Weddellite in a marine gastropod and in antarctic sediments

The calcium oxalate dihydrate mineral, weddellite, has been identified in a microarchitectural component of the gizzard plates from the deepwater gastropod Scaphander cylindrellus. This is the first indication of nonpathologic precipitation of this mineral by an animal species. A new occurrence of weddellite in sediments from the Weddell Sea, Antarctica, is also reported, lending support to the earlier interpretation that the mineral is an authigenic constituent of the sediments in this area.     

Temperature-dependent alterations in host use drive rapid range expansion in a butterfly

Responses of species to climate change are extremely variable, perhaps because of climate-related changes to interactions among species. We show that temperature-related changes in the dependence of the butterfly Aricia agestis on different larval host plants have facilitated rapid range expansion. Historically, the butterfly was largely restricted to a single plant species, Helianthemum nummularium, but recent warmer conditions have enabled the butterfly to increasingly use the more widespread plant species Geranium molle. This has resulted in a substantial increase in available habitat and rapid range expansion by the butterfly (79 kilometers northward in Britain in 20 years). Interactions among species are often seen as constraints on species' responses to climate change, but we show that temperature-dependent changes to interspecific interactions can also facilitate change.     

A theory of diversity equilibrium and morphological evolution

If the world can only support a finite amount of biomass, species might be added over time, with a decrease in population size of an average species. Population sizes of species will decrease to the extent that stochastic events eliminate species as fast as others appear, yielding an equilibrium. A resource diversity control of niche subdivision is therefore not needed to generate an equilibrium number of species. Morphological evolution may decelerate over time for similar reasons.     

Phanerozoic Earth system evolution and marine biodiversity

The Phanerozoic fossil record of marine animal diversity covaries with the amount of marine sedimentary rock. The extent to which this covariation reflects a geologically controlled sampling bias remains unknown. We show that Phanerozoic records of seawater chemistry and continental flooding contain information on the diversity of marine animals that is independent of sedimentary rock quantity and sampling. Interrelationships among variables suggest long-term interactions among continental flooding, sulfur and carbon cycling, and macroevolution. Thus, mutual responses to interacting Earth systems, not sampling biases, explain much of the observed covariation between Phanerozoic patterns of sedimentation and fossil biodiversity. Linkages between biodiversity and environmental records likely reflect complex biotic responses to changing ocean redox conditions and long-term sea-level fluctuations driven by plate tectonics.     

基于GIS的禽流感发生格局研究

    基于GIS空间数据处理技术,综合风险评估的理论和方法探询我国禽流感发生的风险格局.结果表明,我国禽流感疫情在经过2004年以来的综合防治以及2005年以来的免疫政策,目前疫情发生强度虽有所减弱,但疫情扩散和病毒变异风险依然存在:①我国以散养和小规模养殖模式为主体的养殖结构使禽流感发生的接触和暴露风险增大,特别是在候鸟迁徙区域的西南流域温地、西藏流域湿地、新疆流域湿地、甘蒙流域湿地、长江流域湿地以及黑龙江流域湿地,这些湿地区域在候鸟迁徙、带毒扩散上的廊道作用将逐渐显现;②目前我国禽流感疫情发生的聚集型态势明显.区域尺度疫点格局分析表明,在云南、辽宁、新疆、内蒙、广西和西藏的禽流感疫情发生的空间相关性显著,为聚集型分布,格局分析同时表明,目前我国禽流感发生已经形成了以西南一华南流域湿地、长江流域湿地、西藏流域湿地、新疆流域湿地、甘蒙流域湿地和黑龙江流域湿地等为中心的多点位发生态势;③全国尺度疫点格局分析表明,我国2004--2006年禽流感发生疫点的空间分布为聚集型,R统计特征值为0.43126(0.05水平),标准化ZR为7.69399,95%的置信区间内说明我国目前疫情已经跨越了零星发生的态势,聚集分布的空间特征使我国禽流感在一定时间段内复发成为可能.     

Speciation and stasis in marine ostracoda: climatic modulation of evolution

Morphologic and paleozoogeographic analysis of Cenozoic marine Ostracoda from the Atlantic, Caribbean, and Pacific indicates that climatic change modulates evolution by disrupting long-term stasis and catalyzing speciation during sustained, unidirectional climatic transitions and, conversely, by maintaining morphologic stasis during rapid, high-frequency climatic oscillations. In the middle Pliocene, 4 to 3 million years ago, at least six new species of Puriana suddenly appeared as the Isthmus of Panama closed, changing oceanographic circulation and global climate. Since then morphologic stasis has characterized ancestral and descendant species during many glacial-interglacial cycles. The frequency and duration of climatic events have more impact on ostracode evolution than the magnitude of climatic changes.     

