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1.
Evidence is presented that, contrary to common scientific “belief”, larva digeneans have profound effects on various components at various levels of the littoral marine ecosystem. Their ecological capacity includes: —Reduction of the breeding potential of host populations by “parasitic castration”; —Structural modification of host populations by generation of erratic growth patterns, size-class differential mortality and “negative growth”; —Induction of host-population mortality and control by increased susceptibility to environmental stress; —Induction of changes in community structure by removal of hosts from their normal trophic levels; —Interference with major energy-flow pathways by precocious removal of hosts from their normal food-web position; —Interference with host-biomass, production and turnover-rate estimations by by-passing of hostassimilated energy; —Interference with predator-prey systems by affecting either component(s) of such systems.The notorious neglect of these factors by marine ecologists and, even more, their total unawareness of the effects these factors produce, raise serious doubts about the validity of marine ecological data and concepts. For the parasitologist, on the other hand, the study of ecological aspects of marine parasite (digenean) biology may open new avenues of research. With a true synthesis of both scientific disciplines, we may eventually arrive at a point where “more complete knowledge of life cycles will permit more intelligent and more effective regulatory methods, the reduction of morbidity, the advancement of health, and the conservation of natural resources.”The latter statement has not been cited from a recent issue of a scientific journal; it has been written down as long as 46 (!) years ago by one of the most outstanding investigators of marine digenean life cycles—Horace W. Stunkard (1940, p 15), but has lost nothing of its actuality. It is hoped that Stunkard's far-sighted words might encourage parasitologists to devote some of their scientific power and skill to the study of marine ecoparasitological problems—for the sake of a better understanding of ecological processes and to the benefit of the endangered marine life.  相似文献   

2.
The rainbow smelt, Osmerus mordax (Mitchill), is an osmerid fish that exhibits extensive life-history diversity throughout watersheds of northeastern North America. There are both ???sea-run (anadromous) and lake-resident (lacustrine) populations and the latter have diversified further into “dwarf-” and “normal-sized” life-history types. Anadromous and lacustrine smelt may inhabit the same watershed and there are several instances where dwarf and normal populations reside within the same lake. We assayed variation among smelt for morphological traits linked to feeding performance in fishes to see if trophic ecology might promote life-history diversity in Osmerus. We also examined mitochondrial DNA (mtDNA) restriction site variation among forms to assess their evolutionary interrelationships. Dwarf smelt had significantly more gill rakers, larger eyes, but shorter upper jaws than normal lake and anadromous smelt. The populations clustered into two trophic “morphotypes”; an anadromous/normal lake group of populations and a group consisting only of dwarf smelt. The mtDNAs of 444 smelt from 16 populations were digested with 12 restriction enzymes revealing 93 composite mtDNA genotypes that clustered (UPGMA) into two major phylogenetic groups differing by 0.78% in sequence. Both genetic groups were present in dwarf and normal smelt as well as in anadromous fish. Further, geographic proximity, rather than trophic morphotype, appeared to be the major determinant of genetic affinities among populations. In two lakes, however, dwarf and normal smelt populations had significantly different mtDNA genotype frequency distributions indicating that the forms are reproductively isolated within both lakes. A clustering analysis of population affinities suggested that the divergence of sympatric dwarf and normal populations had occurred independently in the two lakes. We concluded (1) that trophic ecology is an important factor promoting differentiation in smelt life histories; (2) that smelt ecotypes are polyphyletic and there have been multiple, independent divergences of Osmerus life-history types throughout northeastern North America; and (3) that the biological and mtDNA differences between coexisting dwarf and normal lake smelt argue strongly that their genetic isolation may have developed sympatrically.  相似文献   

