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1.
The Mucor genus, a polyphyletic group pertaining to early diverging lineages of fungi, includes a high number of ubiquitous species. Some species have positive or negative impacts on human activities. Indeed, certain pathogenic Mucor species are a threat for animal and human health and identified more frequently as mycosis causative agents, especially in immunocompromised patients. On the contrary, a small number of Mucor species have been used for centuries in food manufacturing for cheese ripening or Asian fermented food production. Some species are also used as biotechnologically important microorganisms due to their high growth rates, dimorphism (for certain species) and their previously unsuspected potential for secondary metabolite production. Despite all these important roles played by Mucor spp., they have been less investigated than ascomycetous or basidiomycetous species and their taxonomy, metabolism and ecology are less documented when compared to their counterparts in the so-called higher fungi. Nevertheless, research focusing most often on the emblematic Mucor circinelloides species has led to increased knowledge on the biology of this genus, and overall on fungal biology. This is particularly documented for fungal dimorphism or light-induced gene regulation. The aim of this review is to give an overview of the current knowledge on Mucor morphology, taxonomy, ecology and genetics and of its importance regarding human health and industrial applications.  相似文献   

2.
Understanding the evolution of sexually dimorphic traits requires knowledge of the genetic and environmental sources of variation. However, we know surprisingly little about how the sexes differ in their responses to environmental nutrient supply. Here, we investigated how phosphorus (P) availability, a key metric of eutrophication, affects body composition in each sex of two Hyalella amphipod species. We also examined whether differences in food preference and acquisition are responsible for observed variation in body P. We discovered environmentally-driven changes in body P that were dependent on both species and sex. In both species, males contained less P when raised in low-P laboratory conditions compared to high-P field environments, while females exhibited no significant differences. Importantly, this difference was greater in the species that is known to have larger sexual traits and higher growth rates. Variation in P content was not due to differences in acquisition of P because both sexes preferred high-P food and consumed it at a similar rate. Our study illuminates potentially important sex- and species-specific evolutionary consequences of rapid alterations to P availability due to cultural eutrophication.  相似文献   

3.
Besides research on the model fungal genera Saccharomyces, Neurospora and Aspergillus, that has provided important biological knowledge in the areas of genetics, cell biology and physiology, recent investigations on non-model fungi used for food production offer insight into the mechanisms involved in food production but also adaptation and domestication processes. In this context, Penicillium roqueforti has been the most extensively studied species. This species is best known worldwide for its technological use for blue-veined cheese production and ripening. Recently, several advances related to taxonomy, population genetics, physiology and metabolism have been documented and provided deeper knowledge about this species. The methodological approaches used to study this species can be applied to other still largely understudied fungi associated with food production worldwide (e.g. P. camemberti, P. nalgiovense, P. salamii, Bisifusarium domesticum, Mucor spp.).  相似文献   

4.
The separation ofSclerotinia sclerotiorum (Lib.) de Bary, 5.trifoliorum Erikss., andS. minor Jagger into three distinct species has been based on traditional morphological and physiological criteria such as gross cultural characteristics, sclerotial size, ascus and ascospore dimensions, time of apothecial development in the field, and host association. However, these characteristics tend to be variable and some workers have concluded that the three fungi should be included in one species, 5.sclerotiorum. Recently, new data have been published on morphological, cultural, physiological, ontogenetic, enzyme pattern, mycelial interaction, and cytological characteristics of isolates ofSclerotinia spp. This information supplements, but does not replace, that available from more traditional taxonomic methods and helps to resolve the controversy on the taxonomy and nomenclature of these fungi. This article reviews the relevant literature on the biology of 5.sclerotiorum, S. trifoliorum, and 5.minor, with particular emphasis given to those differences between them that could be of significance regarding their specific nomenclature. After an introduction, mycelia, microconidia, sclerotia, apothecia, infection, control, and taxonomy and nomenclature are discussed. The authors conclude thatS. sclerotiorum, S. trifoliorum, andS. minor are distinct species. The characteristics used to distinguish between them are summarized in table form.  相似文献   

