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1.
The distribution of the allochthonous crab Percnon gibbesi and its relationships with other benthic invertebrate species was assessed inside the marine reserve of Cabo de Palos—Islas Hormigas (Mediterranean sea, Spain) and neighbouring non-protected sites. Although a significant spatial variability was detected at finer spatial scale, there was no influence of protection measures or insularity on the abundance of P. gibbesi. The presence of small holes, encrusting algae and low slope favour the colonization success of this crustacean, and the spatial distribution of these habitat features could explain the observed pattern. The abundance of P. gibbesi was similar to that of native crab species; however, a non-significant negative relationship between the abundance of P. gibbesi and native crabs (Pachygrapsus marmoratus and Eriphia verrucosa), urchins (Arbacia lixula and Paracentrotus lividus) and a snail (Phorcus turbinatus) was observed. This work highlights the importance of monitoring alien crab population densities taking structural habitat and other potentially influential factors into account and the likely effect of this alien species on the native ones.  相似文献   

2.
Understanding the environmental factors that affect the distribution and abundance of rare and threatened species can help identify priority sites for conservation action such as habitat management. The moth Cucullia lychnitis is identified in UK legislation as a priority species for conservation. Its conspicuous larvae feed on a patchily distributed host plant Verbascum nigrum, but are entirely absent from some host plant patches within the species’ range. Environmental variability among patches was investigated to understand factors affecting (i) patch occupancy by C. lychnitis and (ii) abundance of C. lychnitis, where present. Occupancy of individual V. nigrum plants within occupied patches was also investigated. The likelihood of patch occupancy increased with patch size, and decreased with patch isolation. Abundance of C. lychnitis was negatively correlated with patch isolation and with abundance of the weevil Cionus nigritarsis, which exploits the same host plant and may be a competitor. Within occupied patches, larvae of C. lychnitis were significantly more likely to be found on taller plants with more flower spikes; such plants are typical of established rather than newly-created patches. These results may help to guide efforts to conserve C. lychnitis, highlighting the importance of habitat connectivity and indicating potential management actions to promote features positively associated with larval incidence and abundance.  相似文献   

3.
4.
Differential responses by species to modern perturbations in forest ecosystems may have undesirable impacts on plant-animal interactions. If such disruptions cause declines in a plant species without corresponding declines in a primary seed predator, the effects on the plant could be exacerbated. We examined one such interaction between Pinus albicaulis (whitebark pine), a bird-dispersed, subalpine forest species experiencing severe population declines in the northern part of its range, and Tamiasciurus hudsonicus (red squirrel), an efficient conifer seed predator, at 20 sites in two distinct ecosystems. Hypotheses about squirrel habitat preferences were tested to determine how changes in forest conditions influence habitat use and subsequent levels of predispersal cone predation. We performed habitat selection modeling and variable ranking based on Akaike’s information criterion; compared the level and variance of habitat use between two forest types (P. albicaulis dominant and mixed conifer); and modeled the relationship between P. albicaulis relative abundance and predispersal cone predation. T. hudsonicus did not demonstrate strong habitat preference for P. albicaulis, and thus, declines in the pine were not met with proportional declines in squirrel habitat use. P. albicaulis habitat variables were the least important in squirrel habitat selection. Squirrel habitat use was lower and varied more in P. albicaulis-dominant forests, and predispersal cone predation decreased linearly with increasing P. albicaulis relative abundance. In Northern Rocky Mountain sites, where P. albicaulis mortality was higher and abundance lower, squirrel predation was greater than in Central Rocky Mountain sites. In ecosystems with reduced P. albicaulis abundance, altered interactions between the squirrel and pine may lead to a lower proportion of P. albicaulis contributing to population recruitment because of reduced seed availability. Reducing the abundance of competing conifers will create suboptimal squirrel habitat, thus lowering cone predation in P. albicaulis and ensuring more seeds are available for avian dispersal.  相似文献   