3.
To fully understand how plastic is affecting the ocean, we need to understand how marine life interacts directly with it. Besides their ecological relevance, microbes can affect the distribution, degradation and transfer of plastics to the rest of the marine food web. From amplicon sequencing and scanning electron microscopy, we know that a diverse array of microorganisms rapidly associate with plastic marine debris in the form of biofouling and biofilms, also known as the “Plastisphere.” However, observation of multiple microbial interactions in situ, at small spatial scales in the Plastisphere, has been a challenge. In this issue of Molecular Ecology Resources, Schlundt et al. apply the combination labelling and spectral imaging – fluorescence in situ hybridization to study microbial communities on plastic marine debris. The images demonstrate the colocalization of abundant bacterial groups on plastic marine debris at a relatively high taxonomic and spatial resolution while also visualizing biofouling of eukaryotes, such as diatoms and bryozoans. This modern imaging technology provides new possibilities to address questions regarding the ecology of marine microbes on plastic marine debris and describe more specific impacts of plastic pollution in the marine food webs.  相似文献   

4.
Rapid adaptation to novel environments may drive changes in genomic regions through natural selection. However, the genetic architecture underlying these adaptive changes is still poorly understood. Using population genomic approaches, we investigated the genomic architecture that underlies rapid parallel adaptation of Coilia nasus to fresh water by comparing four freshwater-resident populations with their ancestral anadromous population. Linkage disequilibrium network analysis and population genetic analyses revealed two putative large chromosome inversions on LG6 and LG22, which were enriched for outlier loci and exhibited parallel association with freshwater adaptation. Drastic frequency shifts and elevated genetic differentiation were observed for the two chromosome inversions among populations, suggesting that both inversions would undergo divergent selection between anadromous and resident ecotypes. Enrichment analysis of genes within chromosome inversions showed significant enrichment of genes involved in metabolic process, immunoregulation, growth, maturation, osmoregulation, and so forth, which probably underlay differences in morphology, physiology and behavior between the anadromous and freshwater-resident forms. The availability of beneficial standing genetic variation, large optimum shift between marine and freshwater habitats, and high efficiency of selection with large population size could lead to the observed rapid parallel adaptive genomic change. We propose that chromosomal inversions might have played an important role during the evolution of rapid parallel ecological divergence in the face of environmental heterogeneity in C. nasus. Our study provides insights into the genomic basis of rapid adaptation of complex traits in novel habitats and highlights the importance of structural genomic variants in analyses of ecological adaptation.  相似文献   

5.
Three populations of Arctic charr Salvelinus alpinus from southern Baffin Island were previously identified to display variable migratory phenotypes, with an anadromous component of the population and another remaining resident in fresh water. In this study, 14 microsatellite markers were used to help distinguish between two alternative hypotheses to explain the co‐existence of the two ecotypes: that the two ecotypes originate from a single population and are the result of a conditional mating tactic or that the migratory ecotypes are reproductively isolated populations utilizing alternative migratory strategies. In two of the three replicate systems, FST values between the resident and anadromous individuals were non‐significant, while they were significant in a third sampling location. Bayesian clustering analysis implemented in structure, however, failed to identify any within‐location clustering in all three sampling locations. It is concluded from these analyses that the life‐history ecotypes are most likely conditional mating tactics, rather than reproductively isolated populations. Other evidence in favour of the alternative mating tactic hypothesis is briefly reviewed, and implications for management of those populations are discussed.  相似文献   

6.
Li P  Yang G H 《农业工程》2007,27(7):2954-2963
The eco-footprint analysis of tourism is one of the most up-to-date and effective methods used to analyze the environmental effects of tourism. This study constructs a model to calculate the ecological footprint (EF) of tourism itinerary products by using a component approach, rudimentarily exploring the calculation methods for EF which target necklace-like tourism itinerary products and base tourist trips. By applying the model to calculate and analyze an “8-day tour of Shangri-La”, a typical tourism itinerary product, results of this study suggest that: (a) Tourism is a kind of life style with tremendous ecological consumption, that is, per capita EF that tourists produce in the course of travel is more than the one that local people produce in their daily life in tourist source areas, and it also exceeds the per capita EF that local people produce in their daily life in tourist destination; (b) According to the component approach, EF of tourism itinerary products is broken down into 7 components, among which “Transport”, “Food”, “Waste” and “Accommodation” play important roles; (c) There exist significant differences in ecological efficiency between different departments of tourism; the travel and entertainment sectors maintain a relatively high ecological efficiency, while the food and lodging departments have relatively low ecological efficiency.  相似文献   