5.
《Fungal Biology Reviews》2020,34(3):126-135
Fungi are one of the main agents responsible for the biodeterioration of cultural heritage through physical and chemical processes. The frequent isolation of certain fungal species from deteriorated materials indicates that these species appear to have a particular affinity for environmental conditions occurring in cultural heritage. It is important to identify the conditions that favour the development of such species in order to understand how to preserve monuments and collections. Among these fungal species, the involvement of Parengyodontium album (Limber) Tsang et al. seems to have been underestimated until now. This species is abundant in many environments and its taxonomic position has changed quite frequently, which may have concealed the effect of this fungus on cultural heritage sites. This review seeks to compile the involvement of P. album in cultural heritage biodeterioration phenomena under all the names that it has been attributed in order to effectively determine its occurrence. This paper also aims to determine whether P. album is marginal or dominant when detected on materials. Finally, the conditions that favour the development of P. album on cultural heritage objects and sites are discussed.  相似文献   

6.
Forage selection decisions of herbivores are often complex and dynamic; they are modulated by multiple cues, such as quality, accessibility and abundance of forage plants. To advance the understanding of plant–herbivore interactions, we explored foraging behavior of the alpine lagomorph Royle's pika (Ochotona roylei) in Kedarnath Wildlife Sanctuary, India. Pika bite counts on food plants were recorded through focal sampling in three permanently marked plots. Food plant abundance was recorded by traditional quadrat procedures; forage selection was estimated with Jacob's selection index. Multiple food-choice experiments were conducted to determine whether forage selection criteria would change with variation in food plant composition. We also analyzed leaf morphology and nutrient content in both major food plants and abundantly available non-food plants. Linear regression models were used to test competing hypotheses in order to identify factors governing forage selection. Royle's pika fed primarily on 17 plant species and each forage selection decision was positively modulated by leaf area and negatively modulated by contents of avoided substances (neutral detergent fiber, acid detergent fiber, acid detergent lignin and tannin) in food plants. Furthermore, significance of the interaction term “leaf size × avoided substance” indicates that plants with large leaves were selected only when they had low avoided substance content. The forage selection criteria did not differ between field and laboratory experiments. The parameter estimates of best fit models indicate that the influence of leaf size or amount of avoided substance on pika forage selection was modulated by the magnitude of predation risk.  相似文献   

7.
Some of the most compelling examples of ecological responses to climate change are elevational range shifts of individual species, which have been observed throughout the world. A growing body of evidence, however, suggests substantial mediation of simple range shifts due to climate change by other limiting factors. Understanding limiting factors for a species within different contexts, therefore, is critical for predicting responses to climate change. The American pika (Ochotona princeps) is an ideal species for investigating distributions in relation to climate because of their unusual and well-understood natural history as well as observed shifts to higher elevation in parts of their range. We tested three hypotheses for the climatic or habitat characteristics that may limit pika presence and abundance: summer heat, winter snowpack, and forage availability. We performed these tests using an index of pika abundance gathered in a region where environmental influences on pika distribution have not been well-characterized. We estimated relative pika abundance via scat surveys and quantified climatic and habitat characteristics across two North-Central Rocky Mountain Ranges, the Wind River and Bighorn ranges in Wyoming, USA. Pika scat density was highest at mid-elevations and increased linearly with forage availability in both ranges. Scat density also increased with temperatures conducive to forage plant growth, and showed a unimodal relationship with the number of days below -5°C, which is modulated by insulating snowpack. Our results provide support for both the forage availability and winter snowpack hypotheses. Especially in montane systems, considering the context-dependent nature of climate effects across regions and elevations as well as interactions between climatic and other critical habitat characteristics, will be essential for predicting future species distributions.  相似文献   