5.
Macrocystis integrifolia and Lessonia trabeculata form vast kelp beds providing a three-dimensional habitat for a diverse invertebrate and fish fauna off northern Chile. Habitat modifications caused by the El Niño Southern Oscillation (ENSO) are likely to alter the inhabiting communities. The aim of this study was to reveal relationships between distinct habitat structures of a M. integrifolia kelp bed, a dense L. trabeculata kelp bed and L. trabeculata patches colonizing a barren ground, and the associated dominant macrobenthic key species. Seasonally 15 sampling units (10 m2 each) of any of the three habitats were monitored by SCUBA divers, which counted sporophytes and macroinvertebrates living between the latter. Furthermore, samples of plants were analysed in the laboratory to measure the morphological variables: total plant length, maximal holdfast diameter, stipe number, number of dichotomies per stipe, frond width and total drained wet mass. Multivariate analysis showed that the L. trabeculata kelp bed is denser, with a higher number of dichotomies per stipe, whereas sporophytes of M. integrifolia are longer with more stipes and wider fronds. Sporophytes of L. trabeculata patchily present on barren ground are shorter and have more stipes compared with those in the dense L. trabeculata kelp bed. Thus, the habitats provide different three-dimensional structures. The associated macrobenthic communities show a variable degree of overlapping; however, key faunal assemblages were distinguished for each habitat. Our study provides evidence that habitat diversity drives species diversity, the more homogeneous, monospecifically composed kelp bed habitats show comparatively low diversity, mainly caused by the dominance of the ascidian P. chilensis and T. tridentata in the M. integrifolia bed, and the mussel A. ater only present in the L. trabeculata bed. Species richness and diversity is highest in the heterogeneous habitat where L. trabeculata patches interrupt the barren ground. Our study revealed morphological differences between M. integrifolia and L. trabeculata kelp beds reflected in stipe number, plant length, dichotomies per stipe, and wet mass, which influence the composition of the associated characteristic fauna and its functional relations i.e. T. niger and T. tridentata.  相似文献   

6.
Habitat degradation is one of the greatest threats to biodiversity worldwide and the main contributor to the decline of many carnivorous plant species. For carnivorous plants in the southeastern United States, including many Pinguicula species (butterwort, Lentibulariaceae), degradation via altered fire regime has been implicated in their decline. Despite this decline, limited empirical research has been conducted examining the influence of habitat structural changes (through natural succession or human management) on reproduction and prey capture by carnivorous plants. The objectives of our study were to compare reproduction and prey capture for Pinguicula lutea (yellow butterwort) in habitats with different vegetation structures in the Florida Panhandle, where differences were largely due to management history. Pinguicula lutea is a self-compatible carnivorous plant that inhabits fire-dependent longleaf pine savannas of the southeastern United States and is threatened in the state of Florida. In 2014 and 2015, 13 sites were identified occupying three different habitat structures: maintained (intermittently mowed), grassy (dominated by Aristida stricta var. beyrichiana), and woody (encroachment by Hypericum and Ilex). Reproductive output was determined by assessing fruit set and ovule fertilization rate at each site. Additionally, prey availability and prey capture were assessed at each habitat site. In general, there were no differences in either measure of reproduction across habitat structure types. There were differences in prey abundance of Collembola, Diptera, and total arthropods both in terms of availability and capture. Total arthropod availability and prey capture were lowest in grassy sites compared to maintained habitat sites and woody habitat sites. Microclimatic conditions associated with each habitat structure and leaf morphology or physiology could explain the observed arthropod abundance and prey capture patterns. This study is the first ecological assessment of plant–insect interactions for Pinguicula species of the southeastern US and highlights the importance of habitat quality and management for this understudied group of carnivorous plants.  相似文献   

7.
Out of more than 380 species of damselfish, only three lack a pelagic larval phase, Acanthochromis polyacanthus, that ranges from the Philippines to the Great Barrier Reef, and two species in the genus Altrichthys, A. azurelineatus and A. curatus, that are restricted to the Calamian Archipelago (Palawan province) in the Philippines. Therefore in a very restricted geographic area, northern Palawan, Philippines, all three species co-occur. The goal of this study was to fill a knowledge gap about the ecology of Altrichthys, where very little is currently known. Using census and behavioral approaches at 14 sites on six islands, we were able to identify adult densities, nest densities, nesting habitat preference, and brood behavior and abundance. We found that densities were very high (more than 17 individuals/100 m2 for one species) and A. azurelineatus may be displacing A. curatus at deeper depths where habitat seems of higher quality. Only one out of 14 surveyed sites contained only one species, Altrichthys curatus. Different habitat use and feeding behavior suggest that niche partitioning may play an important role in the life history of these sympatric species.  相似文献   

8.
A geographical survey of two Mnais damselfly species in the Kinki area of Japan showed evidence for character displacements when the two species were found in sympatry. Mnais costalis, a species that has polymorphic male mating types of orange-winged territorial and clear-winged non-territorial morphs (hereafter abbreviated to orange and clear morphs respectively) in allopatry often shifted to having monomorphic orange morphs in sympatry. The mean body size of orange morphs was consistently larger than that of clear morph in allopatry. The mean body size of the sympatric orange morphs was even larger than that of allopatric orange morphs. By contrast, Mnais pruinosa, a species that also has two morphs of large orange and small clear morphs in allopatry, shifted to having monomorphic clear morphs in sympatry. The mean body size of the sympatric clear morphs was smaller than that of allopatric clear morphs. Divergence was also detected in the preference for habitat insolation conditions between sympatric Mnais damselflies. Both species in allopatric regions prefer half-light forest habitats, while in sympatric regions they showed diversified habitat preference: M. costalis preferred sunny habitats while M. pruinosa preferred shady habitats. Multiple character displacements in signal traits and habitat preference emerged in heterogeneous forest light environments are likely to have synergistic effects on the reproductive isolation of the two species.  相似文献   