7.
The goals of the subproject “molluscs” within the inter‐disciplinary research project “Indicator systems for the characterisation and prediction of ecological changes in floodplain systems” were: – develop further existing mollusc‐based indicator systems of site quality and to test their transferability, – characterise grassland sites within the recent floodplains of three study areas along the Elbe River, – analyse the relationships between indicator species‐/groups and abiotic parameters, – compile and use selected species traits in the analytical process. The results clearly show several characteristic species groups related to the hydrology of the sites (i.e. inundation and desiccation regime) and on to the degree of agricultural use. These dependencies can be interpreted by the simultaneous analysis of the species traits. “Models” are proposed, that are applicable to nature protection measures at the landscape scale. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

8.
Migratory behaviour patterns in animals are controlled by a complex genetic architecture. Rainbow trout (Oncorhynchus mykiss) is a salmonid fish that spawns in streams but exhibits three primary life history pathways: stream‐resident (fluvial), lake‐migrant (adfluvial) and ocean‐migrant (anadromous). Previous studies examining fluvial and anadromous Omykiss have identified several genes associated with life history divergence including the presence of an inversion complex within chromosome 5 (Omy05) that appears to maintain a suite of linked genes controlling migratory behaviour. However, adfluvial trout are migratory without being anadromous, and the genetic basis for this life history has not been investigated from evolutionary perspectives. We sampled wild, native nonanadromous rainbow trout occupying connected stream and lake habitats in a southwest Alaskan watershed to determine whether these fish exhibit genetic divergence between fluvial and adfluvial ecotypes, and whether that divergence parallels that documented in fluvial and anadromous O. mykiss. Data from restriction site‐associated DNA (RAD) sequencing revealed an association between frequencies of both the Omy05 inversion complex and other single nucleotide polymorphisms (SNPs) with habitat type (stream or lake), supporting the genetic divergence of fluvial and adfluvial individuals in sympatry. The presence of a genetic basis for migration into lakes, analogous to that documented for anadromy, indicates that the adfluvial ecotype must be recognized separately from the fluvial form of Omykiss even though neither is anadromous. These results highlight the genetic architecture underlying migration and the importance of chromosomal inversions in promoting and sustaining intraspecific diversity.  相似文献   

9.
洄游型、淡水型和陆封型刀鲚的寄生蠕虫群落结构   总被引:2,自引:0,他引:2  
由于对淡水环境的适应和江湖阻隔,部分洄游型刀鲚(Coilia nasus)分化成淡水型和陆封型,为寻找区分洄游型、淡水型和陆封型这3种生态型刀鲚的寄生虫标志,并分析其寄生蠕虫群落结构特征,本文调查了3种生态型刀鲚鳃部、胃、肠和幽门盲囊中寄生蠕虫的种类和感染情况。共发现10种寄生虫,包括鳃上3种单殖吸虫:林氏异钩铗虫(Heteromazocraes lingmueni)、细长嗜鳀虫(Helciferus tenuis)和长江中华钩铗虫(Sinomazocraes changjiangensis);胃部1种复殖吸虫:鲚套茎吸虫(Elytrophallus coiliae);肠道3种线虫:简单异尖线虫(Anisakis simplex)、对盲囊线虫(Contracaecum sp.)和胃瘤线虫(Eustrongylides sp.),以及肠和幽门盲囊的3种棘头虫:陈氏刺棘虫(Acanthosentis cheni)、鲇异吻钩棘头虫(Arhythmacanthus parasiluri)、长江傲刺棘头虫(Brentisentis yangtzensis)。林氏异钩铗虫和陈氏刺棘虫在3种生态型的刀鲚中都有较高的感染率和平均丰度;海水性寄生虫细长嗜鳀虫、鲚套茎吸虫和对盲囊线虫只感染洄游型刀鲚,可作为区分洄游型刀鲚的寄生虫标志;淡水性寄生虫长江中华钩铗虫、鲇异吻钩棘头虫和长江傲刺棘头虫只在淡水型刀鲚中发现,可作为淡水型刀鲚的寄生虫标志。洄游型刀鲚的物种丰富度和Brillouin多样性最高,分别在1.25和0.19以上,淡水型刀鲚的较低,分别为0.79~1.12和0.10~0.12,陆封型刀鲚的最低,分别在0.66和0.02以下,这主要是由于淡水型和陆封型刀鲚中海水性寄生虫大部分丢失,以及淡水性寄生虫感染率和平均丰度都较低造成的。盐度降低和中间宿主缺乏是导致淡水型和陆封型刀鲚中海水性寄生虫丢失的主要原因;而淡水性寄生虫较低的感染水平可能是由于其对新宿主的适应时间较短;地理隔离可能是陆封型刀鲚中寄生虫群落多样性最低的另一重要原因。  相似文献   