Biological bulldozers and the evolution of marine benthic communities

During the Phanerozoic, the diversity of immobile suspension feeders living on the surface of soft substrata (ISOSS) declined significantly. Immobile taxa on hard surfaces and mobile taxa diversified. Extinction rates of ISOSS were significantly greater than in other benthos. These changes in the structure of benthic communities are attributed to increased biological disturbance of the sediment (bioturbation) by diversifying deposit feeders.     

合肥市建设扩张与生态格局时空演变特征分析

近20年来合肥市城市建设迅速发展,对生态环境稳定性产生一定影响。以景观指数为基础解析1995—2016年合肥市景观格局,并在此基础上计算反映建设用地与耕地景观时空演变特征的景观梯度及其动态度,研究城市建设对生态环境的影响。结果表明,20年来合肥市城市化进程致使建设用地面积增加85.68%,超过18.41%耕地流失,景观破碎化程度增加,形状复杂化,城市扩张导致城市生态环境脆弱性增加。近20年间城区以旧城区为中心持续向四周扩展,2005年之前主要往西南方向扩展,对其生态环境产生负面影响;2005年之后南部、北部扩展幅度较大,南、北部郊区的快速建设影响着其生态系统的稳定性;2010年之后外围城镇扩展速度增加,致使城区外围生态环境稳定性下降。城市扩张致使生态环境的胁迫作用持续增加,在城市化进程中应采取适当的措施改善城市建设与生态平衡的关系,促进可持续发展的城市建设。     

基于GIS的松树萎蔫病发生格局研究

通过GIS对发病信息的空间定位以及发病林型几何质心的挖掘,对空间点(单元)发病属性数据建立距离矩阵,利用空间自相关性指数研究探询安徽滁州地区松树萎蔫病发生的空间扩散机制,结果表明:松树萎蔫病在安徽滁州和马鞍山地区的发病率从0.18%到46%不等,严重发病的区域主要集中在明光县管店林业总厂及其相邻的鲁山林厂和老嘉山林场,发病率都在40%～46%;其次为马鞍山地区的横山林场及其附近的薛津镇.在安徽滁州地区和马鞍山地区松树萎蔫病的发生和扩散有适宜的生境条件,该地区松材线虫易感植被集聚分布的特点使松树萎蔫病持续发生和蔓延成为可能.空间自相关性的分析发现,松树萎蔫病在该区域内发病的Moran's Ⅰ的空间自相关指数高达74.86%(0.05水平检验),推断在安徽滁州和马鞍山地区1316个以林型为发病单元的发病点的分布格局为高度聚集型,同时也说明松树萎蔫病在安徽滁州和马鞍山地区的发生具有一定强度的传染性.     

滨海新区填海造陆的地形地貌环境演变影响分析

填海造陆对海岸环境的影响主要体现在改变海岸线长度与形态及直接吹填沙导致近海海底地形地貌变化[1],这些变化影响着海岸带规划管理和可持续发展,具有重要的理论和现实意义。本文利用滨海新区遥感影像及其海图资料,对该区域近30年海岸线变迁、围填海演变及海底地形信息进行了提取,并对其具体进程和驱动因素进行了研究。研究表明：30年间,滨海新区海岸线变迁是向海洋推进,且推进的趋势越来越明显,岸线长度增长趋势愈发明显,变迁面积较大。针对填海造陆引起围堤基底冲刷问题,笔者提出了可供参考的解决方案。     

Sedimentary environments in a marine marsh

Several foraminiferal assemblages are recognized in Spartina-Salicornia marshes along the Pacific and Gulf of Mexico coasts. Continuous recordings in one Pacific marsh show considerable diurnal and seasonal variation in pH, oxygen, water temperature, and salinity. This is related to tidal flushing, air temperature variations, sunlight duration, and marsh plant metabolism.     

Predator-induced defense in a marine bryozoan

Laboratory experiments showed that predation by both trophically specialized and generalized nudibranch species triggers rapid induction of defensive spines in the bryozoan Membranipora membranacea. Spines effectively control the pattern and extent of intracolony mortality caused by nudibranch predation. Previously found only in plants, rotifers, and cladocerans, consumer-induced defenses may be widespread among clone-forming or colonial taxa exposed to nonfatal encounters with predators.     

