The effects of patch harvesting and site preparation on ground beetles (Coleoptera, Carabidae) in yellow birch dominated forests of southeastern Quebec

2005 ◽  
Vol 35 (11) ◽  
pp. 2616-2628 ◽  
Author(s):  
Jan Klimaszewski ◽  
David W Langor ◽  
Timothy T Work ◽  
Georges Pelletier ◽  
HE James Hammond ◽  
...  
Keyword(s):  
A Priori ◽  
Similarity Measures ◽  
Ground Beetles ◽  
Site Preparation ◽  
Yellow Birch ◽  
Eastern Canada ◽  
Generalist Species ◽  
Clear Cut ◽  
Open Habitat ◽  
Specialist Species

We studied the impacts of increasing size and number of gapcuts and the effects of site preparation by scarification on the species richness and community composition of ground beetles (Coleoptera: Carabidae), using pitfall traps in early-successional yellow birch dominated forests in eastern Canada. Catches of all carabids, forest specialists, and generalists were generally higher in uncut controls than in treatments. The catch of open-habitat specialists was generally lower in controls than in treatments. Although not significant, there was a common trend for scarification to decrease the catches of forest specialists and generalists. Bray–Curtis similarity measures and nonmetric multidimensional scaling ordination indicated that the composition of the carabid assemblage was more affected by harvesting treatment than by scarification. Carabid species composition varied consistently with increasing gap size and corresponded to the a priori generalized habitat-preference designations. Forest-specialist species were confined to uncut sites, while generalist species were widely distributed across all sites. Open-habitat species were found predominantly in clear-cut and two-gap sites. Hygrophilous species were consistently associated with two-gap, four-gap, and clear-cut sites. Small-gap harvesting is more favorable to the maintenance of the structure of natural arthropod assemblages than are traditional, larger clearcuts.

scholarly journals Analysis of Residual Dependencies of Independent Components Extracted from fMRI Data

2016 ◽  
Vol 2016 ◽  
pp. 1-15
Author(s):  
N. Vanello ◽  
E. Ricciardi ◽  
L. Landini
Keyword(s):  
Clustering Algorithm ◽  
A Priori ◽  
Similarity Measures ◽  
Real Data ◽  
Fmri Data ◽  
Order Selection ◽  
Functional Magnetic Resonance ◽  
Model Order Selection ◽  
Model Order ◽  
Independent Components

Independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data can be employed as an exploratory method. The lack in the ICA model of strong a priori assumptions about the signal or about the noise leads to difficult interpretations of the results. Moreover, the statistical independence of the components is only approximated. Residual dependencies among the components can reveal informative structure in the data. A major problem is related to model order selection, that is, the number of components to be extracted. Specifically, overestimation may lead to component splitting. In this work, a method based on hierarchical clustering of ICA applied to fMRI datasets is investigated. The clustering algorithm uses a metric based on the mutual information between the ICs. To estimate the similarity measure, a histogram-based technique and one based on kernel density estimation are tested on simulated datasets. Simulations results indicate that the method could be used to cluster components related to the same task and resulting from a splitting process occurring at different model orders. Different performances of the similarity measures were found and discussed. Preliminary results on real data are reported and show that the method can group task related and transiently task related components.

scholarly journals List of Odonates from the Floresta Nacional de São Francisco de Paula (FLONA - SFP), with two new distribution records for Rio Grande do Sul, Brazil

2016 ◽  
Vol 16 (3) ◽  
Author(s):  
Samuel Renner ◽  
Eduardo Périco ◽  
Göran Sahlén
Keyword(s):  
Rio Grande ◽  
Rio Grande Do Sul ◽  
Generalist Species ◽  
Small Streams ◽  
Specialist Species ◽  
Ombrophilous Forest ◽  
First Time ◽  
Pristine Forest ◽  
New Distribution ◽  
Open Fields