10.
海洋生态环境健康已成为制约海洋经济发展的关键因素,科学评估近岸海洋生态环境整体的健康状况对持续利用海洋资源环境十分紧要。本研究基于新构建的以海洋生态系统自身状态为内核、以人类社会经济学指标为外核的“双核”评价框架和2008—2016年的调查资料,对烟台近岸海洋环境健康状况进行综合评估。结果表明: 烟台近岸海域的内核评级以“优”、“良”为主,总体上沉积物质量最好,水体环境质量稍差,而生物群落则是决定最终评级的核心因素;外核评价方面,以海洋产业产值和海洋保护区面积计算的外核得分为0.98。烟台近海最终的“双核”评价结果为“优/良+0.98”,这表明烟台近岸海域在保持高开发利用程度的情况下,目前海域生态环境健康状况仍然良好,但部分区域已经开始恶化,需在发展海洋产业的同时予以密切关注。“双核”框架的评价结果可为海洋资源开发和环境保护的管理决策提供指导,对实现海洋资源环境的可持续利用具有重要意义。  相似文献   

11.
Ecological surrogacy – here defined as using a process or element (e.g., species, ecosystem, or abiotic factor) to represent another aspect of an ecological system – is a widely used concept, but many applications of the surrogate concept have been controversial. We argue that some of this controversy reflects differences among users with different goals, a distinction that can be crystalized by recognizing two basic types of surrogate. First, many ecologists and natural resource managers measure “indicator surrogates” to provide information about ecological systems. Second, and often overlooked, are “management surrogates” (e.g., umbrella species) that are primarily used to facilitate achieving management goals, especially broad goals such as “maintain biodiversity” or “increase ecosystem resilience.” We propose that distinguishing these two overarching roles for surrogacy may facilitate better communication about project goals. This is critical when evaluating the usefulness of different surrogates, especially where a potential surrogate might be useful in one role but not another. Our classification for ecological surrogacy applies to species, ecosystems, ecological processes, abiotic factors, and genetics, and thus can provide coherence across a broad range of uses.  相似文献   

12.
Studies of mating preferences and pre-mating reproductive isolation have often focused on females, but the potential importance of male preferences is increasingly appreciated. We investigated male behavior in the context of reproductive isolation between divergent anadromous and stream-resident populations of threespine stickleback, Gasterosteus aculeatus, using size-manipulated females of both ecotypes. Specifically, we asked if male courtship preferences are present, and if they are based on relative body size, non-size aspects of ecotype, or other traits. Because male behaviors were correlated with each other, we conducted a principal components analysis on the correlations and ran subsequent analyses on the principal components. The two male ecotypes differed in overall behavioral frequencies, with stream-resident males exhibiting consistently more vigorous and positive courtship than anadromous males, and an otherwise aggressive behavior playing a more positive role in anadromous than stream-resident courtship. We observed more vigorous courtship toward smaller females by (relatively small) stream-resident males and the reverse pattern for (relatively large) anadromous males. Thus size-assortative male courtship preferences may contribute to reproductive isolation in this system, although preferences are far from absolute. We found little indication of males responding preferentially to females of their own ecotype independent of body size.  相似文献   