8.
Peru is the top exporter of fishmeal and fish oil (FMFO) worldwide and is responsible for half and a third of global production, respectively. Landings of “anchoveta” (Engraulis ringens) are used nearly exclusively for FMFO production, despite a proactive national food policy aimed at favoring the direct human consumption of this inexpensive species. It may be surprising that in a country where malnutrition and caloric deficit constitute major issues, a low-priced and highly nutritious fish such as anchovy does not have stronger domestic demand as a food fish. Here, we review and assess eight potential politico-socio-economic processes that can explain this situation. The main explanation are dietary habits, the preference for broiler and the higher profit from anchovy sold as feed fish compared to its use as a food fish due to historically high FMFO prices, boosted by an increasing demand for aquaculture in a context of finite forage and trash fish resources. In addition, the recent introduction of an individual quota system has shifted bargaining power from processors to fishers, thereby increasing competition for the raw material. This competition results in an increase in anchovy prices offered by the feed fish industry due to its onshore processing overcapacity, which is detrimental to the food fish industry. In the end, although the dominant use of anchovy for fish feed is largely explained by integrating these market mechanisms and other minor ones, this use raises other issues, such as rent redistribution through public policies, employment, equitability and utility (low social costs), and resource management (threats to ecosystems or global change). Different policy scenarios are proposed in relation to these issues.  相似文献   

9.
The number of valid species in the genus Echinometra (Echinodermata, Echinoidea) and their associated identification keys have been debated in the scientific literature for more than 180 years. As the phylogeny and dispersal patterns of these species have been widely used as a prominent model for marine speciation, new insights into their taxonomy have the potential to deepen our understanding of marine speciation processes. In this study we examine Echinometra taxonomy, combining morphology and molecular tools. We present the taxonomy and phylogeny of Red Sea and Western Indian Ocean Echinometra. The currently available morphological keys were found to be limited in their ability to delineate all species within this genus. Nonetheless, morphological similarities between the Red Sea and Western Indian Ocean populations were high, and delimited them from the other species. These latter populations together formed a monophyletic clade, genetically distant from any of the other Echinometra species by more than 3%. Combining both traditional taxonomy and molecular evidence, we found that these populations were neither Echinometra mathaei nor E. oblonga, as previously considered. The morphological discrepancies of these populations, and their genetic divergence from the other Echinometra species, suggest that they should be considered as a new Echinometra species.  相似文献   

10.
The sacoglossan sea slug, Plakobranchus ocellatus, is a so-called long-term retention form that incorporates chloroplasts for several months and thus is able to starve while maintaining photosynthetic activity. Little is known regarding the taxonomy and food sources of this sacoglossan, but it is suggested that P. ocellatus is a species complex and feeds on a broad variety of Ulvophyceae. In particular, we analysed specimens from the Philippines and starved them under various light conditions (high light, low light and darkness) and identified the species of algal food sources depending on starvation time and light treatment by means of DNA-barcoding using for the first time the combination of two algal chloroplast markers, rbcL and tufA. Comparison of available CO1 and 16S sequences of specimens from various localities indicate a species complex with likely four distinct clades, but food analyses do not indicate an ecological separation of the investigated clades into differing foraging strategies. The combined results from both algal markers suggest that, in general, P. ocellatus has a broad food spectrum, including members of the genera Halimeda, Caulerpa, Udotea, Acetabularia and further unidentified algae, with an emphasis on H. macroloba. Independent of the duration of starvation and light exposure, this algal species and a further unidentified Halimeda species seem to be the main food source of P. ocellatus from the Philippines. It is shown here that at least two (or possibly three) barcode markers are required to cover the entire food spectrum in future analyses of Sacoglossa.  相似文献   

11.
In Zaire the distribution of four of the wild species in the genusPsophocarpus ranges from humid, evergreen, Guinea-Congolian rainforests to high altitude woodlands, dry semi-deciduous forests, and savanna. Material ofPsophocarpus scandens, P. grandiflorus, P. lancifolius, P. lecomtei, andP. lancifolius (yellow-seeded form) were collected from wild and naturalized populations in Zaire. Various organs ofP. scandens, P. grandiflorus, andP. lancifolius are used as food sources, medicinals, and as sources of tannins.Psophocarpus lancifolius andP. lecomtei have reportedly been used as a food source and fish poison, respectively. The various organs were analyzed for carbohydrate, lipid, N, S, P, K, Mg, Ca, Na, Fe, Al, Mn, B, Cu, and Zn. In their own right, these species have potential for wider use as food sources and genetic material for improvement breeding with the cultivated winged bean, Local names, phenological notes, presence of pests and diseases, and ecogeographical information are presented.  相似文献   