9.
The round goby Neogobius melanostomus has recently invaded several major freshwater systems in Europe and North America. Despite numerous studies predicting an impact on native fish assemblages, few have attempted to demonstrate it. In this case study, we monitored the effect of N. melanostomus colonisation on abundance and habitat utilisation of both young-of-the-year (YOY) native fish and YOY western tubenose goby Proterorhinus semilunaris in a typical, medium-sized European river. Colonisation by N. melanostomus had no apparent effect on either native fish abundance and species richness or P. semilunaris abundance. Moreover, after colonisation, both native fish and P. semilunaris occupied similar niches (i.e. microhabitats) to those occupied before colonisation. While niche use of YOY N. melanostomus and P. semilunaris overlapped significantly, YOY native fish utilised different habitats from the gobiids. We suggest that N. melanostomus did not compete for resources with YOY fish in our study area due to lack of niche overlap and/or surplus resources. As N. melanostomus rapidly dominated the fish assemblage at our site, we further suggest that utilisation of an empty niche, rather than competitive superiority, was the main factor facilitating its success.  相似文献   

10.
Summer ichthyoplankton surveys were conducted in the northern Gulf of Mexico from 2007 to 2010 to characterize the distribution and abundance of tuna larvae. Larval assemblages of tunas were comprised of four genera: Thunnus, Auxis, Euthynnus, and Katsuwonus. Thunnus were the most abundant and four species were detected; T. atlanticus [blackfin tuna], T. obesus [bigeye tuna], T. albacares [yellowfin tuna], and T. thynnus [bluefin tuna]. Intra- and inter-annual variability in the distribution and abundance of Thunnus species were observed with higher densities in 2008 and 2009, with a decline in abundance observed in 2010. Distribution and abundance of Thunnus larvae were influenced by physical and chemical conditions of the water mass, notably sea surface temperature and salinity. Distinct species-specific habitat preferences were observed and the location of mesoscale oceanographic features influenced larval abundance with higher densities of T. atlanticus, T. obesus, and T. albacares near anticyclonic (warm core) regions and the Loop Current, while T. thynnus was observed in higher densities near cyclonic (cold core) regions. This study demonstrates that spatial and temporal variability in the location of mesoscale oceanographic features may be important to partitioning nursery habitat among Thunnus species.  相似文献   

11.
Environmental sampling yielded two yeast species belonging to Microstromatales (Exobasidiomycetes, Ustilaginomycotina). The first species was collected from a leaf phylloplane infected by the rust fungus Coleosporium plumeriae, and represents a new species in the genus Jaminaea, for which the name Jaminaea rosea sp. nov. is proposed. The second species was isolated from air on 50% glucose media and is most similar to Microstroma phylloplanum. However, our phylogenetic analyses reveal that species currently placed in Microstroma are not monophyletic, and M. phylloplanum, M. juglandis and M. albiziae are not related to the type species of this genus, M. album. Thus, Pseudomicrostroma gen. nov. is proposed to accommodate the following species: P. glucosiphilum sp. nov., P. phylloplanum comb. nov. and P. juglandis comb. nov. We also propose Parajaminaea gen. nov. to accommodate P. albizii comb. nov. and P. phylloscopi sp. nov. based on phylogenetic analyses that show these are not congeneric with Jaminaea or Microstroma. In addition, we validate the genus Jaminaea, its respective species and two species of Sympodiomycopsis and provide a new combination, Microstroma bacarum comb. nov., for the anamorphic yeast Rhodotorula bacarum. Our results illustrate non-monophyly of Quambalariaceae and Microstromataceae as currently circumscribed. Taxonomy of Microstroma and the Microstromataceae is reviewed and discussed. Finally, analyses of all available small subunit rDNA sequences for Jaminaea species show that J. angkorensis is the only known species that possess a group I intron in this locus, once considered a potential feature indicating the basal placement of this genus in Microstromatales.  相似文献   