13.
《Biotechnology journal》2008,3(3):422-422
Edited by Lodewijk Dekker, Nottingham, UK – Computational chemistry approaches – Cell-based assays for G-Protein-coupled Receptors – Cell-based label-free technologies Methods and Advances in Biotech – Application of proteomics in biotechnology – Mining marine biological wastes for bioactive molecules – PCR-based strategy to express endogenous protein levels in yeast – Method for tracking nanogel particles – Gene expression studies on bio-electrosprayed primary cardiac myocytes Many of these exciting articles are already available online under “Early View”! A sneak preview of other content can be found under “News”. http://www.biotechnology-journal.com  相似文献   

14.
The migratory history of Dolly Varden Salvelinus malma was investigated in 30 streams in the Shiretoko Peninsula, Hokkaido, Japan, which is in the southern part of their distribution. Captured Dolly Varden were classified into two categories by their body coloration: silvery fish were thought to be an anadromous form, and non-silvery fish a fluvial form that remains in freshwater throughout its life. Forty-seven of 1,739 Dolly Varden collected in the spring and ten of 2,126 Dolly Varden collected in the autumn were silvery fish. Twenty silvery fish and 120 non-silvery fish were examined by analysis of otolith Sr:Ca ratio. Three silvery fish from autumn and 15 non-silvery fish had migrated to salt water or brackish water. The other specimens of silvery fish were regarded as smolt or pre-smolt before seaward migration. The present study suggests that Dolly Varden in the Shiretoko Peninsula have a flexible migratory history, where some of the non-silvery fish utilize marine environments while some individuals follow an anadromous life history.  相似文献   

15.
We investigated the evolution of a large facial bone, the opercle (OP), in lake populations of the threespine stickleback that were founded by anadromous ancestors, in Cook Inlet, Alaska. Recent studies characterized OP variation among marine and lake populations and mapped a quantitative trait locus with a large influence on OP shape. Using populations from diverse environments and independent evolutionary histories, we examined divergence of OP shape from that of the anadromous ancestor. We report preliminary evidence for divergence between benthic and generalist lake ecotypes, necessitating further investigation. Furthermore, rapid divergence of OP shape has occurred in a lake population that was founded by anadromous stickleback in the 1980s, which is consistent with divergence of other phenotypic traits and with OP diversification in other lake populations. By contrast, there has been limited evolution of OP shape in a second lake population that may have experienced a genetic bottleneck early in its history and lacks genetic variation for OP divergence. Taken together, the results obtained from these two populations are consistent with studies of other stickleback phenotypic traits that implicate ancestral variation in postglacial adaptive radiation of threespine stickleback in fresh water.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 832–844.  相似文献   

16.
Life history strategies and potential marine niche use of Arctic charr Salvelinus alpinus (n = 237, 84–652 mm, total body length, LT) were determined during the ice-free season (2012) at three different watercourses in south-western Greenland. All Arctic charr were collected from freshwater habitats. Based on stable isotopes of δ34S, the Arctic charr were categorized as either marine- or freshwater-dependent feeders. The use of time-integrated trophic tracers (stable isotopes of δ13C, δ15N, δ34S) suggested that several trophic groups of Arctic charr operate alongside within each fjord system. The groups suggested were one group that specialized in the marine habitat, in addition to two freshwater resident morphs (small-sized resident and/or large-growing cannibalistic individuals). Stomach contents consisted entirely of freshwater and terrestrial prey (i.e., insects), indicating that marine-dependent feeders also fed in freshwater habitats after return from their marine migration. Growth and maturity patterns further supported variable life history strategies within each watercourse. The life history strategy patterns and marine trophic niche use were consistent across the watercourses along several hundred kilometres of coastline. This study represents the first ecological baseline for partially anadromous populations of Greenland Arctic charr.  相似文献   