Encystment discovered in a marine copepod

It has been believed that marine crustacea do not encyst as adults. The benthic copepod Heteropsyllus nunni has been found to encyst in intertidal sands in the summer; free-living forms are abundant in the winter. A unique platelike structure on the cephalothorax is thought to be the site of cyst formation.     

Convergent morphological evolution detected by studying proteins of tree frogs in the Hyla eximia species group

Protein studies have uncovered an apparent case of convergent evolution among North American tree frogs. The species Hyla eximia and Hyla regilla are so similar in external morphology that the "wrightorum" subspecies is assigned by some authorities to H. eximia and by others to H. regilla. Yet microcomplement fixation experiments show that "wrightorum" albumin, though virtually indistinguishable from authentic H. eximia albumin, differs as much from H. regilla albumin as from albumins of species outside the genus Hyla, such as Acris crepitans. The morphological resemblance of "wrightorum" to H. regilla is thus probably due to convergence.     

Role of the gastropod shell and operculum in inhibiting predation by fishes

In contrast to the diets of other cottid fishes and most teleosts, the diet of Asemichthys taylori is dominated by gastropod mollusks. Access to this underused prey appears to be made possible by morphological speializations of the neurocanium that allow Asemichthys to puncture the shells of its prey during mastication. Unpunched, the shell and operculum act as a barrier to digestion; more than 40% of the unpunched gastropods emerged alive in the feces. Asemichthys adjusted its punching behavior in an apparently adaptive way; other prey lacking such barriers to digestion were rarely punched. The ability of some shelled invertebrates to avoid digestion may make them less desirable as prey for many fishes that cannot masticate this kind of prey. The ability of shelled mollusks to survive in the digestive tracts of vertebrates may provide a dispersal mechanism for otherwise sedentary species.     

Natal homing in a marine fish metapopulation

Identifying natal origins of marine fishes is challenging because of difficulties in conducting mark-recapture studies in marine systems. We used natural geochemical signatures in otoliths (ear bones) to determine natal sources in weakfish (Cynoscion regalis), an estuarine-spawning marine fish, in eastern North America. Spawning site fidelity ranged from 60 to 81%, comparable to estimates of natal homing in birds and anadromous fishes. These data were in contrast to genetic analyses of population structure in weakfish. Our findings highlight the need for consideration of spatial processes in fisheries models and have implications for the design of marine reserves in coastal regions.     

Local selection and latitudinal variation in a marine predator-prey interaction

Although pairs of species often interact over broad geographic ranges, few studies have explored how interactions vary across these large spatial scales. Surveys along 1500 kilometers of the Pacific coast of North America documented marked variation in the frequency of predation by the snail Nucella canaliculata on the intertidal mussel Mytilus californianus. Laboratory rearing experiments suggest that regional differences in drilling behavior have a genetic basis, and mitochondrial sequence variation confirms that gene flow is low among these snail populations. Marine communities separated by hundreds of kilometers may have intrinsically different dynamics, with interactions shaped by restricted gene flow and spatially varying selection.     

Phase evolution in a Kondo-correlated system

We measured the phase evolution of electrons as they traverse a quantum dot (QD) formed in a two-dimensional electron gas that serves as a localized spin. The traversal phase, determined by embedding the QD in a double path electron interferometer and measuring the quantum interference of the electron wave functions manifested by conductance oscillation as a function of a weak magnetic field, evolved by pi radians, a range twice as large as theoretically predicted. As the correlation weakened, a gradual transition to the familiar phase evolution of a QD was observed. The specific phase evolution observed is highly sensitive to the onset of Kondo correlation, possibly serving as an alternative fingerprint of the Kondo effect.     

Predator-prey role reversal in a marine benthic ecosystem

Two closely located islands on the west coast of South Africa support widely different benthic communities. The biota at Malgas Island is dominated by seaweeds and by rock lobsters that consume settling mussels, thereby preventing the establishment of the mussels. They also prey on whelks, although one speces, Burnupena papyracea, is protected from predation by a commensal bryozoan that covers its shell. Marcus Island has extensive mussel beds, but rock lobsters and seaweeds are virtually absent; whelks (mostly Burnupena spp.) occur at high densities. Rock lobsters transferred to Marcus Island were overwhelmed and consumed by the whelks, reversing the normal predatorprey relation between the two species. These two contrasting communities persisted during 4 years and may represent multiple states of the same ecosystem. This effective change of roles between a prey species and its chief predator may provide an intrinsic mechanism to maintain these states following the initial exclusion of the predator.