Abstract A survey of Odonata was carried out in the National Forest FLONA - SFP, Northeastern region of the Rio Grande do Sul state, Brazil. This conservation unit is mainly covered by Mixed Ombrophilous Forest (MOF), a subtype of Atlantic Forest biome, being also areas covered in planted Pinus, planted Araucaria and open fields. Our sampling efforts were conducted in thirty aquatic environments inside this reserve during the period between January 2014 and November 2014. The sampling sites were selected randomly, comprehending lakes, bogs, small streams and river sections, all inserted in the four vegetation types occurring in the reserve. Fortysix species of Odonata were collected and grouped into 23 genera and seven families. The dominant families were Coenagrionidae (32%), Libellulidae (32%), Aeshnidae (12%), and, Calopterygidae and Lestidae (9%). As expected, the findings revealed the presence of a highly diverse Odonate assemblage, mainly represented by generalist species in the most human disturbed sectors (Pinus and Open fields) and some specialist species in the pristine forest. Two species were registered for the first time in the state of Rio Grande do Sul, Brazil: Libellula herculea Karsch, 1889 (Libellulidae) and Heteragrion luizfelipei Machado, 2006 (Heteragrionidae).

Reproductive success of wind, generalist, and specialist pollinated plant species following wildfire in desert landscapes

2017 ◽  
Vol 26 (12) ◽  
pp. 1030 ◽  
Author(s):  
Andrew H. Lybbert ◽  
Justin Taylor ◽  
Alysa DeFranco ◽  
Samuel B. St Clair
Keyword(s):  
Reproductive Success ◽  
Plant Species ◽  
Mojave Desert ◽  
Fruit Production ◽  
Native Plant ◽  
Pollination Services ◽  
Generalist Species ◽  
Plant Reproductive Success ◽  
Show Evidence ◽  
Specialist Species

Wildfire can drastically affect plant sexual reproductive success in plant–pollinator systems. We assessed plant reproductive success of wind, generalist and specialist pollinated plant species along paired unburned, burned-edge and burned-interior locations of large wildfires in the Mojave Desert. Flower production of wind and generalist pollinated plants was greater in burned landscapes than adjacent unburned areas, whereas specialist species responses were more neutral. Fruit production of generalist species was greater in burned landscapes than in unburned areas, whereas fruit production of wind- and specialist-pollinated species showed no difference in burned and unburned landscapes. Plants surviving in wildfire-disturbed landscapes did not show evidence of pollination failure, as measured by fruit set and seed:ovule ratios. Generalist- and specialist-plant species established in the interior of burned landscapes showed no difference in fruit production than plants established on burned edges suggesting that pollination services are conserved with increasing distance from fire boundaries in burned desert landscapes. Stimulation of plant reproduction in burned environments due to competition release may contribute to the maintenance of pollinator services and re-establishment of the native plant community in post-fire desert environments.

scholarly journals Mutation load dynamics during environmentally-driven range shifts

2018 ◽  
Author(s):  
Kimberly J. Gilbert ◽  
Stephan Peischl ◽  
Laurent Excoffier
Keyword(s):  
Environmental Change ◽  
Geographic Distance ◽  
Species Range ◽  
Range Shifts ◽  
Strong Impact ◽  
Generalist Species ◽  
Deleterious Alleles ◽  
Species Survival ◽  
Specialist Species ◽  
The Impact

AbstractThe fitness of spatially expanding species has been shown to decrease over time and space, but specialist species tracking their changing environment and shifting their range accordingly have been little studied. We use individual-based simulations and analytical modeling to compare the impact of range expansions and range shifts on genetic diversity and fitness loss, as well as the ability to recover fitness after either a shift or expansion. We find that the speed of a shift has a strong impact on fitness evolution. Fastest shifts show the strongest fitness loss per generation, but intermediate shift speeds lead to the strongest fitness loss per geographic distance. Range shifting species lose fitness more slowly through time than expanding species, however, their fitness compared at equivalent geographic distances spread can be considerably lower. These counter-intuitive results arise from the combination of time over which selection acts and mutations enter the system. Range shifts also exhibit reduced fitness recovery after a geographic shift and may result in extinction, whereas range expansions can persist from the core of the species range. The complexity of range expansions and range shifts highlights the potential for severe consequences of environmental change on species survival.Author SummaryAs environments change through time across the globe, species must adapt or relocate to survive. Specialized species must track the specific moving environments to which they are adapted, as compared to generalists which can spread widely. During colonization of new habitat, individuals can accumulate deleterious alleles through repeated bottlenecks. We show through simulation and analytic modeling that the process by which these alleles accumulate changes depending upon the speed at which populations spread over a landscape. This is due to the increased efficacy of selection against deleterious variants at slow speeds of range shifts and decreased input of mutations at faster speeds of range shifts. Under some selective circumstances, shifting of a species range leads to extinction of the entire population. This suggests that the rate of environmental change across the globe will play a large role in the survival of specialist species as compared to more generalist species.