17.
Parallel speciation can occur when traits determining reproductive isolation evolve independently in different populations that experience a similar range of environments. However, a common problem in studies of parallel evolution is to distinguish this hypothesis from an alternative one in which different ecotypes arose only once in allopatry and now share a sympatric scenario with substantial gene flow between them. Here we show that the combination of a phylogenetic approach with life-history data is able to disentangle both hypotheses in the case of the intertidal marine snail Littorina saxatilis on the rocky shores of Galicia in northwestern Spain. In this system, numerous phenotypic and genetic differences have evolved between two sympatric ecotypes spanning a sharp ecological gradient, and as aside effect of the former have produced partial reproductive isolation. A mitochondrial phylogeny of these populations strongly suggests that the two sympatric ecotypes have originated independently several times. Building upon earlier work demonstrating size-based assortative mating as the main contributor to reproductive isolation among ecotypes, our analysis provides strong evidence that divergent selection across a sharp ecological gradient promoted the parallel divergence of body size and shape between two sympatric ecotypes. Thus, divergent selection occurring independently in different populations has produced the marine equivalent of host races, which may represent the first step in speciation.  相似文献   

18.
Sympatric forms of ecologically distinctive killer whales (Orcinus orca) have been documented worldwide. This study focused on a new case of such sympatric occurrence of the “Crozet” type and the recently described “type D” killer whales off the Crozet Islands. The two ecotypes are morphologically and genetically distinct, but they both depredate the same local longline fishery. We used observational, photo‐identification, and fishing data, collected between 2003 and 2015, to examine differences in their patterns of depredation. Of the 828 sets where ecotype could be confirmed, type D killer whales interacted with 82 (11%) of the sets, including 9 (1%) sets that were simultaneously depredated by both ecotypes. Associations between the two types were never observed. Type D killer whales typically occurred in larger groups and both ecotypes preferentially depredated Patagonian toothfish (Dissostichus eleginoides). GLMM modeling revealed that the probability of type D depredation significantly increased throughout the study period, especially in deep waters, and photo‐identification data suggested that a subset of all individuals were habituating to depredation. This study documents the partitioning of resources between two distinct ecotypes of killer whales and provides preliminary insight into the feeding ecology of the rare type D killer whale.  相似文献   

19.
Community ecology is an inherently complicated field, confounded by the conflicting use of fundamental terms. Nearly two decades ago, Fauth et al. (1996) demonstrated that imprecise language led to the virtual synonymy of important terms and so attempted to clearly define four keywords in community ecology; “community,” “assemblage,” “guild,” and “ensemble”. We revisit Fauth et al.'s conclusion and discuss how the use of these terms has changed over time since their review. An updated analysis of term definition from a selection of popular ecological textbooks suggests that definitions have drifted away from those encountered pre‐1996, and slightly disagreed with results from a survey of 100 ecology professionals (comprising of academic professors, nonacademic PhDs, graduate and undergraduate biology students). Results suggest that confusion about these terms is still widespread in ecology. We conclude with clear suggestions for definitions of each term to be adopted hereafter to provide greater cohesion among research groups.  相似文献   

20.
Theoretical ecological models, such as succession and facilitation, were defined in terrestrial habitats, and subsequently applied to marine and freshwater habitats in intertidal and then subtidal realms. One such model is the soil seed bank, defined as all viable seeds (or fruits) found near the soil surface that facilitate community restoration/recovery. “Banks of microscopic forms” have been hypothesized in aquatic habitats and recent work from aquaculture has highlighted dormancy in algal life cycle stages. To reinvigorate the discussions about these algal banks, we discuss differences in life cycles, dispersal, and summarize research on banks of macroalgal stages in aquatic ecosystems that may be easier to explore with modern advances in molecular technology. With focus on seminal work in global kelp forest ecosystems, we present a pilot study in northern California as proof of concept that Nereocystis luetkeana and Alaria marginata stages can be detected within kelp forests in the biofilm of rocks and bedrock using targeted primers long after zoospore release. Considering the increased interest in algae as an economic resource, [blue] carbon sink, and as ecosystem engineers, the potential for “banking” macroalgal forms could be a mechanism of resilience and recovery in aquatic populations that have complex life cycles and environmental cues for reproduction. Molecular barcoding is becoming an important tool for identifying banks of macroalgal forms in marine communities. Understanding banks of macroalgal stages, especially in deforested habitats with intense disturbance and grazer pressure, will allow researchers and marine resource managers to facilitate this natural process in recovery of the aquatic system.  相似文献   

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