12.
Length-weight and length-length relationships are presented for two fish species collected during May 2015 to August 2016 from Narora site of the river Ganga. The parameters a and b of the length-weight relationships were estimated after the logarithmic transformation of the equation: W = aL b . The lengthlength relationships were also estimated using linear regressions. The coefficients of determination (R 2) values were >0.9 for both target fish species and linear regressions were highly significant (p < 0.001). Length-weight relationship indicated positive allometric growth pattern for Cirrhinus mrigala and negative allometric growth pattern for Xenentodon cancila. Length-length relationships for the selected fish species were also highly significant (R 2 > 0.9, p < 0.001).  相似文献   

13.
Syngnathus abaster is an euryhaline species, which has penetrated freshwaters in Europe and its range is expanding. The goal was to investigate the feeding patterns of this species in an invaded freshwater habitat, where it first appeared at the beginning of 1990s, with implications for assessing its possible effects on invaded ecosystems. In total, 36 prey items were identified in the diet of S. abaster. The most important prey were zooplanktonic organisms, among which copepods predominated significantly. The second most important prey were cladocerans, represented by 20 species/genera. The diet composition of this species showed clear seasonal dynamics but copepods remained the predominant prey item throughout the year. Significant positive relationships between the abundance of zooplanktonic organisms in the gut contents of S. abaster and their abundance in zooplankton samples were found for copepods and Ceriodaphnia sp. S. abaster showed a significant positive electivity for copepods throughout all months. It also positively selected some large cladocerans, which probably shared the same habitat. S. abaster also consumed fish items including gobiid larvae and its own juveniles, when they were abundant in May and especially in June. The possible effect of S. abaster on native ecosystems may include the shaping of zooplanktonic communities through selective predation on copepods. This species is unlikely to be a serious food competitor for native fish inhabiting European freshwaters, the majority of which are cyprinids. Nevertheless, it can have effects on some native fish through predation on their juveniles, which might share the same habitats.  相似文献   

14.
Two new species of Metarhizium, M. bibionidarum and M. purpureogenum are described from Japan. Metarhizium bibionidarum is the phylogenetic sister species of M. pemphigi and a member of the M. flavoviride species complex. It is distinguished morphologically from M. pemphigi by its larger conidia. The species is based on a collection of an infected March fly larva (Diptera: Bibionidae) but is also known to occur on fruit beetle (Coleoptera: Scarabaeidae) encountered in France. Metarhizium purpureogenum was isolated from soil by plating and insect baiting methods and represents a unique phylogenetic lineage placed outside the M. anisopliae and M. flavoviride species complexes. Three isolates of M. purpureogenum excreted a distinctive red-purple pigment into agar medium when co-cultured with M. robertsii or Aspergillus oryzae.  相似文献   

15.
Four new species of Mariannaea were described in this paper, namely M. chlamydospora, M. cinerea, M. fusiformis, and M. lignicola. Mariannaea chlamydospora is characterized by its cream-colored, zonate colonies on PDA, smooth conidiophores, fusiform conidia, and abundant chlamydospores. Mariannaea cinerea forms grey colonies and ellipsoidal to subglobose conidia. Mariannaea fusiformis forms purple colonies and fusiform to subglobose conidia. Mariannaea lignicola has brown conidiophores and broad hyphae. The molecular phylogeny was inferred using ITS, LSU, and TUB-2 loci. The type species of Mariannaea (M. elegans) is epitypified. The variety M. elegans var. punicea is raised to species rank. Mariannaea clavispora is excluded from Mariannaea because of its cylindrical phialides, straight conidial chains and deviating phylogenetic affinity. Mariannaea nipponica did not fit well the generic concept of Mariannaea based on their morphological characters, and its generic placement remains uncertain. A key to the currently accepted 15 species of Mariannaea is provided.  相似文献   

16.
During a parasitological survey of the ichthyofauna of Lake Catemaco, a freshwater system in the Mexican State of Veracruz, the widespread copepod Ergasilus arthrosis Roberts, 1969 was recovered from two cichlid teleosts, Mayaheros urophthalmus (Günther) and Oreochromis sp. This is the first confirmed record of this copepod species outside of the United States and from Mexico; its finding as a parasite of cichlids represents an expansion of the known host range for this copepod. The local prevalence and intensity of infection of E. arthrosis was highest in M. urophthalmus. The infection prevalence of E. arthrosis on M. urophthalmus (60%) was higher than that known for other ergasilids on cichlids. Ergasilus arthrosis can be distinguished from its closest congener E. lizae Krøyer, 1863 by the morphometry of the antennary segments, the ventral ornamentation of the thoracic sclerites and by details of the antennulary setation, but also by its habitat and host preferences. Taxonomic illustrations and morphological details of the specimens examined are also provided together with comments on the variability of this species.  相似文献   

