term changes pointed to compensation processes caused by, e.g., simultaneously acting forces of warming trends and climate‐independent changes in trophic state. Nevertheless, the complexity of response patterns at the single system level manifested clear chronological regime shifts in abiotic and biotic parameters in spring and, to a lesser extent, in summer. With regard to projected global warming, the majority of currently unaffected system levels may face impending thermal thresholds, achievement of which would result in an accelerated shift in ecosystem state. 相似文献
76.
目的:研究哺乳动物代谢型谷氨酸受体(mGluR)亚家族捕蝇夹结构模块(VFTM)的系统进化形式,确定其VFTM的功能分化决定位点。方法:通过基于系统进化的功能歧化分析,根据贝叶斯模型计算VFTM的选择性限制位点,推测功能分化决定位点。结果:mGluR亚家族VFTM的祖先通过2次基因复制,在不同的氨基酸位点进行选择性限制,形成3组不同的mGluR亚家族成员。结论:不同功能分化决定位点的选择性功能歧化塑造了mGluR亚家族VFTM的结构与功能,为进一步研究mGluR亚家族的激活机制奠定了基础。 相似文献
77.
We review winner-loser models, the currently popular explanation for the occurrence of linear dominance hierarchies, via a
three-part approach. (1) We isolate the two most significant components of the mathematical formulation of three of the most
widely-cited models and rigorously evaluate the components’ predictions against data collected on hierarchy formation in groups
of hens. (2) We evaluate the experimental support in the literature for the basic assumptions contained in winner-loser models.
(3) We apply new techniques to the hen data to uncover several behavioral dynamics of hierarchy formation not previously described.
The mathematical formulations of these models do not show satisfactory agreement with the hen data, and key model assumptions
have either little or no conclusive support from experimental findings in the literature. In agreement with the latest experimental
results concerning social cognition, the new behavioral dynamics of hierarchy formation discovered in the hen data suggest
that members of groups are intensely aware both of their own interactions as well as interactions occurring among other members of their group. We suggest that
more adequate models of hierarchy formation should be based upon behavioral dynamics that reflect more sophisticated levels
of social cognition. 相似文献
78.
The cellulosome complex has evolved to degrade plant cell walls and, as such, combines tenacious binding to cellulose with
diverse catalytic activities against amorphous and crystalline cellulose. Cellulolytic microorganisms provide an extensive
selection of domains; those with affinity for cellulose, cohesins and their dockerin binding partners that define cellulosome
stoichiometry and architecture, and a range of catalytic activities against carbohydrates. These robust domains provide the
building blocks for molecular design. This review examines how protein modules derived from the cellulosome have been incorporated
into chimaeric proteins to provide biosynthetic tools for research and industry. These applications include affinity tags
for protein purification, and non-chemical methods for immobilisation and presentation of recombinant protein domains on cellulosic
substrates. Cellulosomal architecture provides a paradigm for design of enzymatic complexes that synergistically combine multiple
catalytic subunits to achieve higher specific activity than would be obtained using free enzymes. Multimeric enzymatic complexes
may have industrial applications of relevance for an emerging carbon economy. Biocatalysis will lead to more efficient utilisation
of renewable carbon-fixing energy sources with the added benefits of reducing chemical waste streams and reliance on petroleum. 相似文献
79.
80.
Marc-Thorsten Hütt Marcus Kaiser Claus C. Hilgetag 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1653)
The understanding of neural activity patterns is fundamentally linked to an understanding of how the brain''s network architecture shapes dynamical processes. Established approaches rely mostly on deviations of a given network from certain classes of random graphs. Hypotheses about the supposed role of prominent topological features (for instance, the roles of modularity, network motifs or hierarchical network organization) are derived from these deviations. An alternative strategy could be to study deviations of network architectures from regular graphs (rings and lattices) and consider the implications of such deviations for self-organized dynamic patterns on the network. Following this strategy, we draw on the theory of spatio-temporal pattern formation and propose a novel perspective for analysing dynamics on networks, by evaluating how the self-organized dynamics are confined by network architecture to a small set of permissible collective states. In particular, we discuss the role of prominent topological features of brain connectivity, such as hubs, modules and hierarchy, in shaping activity patterns. We illustrate the notion of network-guided pattern formation with numerical simulations and outline how it can facilitate the understanding of neural dynamics. 相似文献