12.
Day geckos of the Phelsuma lineata group are widespread in Madagascar and have been historically split into numerous species and subspecies based almost exclusively on differences in coloration and body size. We apply phylogenetic and phylogeographic methods to examine the biogeography and taxonomy of these lizards, including explicit tests of various biogeographic predictions and based on a molecular data set covering much of the distribution ranges of all species and subspecies of P. lineata, P. dorsivittata, P. comorensis, P. hoeschi, P. kely, and P. pusilla in Madagascar (and the Comoros archipelago for P. comorensis). Sequences of the mitochondrial 16S rRNA and the nuclear RAG-1 gene fragment were determined from 376 samples, and a multigene mtDNA phylogeny of the species group was constructed for the main phylogroups identified in the 16S haplotype network. We used the 16S sequences to estimate the geographic location of the ancestor of each major mtDNA clade and to infer their demographic history using a variety of statistical tools. Our phylogeny separates the taxa analyzed into two well-supported major subclades mainly occurring in the north respectively east of the island. Mismatch distribution of samples together with rejection of neutrality, the results of Bayesian Skyline Plots analysis, and a star-like network suggests a recent demographic expansion for the P. l. lineata lineage into the eastern lowlands, while the highland (P. l. elanthana) and northern clades (P. dorsivittata and P. l. punctulata) show signatures of rather stable populations. A major genetic discontinuity observed coincided with a northern lowland stretch that separates mid-altitude rainforests in the north from those in the center and south. Our analysis points to numerous unsolved taxonomic problems in this group of geckos, especially in the small-sized taxa (P. hoeschi, P. kely, P. pusilla), and provides a basis for a future comprehensive taxonomic revision, which will require integrative analysis of molecular, morphological and chromatic data as well as careful examination of type specimens.  相似文献   

13.
Information about the biology of spittlebugs on different species of forage is necessary for the development of tactics for their control, and is also essential for evaluating, selecting and launching new forage cultivars. The aims of this study were to compare the nutritional suitability of different forage species–Brachiaria ruziziensis (Congo grass), Pennisetum purpureum (elephant grass), Panicum maximum (Guinea grass), and Cynodon dactylon (Bermuda grass)–for the spittlebug species Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae), Deois schach (Fabricius) (Hemiptera: Cercopidae) and Notozulia entreriana (Berg) (Hemiptera: Cercopidae), and to evaluate the performance of each spittlebug species on forage monocultures. B. ruziziensis was the most suitable host plant for D. schach. Since N. entreriana did not show differences in the evaluated parameters, it was not possible to determine its ideal forage species. For M. spectabilis, P. purpureum was the most suitable forage species. The evaluation of the performance of the different spittlebugs on a single forage species also showed which spittlebugs are a problem. M. spectabilis and D. schach developed better on a monoculture of B. ruziziensis. M. spectabilis was a major problem when it fed on P. purpureum, but on C. dactylon and P. maximum, none of the spittlebugs developed properly, indicating that these plants are less suitable for them. These results suggest that the forage diversification of pastures may be a strategy for the integrated management of spittlebugs.  相似文献   

14.
The process of ecological speciation drives the evolution of locally adapted and reproductively isolated populations in response to divergent natural selection. In Southern Mexico, several lineages of the freshwater fish species of the genus Poecilia have independently colonized toxic, hydrogen sulfide-rich springs. Even though ecological speciation processes are increasingly well understood in this system, aligning the taxonomy of these fish with evolutionary processes has lagged behind. While some sulfide spring populations are classified as ecotypes of Poecilia mexicana, others, like P. sulphuraria, have been described as highly endemic species. Our study particularly focused on elucidating the taxonomy of the long described sulfide spring endemic, Poecilia thermalis Steindachner 1863, and investigates if similar evolutionary patterns of phenotypic trait divergence and reproductive isolation are present as observed in other sulfidic species of Poecilia. We applied a geometric morphometric approach to assess body shape similarity to other sulfidic and non-sulfidic fish of the genus Poecilia. We also conducted phylogenetic and population genetic analyses to establish the phylogenetic relationships of P. thermalis and used a population genetic approach to determine levels of gene flow among Poecilia from sulfidic and non-sulfidic sites. Our results indicate that P. thermalis'' body shape has evolved in convergence with other sulfide spring populations in the genus. Phylogenetic analyses placed P. thermalis as most closely related to one population of P. sulphuraria, and population genetic analyses demonstrated that P. thermalis is genetically isolated from both P. mexicana ecotypes and P. sulphuraria. Based on these findings, we make taxonomic recommendations for P. thermalis. Overall, our study verifies the role of hydrogen sulfide as a main factor shaping convergent, phenotypic evolution and the emergence of reproductive isolation between Poecilia populations residing in adjacent sulfidic and non-sulfidic environments.  相似文献   