scholarly journals GSAn: an alternative to enrichment analysis for annotating gene sets

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Aaron Ayllon-Benitez ◽  
Romain Bourqui ◽  
Patricia Thébault ◽  
Fleur Mougin
Keyword(s):  
Gene Ontology ◽  
Semantic Similarity ◽  
A Priori ◽  
Similarity Measures ◽  
Enrichment Analysis ◽  
Biological Information ◽  
Underlying Structure ◽  
Gene Set ◽  
Sequencing Technologies ◽  
Gene Coverage

Abstract The revolution in new sequencing technologies is greatly leading to new understandings of the relations between genotype and phenotype. To interpret and analyze data that are grouped according to a phenotype of interest, methods based on statistical enrichment became a standard in biology. However, these methods synthesize the biological information by a priori selecting the over-represented terms and may suffer from focusing on the most studied genes that represent a limited coverage of annotated genes within a gene set. Semantic similarity measures have shown great results within the pairwise gene comparison by making advantage of the underlying structure of the Gene Ontology. We developed GSAn, a novel gene set annotation method that uses semantic similarity measures to synthesize a priori Gene Ontology annotation terms. The originality of our approach is to identify the best compromise between the number of retained annotation terms that has to be drastically reduced and the number of related genes that has to be as large as possible. Moreover, GSAn offers interactive visualization facilities dedicated to the multi-scale analysis of gene set annotations. Compared to enrichment analysis tools, GSAn has shown excellent results in terms of maximizing the gene coverage while minimizing the number of terms.

THE FUTURE OF BIRCH FROM THE VIEWPOINT OF DISEASES AND INSECTS

1957 ◽  
Vol 33 (1) ◽  
pp. 25-30 ◽  
Author(s):  
D. R. Redmond
Keyword(s):  
Soil Temperature ◽  
High Grade ◽  
Forest Stands ◽  
Yellow Birch ◽  
Virus Diseases ◽  
Maritime Provinces ◽  
Eastern Canada ◽  
Important Species ◽  
Intensive Silviculture ◽  
Bronze Birch Borer

Yellow birch was once the most important species of hardwood in Eastern Canada. During the last 20 to 25 years, "birch dieback" has caused losses in the three Maritime Provinces estimated at 2,400 million cu. ft. A considerable number of species of insects feed normally on birch foliage, but none was found responsible for the disease. The bronze birch borer played a very important role in that its presence may have determined whether a tree succumbed to or recovered from decline. No fungi or bacteria found on twigs, leaves or roots were virulent enough to be considered the cause. No permanent or temporary stoppages were found in water-conducting tissues and occurrence of dieback has not been related to drought. Slight increases in soil temperature caused mortality of rootlets, which resulted in bare twigs, and small, slightly curled and chlorotic foliage. Several symptoms characteristic of virus diseases are being investigated. It is predicted that birch will form a substantial component of future forest stands, but high-grade products will be obtained only through application of intensive silviculture. Some recommended treatments are given.