17.
To understand the role of native ladybird biodiversity in habitat susceptibility on the establishment and spread of Harmonia axyridis Pallas (Coleoptera: Coccinellidae), we characterized and compared European communities where they had established and where they had not established. The local communities of ladybirds were characterized in terms of biodiversity, the average difference in body mass between H. axyridis and other coccinellid species and the rarefied total body mass of all individuals (as a surrogate for aphid abundance and availability). The lack of success of H. axyridis in the Azores, as well as its low success in Southern Europe, can be explained by a combination of resource availability and intraguild competition. We suggest the success of this invasive alien species to establish in a habitat depends first on resource availability and second when most direct competitors for limited resources are absent or are uncommon.  相似文献   

18.
Habitat loss and landscape degradation affect animal-mediated seed dispersal, often collapsing the regeneration of endangered plant species and habitats in anthropogenic landscapes. We first compared the role of red fox and other vertebrates as seed disperser for the keystone scrub Ziziphus lotus. Because it turned out that foxes are the major Z. lotus dispersers, we investigated how fox activity and dispersal service relate to habitat loss and landscape alteration in the threatened Ziziphus semiarid scrublands, a priority habitat for conservation in Europe. Considering its opportunistic behavior, we hypothesized that landscape features should affect moderately fox abundance, while influence in a large extent its dispersal service. Accordingly, we predicted that a substantial decline in Ziziphus fruit consumption rather than in disperser activity would be responsible for seed dispersal collapse under severe habitat loss. We evaluated fox activity and dispersal service in 17 populations of Z. lotus spread through the range of its habitat in Spain and found within landscapes with different land-use intensity. We certified the collapse of the dispersal service by fox under severe habitat loss and confirmed that fox activity was less affected by habitat loss or landscape alteration than consumption of Ziziphus fruits. Consequently, the decline of consumption of Ziziphus fruits under severe habitat loss triggers the collapse of its seed dispersal. Results suggest that without increase of the remnant areas other managements may not suffice to achieve seed dispersal and habitat restoring. Dispersal service and natural regeneration in many Ziziphus habitat remnants will possibly cease in the future if habitat loss continues.  相似文献   

19.
Primate vocalizations convey a variety of information to conspecifics. The acoustic traits of these vocalizations are an effective vocal fingerprint to discriminate between sibling species for taxonomic diagnosis. However, the vocal behavior of nocturnal primates has been poorly studied and there are few studies of their vocal repertoires. We compiled a vocal repertoire for the Endangered Sambirano mouse lemur, Microcebus sambiranensis, an unstudied nocturnal primate of northwestern Madagascar, and compared the acoustic properties of one of their call types to those of M. murinus and M. rufus. We recorded vocalizations from radio-collared individuals using handheld recorders over 3 months. We also conducted an acoustic survey to measure the vocal activity of M. sambiranensis in four forest habitat types at the study site. We identified and classified five vocalization types in M. sambiranensis. The vocal repertoires of the three Microcebus species contain very similar call types but have different acoustic properties, with one loud call type, the whistle, having significantly different acoustic properties between species. Our acoustic survey detected more calls of M. sambiranensis in secondary forest, riparian forest, and forest edge habitats, suggesting that individuals may prefer these habitat types over primary forest. Our results suggest interspecific differences in the vocal repertoire of mouse lemurs, and that these differences can be used to investigate habitat preference via acoustic surveys.  相似文献   

20.

Background

Aspergillus fumigatus is the species section Fumigati most frequently isolated from the respiratory tract of cystic fibrosis (CF) patients. Recent studies suggest that mutations in the Cyp51 gene, particularly TR34/L98H, are responsible for azole resistance.

Objectives and Methods

The focus of this study was on section Fumigati isolates isolated from the respiratory tract samples of CF patients. More specifically, the goal was to detect A. fumigatus isolates, test their antifungal susceptibility to itraconazole, voriconazole and posaconazole, and finally determine the presence of TR34/L98H and other mutations in the isolates Cyp51A gene.

Results and Conclusions

A set of 31 isolates of Aspergillus section Fumigati were obtained from the sputum samples of 6 CF patients and subsequently identified to species level by microsatellite genotyping. All isolates were determined as A. fumigatus and involved 14 different genotypes. The minimal inhibitory concentrations to the three azoles were determined by the E-test method, and the Cyp51A gene was sequenced. One of the genotypes was found to be resistant to all azoles but no mutations were detected in the Cyp51A gene, especially the TR34/L98H mutation. Therefore, mutations in genes other than Cyp51A or other distinct mechanisms may be responsible for this reported multiazole resistance found in a Turkish CF patient.
  相似文献   

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