15.
Arctostylopids are enigmatic mammals known from the Paleocene and Early Eocene of Asia and North America. Based on molar similarities, they have most often been grouped with the extinct Notoungulata from South and Central America, but tarsal evidence links them to Asian basal gliriforms. Although Palaeostylops is the best-known arctostylopid genus, some points of its content and species level taxonomy remain uncertain. Here we report 255 upper and lower jaw fragments of Palaeostylops, five calcanea, three astragali, as well as the first known arctostylopid distal tibia. This new material was collected from the late Paleocene of the Flaming Cliffs area in Mongolia, in a single lens almost exclusively containing arctostylopid remains. Our study of the morphology and size of the new Palaeostylops dental material confirms the validity of two species, P. iturus and P. macrodon, and illustrates their morphological and biometrical variability and diagnostic differences. The distal tibia of Palaeostylops is relatively unspecialised and resembles the Asian gliriforms Pseudictops and Rhombomylus. We also review the relevance of the historically important genus Palaeostylops in view of other, more recently described but less abundant arctostylopid genera. Palaeostylops remains the reference taxon for the arctostylopid anterior dentition and postcranial morphology. For both anatomical regions, arctostylopids differ significantly from notoungulates, and present a mosaic of characters also seen in basal gliriforms. The notoungulate-like molars of Palaeostylops are highly specialized for arctostylopids and the arctostylopid molar morphotype is therefore better illustrated by the early middle Paleocene Asiostylops. This morphotype does not present any similarities to notoungulates, but shares a number of derived characters with basal gliriforms. Among gliriforms, the primitive arctostylopid morphotype is most similar to Astigale from the early Paleocene of South China, and we suggest that Arctostylopidae may therefore be more closely related to Astigalidae than to any other group.  相似文献   

16.
Among pair-living species, which represent a simple form of gregariousness, the degree of cohesion appears to be highly variable, but the mechanisms responsible for the maintenance of cohesiveness have been poorly studied. We present data from long-term behavioural observations of eight pairs of fork-marked lemurs, including year-round data on their sleeping site use and spatial data from simultaneous focal follows of both pair partners, that characterize its social organization as ‘dispersed pairs’. Although pairs were stable over several years, territories of pair partners overlapped almost perfectly and interactions between them were frequent, the cohesiveness of pairs was extremely low. High rates of conflict relative to frequencies of affiliative interactions indicated that avoidance of the pair partner is the key mechanism responsible for the observed pattern of space use. The repeated use of the same predictable food resources during the night, frequent conflicts over food and patterns of vocal communication imply that avoidance of direct feeding competition, together with incomplete knowledge about the pair partner's position, lead to the observed low cohesiveness. The freedom to forage solitarily and the associated lack of information about the pair partner's position found in fork-marked lemurs are in contrast to most group-living species and qualify dispersed pairs as a focus for future studies of models on animal movement decisions. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.   相似文献   