Quantifying Neurotransmission Reliability Through Metrics-Based Information Analysis

2011 ◽  
Vol 23 (4) ◽  
pp. 852-881 ◽  
Author(s):  
Romain Brasselet ◽  
Roland S. Johansson ◽  
Angelo Arleo
Keyword(s):  
Spike Train ◽  
Information Transfer ◽  
A Priori ◽  
Similarity Measures ◽  
Conditional Entropy ◽  
Neural Population ◽  
Information Analysis ◽  
Full Account ◽  
Temporal Precision ◽  
Large Spike

We set forth an information-theoretical measure to quantify neurotransmission reliability while taking into full account the metrical properties of the spike train space. This parametric information analysis relies on similarity measures induced by the metrical relations between neural responses as spikes flow in. Thus, in order to assess the entropy, the conditional entropy, and the overall information transfer, this method does not require any a priori decoding algorithm to partition the space into equivalence classes. It therefore allows the optimal parameters of a class of distances to be determined with respect to information transmission. To validate the proposed information-theoretical approach, we study precise temporal decoding of human somatosensory signals recorded using microneurography experiments. For this analysis, we employ a similarity measure based on the Victor-Purpura spike train metrics. We show that with appropriate parameters of this distance, the relative spike times of the mechanoreceptors’ responses convey enough information to perform optimal discrimination—defined as maximum metrical information and zero conditional entropy—of 81 distinct stimuli within 40 ms of the first afferent spike. The proposed information-theoretical measure proves to be a suitable generalization of Shannon mutual information in order to consider the metrics of temporal codes explicitly. It allows neurotransmission reliability to be assessed in the presence of large spike train spaces (e.g., neural population codes) with high temporal precision.

scholarly journals Community structure of metazoan parasites of silverside, Odontesthes bonariensis (Pisces, Atherinopsidae) from Argentina

2012 ◽  
Vol 102 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Fabiana B. Drago
Keyword(s):  
Parasite Species ◽  
Host Record ◽  
Component Community ◽  
New Host ◽  
Metazoan Parasites ◽  
Generalist Species ◽  
New Host Record ◽  
Host Sex ◽  
Odontesthes Bonariensis ◽  
Specialist Species

The helminth communities of silverside, Odontesthes bonariensis (Valenciennes, 1835), from two Argentinean lagoons were studied and compared at component community and infracommunity levels. Nine helminth species were found: five digeneans (Austrodiplostomum cf. mordax, Ascocotyle (Phagicola) cf. diminuta, Ascocotyle sp., Thometrema bonariensis and Saccocoelioides sp.); two nematodes (Contracaecum sp. and Hysterothylacium sp.); one acanthocephalan (Wolffhugelia matercula) and one cestode (Cangatiella macdonaghi). Odontesthes bonariensis is a new host record for five parasite species. Richness, diversity and number of helminths in silversides from Salada Grande lagoon were higher than in those from Lacombe lagoon. This could be related with lagoon size, abundance of mollusks and fish-eating birds, and size and diet of silversides captured in each lagoon. In Salada Grande lagoon the helminth community of silversides was dominated by the allogenic and generalist species A. cf. mordax; while the autogenic and intermediate specialist species C. macdonaghi was dominant in Lacombe lagoon. Host sex did not affect richness, diversity or total abundance, whereas host size was positively correlated with these attributes, except diversity in Salada Grande lagoon.

scholarly journals Group selection harvesting supports diversity of forest specialist carabids

2019 ◽  
Vol 2 ◽  
Author(s):  
Bela Tóthmérész ◽  
Tibor Magura ◽  
Szabolcs Mizser ◽  
David D. Nagy
Keyword(s):  
Forest Management ◽  
Group Selection ◽  
Environmental Changes ◽  
Control Area ◽  
Oak Forests ◽  
Pitfall Traps ◽  
Clear Cut ◽  
Clear Cutting ◽  
Specialist Species ◽  
Selection Harvesting

Increased fragmentation and considerable environmental changes in native forests caused by the timber-oriented forest managements are threatening the biodiversity of forests. As a remediation, uneven-aged approach is recommended during forest management, because this is less intensive and could be less harmful than even-aged practices. We tested the effects of clear-cutting (as even-aged method) and group selection harvesting (as uneven-aged method) on carabids in lowland oak forests. Pitfall traps and litter sifting were used during the study. We found that the total number of species was significantly higher in the gaps harvested by group selection and in the clear-cut than in the mature forests (control area). The species richness of forest specialist species was significantly lower in the clear-cuts than in the other area. Our findings demonstrated that the conventional clear-cutting caused a decrease in the number of forest specialist species. Therefore, group selection method should be favoured during forest management to maintain diversity.

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