17.
The daily food intake and feeding activities of the common gobyPomatoschistus microps (Krøyer) and the nine-spined sticklebackPungitius pungitius (L.) were investigated in the brackish Schlei fjord. At the investigation site of Olpenitz, salinities varied between 11 and 15‰, and water temperatures between 5 and 18°C during the period of in-situ experiments in 1981 and 1982. Common gobies sometimes attained a density of more than 100 individuals per square metre, nine-spined sticklebacks as much as 18 individuals per square meter. Their food changed depending on the supply of plankton or benthos. Regarding numbers, their food consisted mainly of harpacticoids, in springtimes of calanoids; with regard to weight, amphipods, polychaetes or chironomid larvae often prevailed. The total food ingestion, measured by means of its relation to fish weights (fullness index), was highest in spring and summer: 2.3% inP. microps and 2.6% inP. pungitius. Low fullness indices of 0.8% inP. microps and 0.3% inP. pungitius were found during times of low water temperatures. 24-h field investigations revealed that the adultP. microps presented clear diurnal rhythms with highest fullness indices after dawn and a further maximum at dusk. Only young gobies ingested some benthos at night.P. pungitius displayed similar rhythms in which maximum fullness indices varied during the day. This species seems to forage every four hours. At dusk, both species preferred benthos to plankton. The results are discussed with respect to the implications of diurnal and seasonal fluctuations in prey choice by small-sized fish populations.  相似文献   

18.
It was hypothesised that subtle topographical differences might cause the existence of ecotypes along a floodplain. The apomict grass Paspalum dilatatum subspecies dilatatum inhabits flood‐prone lowlands as well as nearby uplands in the floodplains of Argentina, while the sexual P. dilatatum subspecies flavescens almost exclusively inhabits the uplands. The aim of the present study was to identify the different traits that allow these P. dilatatum populations to inhabit different habitats. Plants of P. dilatatum were reciprocally transplanted between uplands and lowlands. Morphophysiological traits related to flooding tolerance were measured during a flood. Subspecies dilatatum from the uplands and subspecies flavescens showed a high physiological performance in the uplands but a considerable decrease in stomatal conductance, net photosynthesis rates and tiller number in the flooded lowlands. In contrast, the subspecies dilatatum from the lowlands showed relatively lower and stable stomatal conductance, photosynthesis rates and leaf water potential at both sites. Subspecies dilatatum from the lowlands outperformed upland populations at the lowland site with respect to tillering. Leaves of subspecies dilatatum from the lowlands that had grown at the lowland habitat had a lower blade/sheath proportion than leaves of plants transplanted to the uplands. This behavior did not occur in both upland populations. Results suggest that dilatatum Lowland plants have the typical strategy of stress‐tolerant genotypes and that the upland populations are adapted to habitats where competitive species are selected. In conclusion, habitats with subtle differences in topographic level can favour both ecotypic differentiations within an apomict subspecies but also the maintenance of morphophysiological similitudes between coexisting upland populations belonging to different subspecies.  相似文献   

19.
Closed-canopy upland hardwood stands often lack diverse understory structure and composition, limiting available nutrition for white-tailed deer (Odocoileus virginianus) as well as nesting and foraging structure for other wildlife. Various regeneration methods can positively influence understory development; however, non-commercial strategies are needed to improve available nutrition in many stands, as some contain timber that is not ready to harvest and others are owned by landowners who are not interested in harvesting timber. Applications of herbicide and prescribed fire have improved availability of food and cover for deer and other wildlife in pine (Pinus spp.) systems. However, this strategy has not been evaluated in hardwood systems. To evaluate the influence of fire and herbicide treatments on available deer forage in upland hardwood systems, we measured forage availability and calculated nutritional carrying capacity (NCC) at 14% crude protein mixed diet, following 7 silvicultural treatments, including controls, in 4 mixed upland hardwood stands July–September 2007 and 2008. We compared NCC among forest treatments and within 4 paired warm-season forage food plots to evaluate the usefulness of food plots in areas where forests are managed. Nutritional carrying capacity estimates (deer days/ha) were greatest following canopy reduction with prescribed fire treatments in both years. Understory herbicide application did not affect species composition or NCC 1 year or 2 years post-treatment. Production of forage plantings exceeded that of forest treatments both years with the exception of early-maturing soybeans and retention cut with fire 2 years post-treatment. We encourage land managers to use canopy reducing treatments and low-intensity prescribed fire to increase available nutrition and improve available cover where needed in upland hardwood systems. In areas where deer density may limit understory development, high-quality forage food plots may be used to buffer browsing while strategies to reduce deer density and stimulate the forest understory are implemented. © 2011 The Wildlife Society.  相似文献   

20.
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