Bat flies aggregation onArtibeus planirostrishosts in the Pantanal floodplain and surrounding plateaus

Parasitology ◽  
2019 ◽  
Vol 146 (11) ◽  
pp. 1462-1466 ◽  
Author(s):  
Esther Gonçalves Morimatsu Vieira ◽  
Erich Fischer ◽  
Gustavo Graciolli ◽  
Carolina Ferreira Santos ◽  
George Camargo ◽  
...  
Keyword(s):  
Host Susceptibility ◽  
Common Pattern ◽  
Aggregation Index ◽  
Natural Systems ◽  
Bat Flies ◽  
Rock Formations ◽  
Aggregation Pattern ◽  
Parasite Aggregation ◽  
D Values ◽  
Main Factor

AbstractFor parasites in natural systems, the most common pattern of spatial distribution is aggregation among hosts. The main causes of such aggregation are variable exposure of hosts to parasites and heterogeneity in host susceptibility. The objective of this study was to determine if there are differences in the aggregation pattern of two species of ectoparasitic flies between the Pantanal and Cerrado regions of Brazil on the batArtibeus planirostris.We collected the ectoparasites from bats captured between 2002 and 2017 with mist nets in 21 sites in the Pantanal and 15 sites in the surrounding plateaus. The results showed that the aggregation of ectoparasitic flies in Pantanal was more pronounced than in Cerrado. The discrepancy aggregation index (D) of the bat flyMegistopoda araneawas 0.877 in Pantanal and 0.724 in Cerrado. The D values ofAspidoptera phyllostomatiswas even higher, with 0.916 and 0.848 in the Pantanal and Cerrado, respectively. Differences in the shelters used may be the main factor shaping variation in aggregation, since the Pantanal does not have rock formations, with only foliage, crowns and hollow tree trunks. These differences likely affect host exposure to the parasites, leading to an increase in parasite aggregation.

Explaining variability in parasite aggregation levels among host samples

Parasitology ◽  
2013 ◽  
Vol 140 (4) ◽  
pp. 541-546 ◽  
Author(s):  
ROBERT POULIN
Keyword(s):  
Body Size ◽  
Strong Relationship ◽  
Host Susceptibility ◽  
Helminth Parasites ◽  
Susceptibility To Infection ◽  
Host Body ◽  
Parasite Aggregation ◽  
Using Data ◽  
Species Specific ◽  
Host Body Size

SUMMARYAggregated distributions among individual hosts are a defining feature of metazoan parasite populations. Heterogeneity among host individuals in exposure to parasites or in susceptibility to infection is thought to be the main factor generating aggregation, with properties of parasites themselves explaining some of the variability in aggregation levels observed among species. Here, using data from 410 samples of helminth parasites on fish hosts, I tested the contribution of (i) within-sample variation in host body size, taken as a proxy for variability in host susceptibility, and (ii) parasite taxon and developmental stage, to the aggregated distribution of parasites. Log-transformed variance in numbers of parasites per host was regressed against log mean number across all samples; the strong relationship (r2 = 0·88) indicated that aggregation levels are tightly constrained by mean infection levels, and that only a small proportion of the observed variability in parasite aggregation levels remains to be accounted for by other factors. Using the residuals of this regression as measures of ‘unexplained’ aggregation, a mixed effects model revealed no significant effect of within-sample variation in host body size or of parasite taxon or stage (i.e. juvenile versus adult) on parasite aggregation level within a sample. However, much of the remaining variability in parasite aggregation levels among samples was accounted for by the number of individual hosts examined per sample, and species-specific and study-specific effects reflecting idiosyncrasies of particular systems. This suggests that with most differences in aggregation among samples already explained, there may be little point in seeking universal causes for the remaining variation.

scholarly journals Populational Structure of Eugenia sp. in Paraban Semiarid of State, Brazil

2019 ◽  
pp. 1-5
Author(s):  
André Japiassú ◽  
Josimar Gomes Dantas ◽  
Francisco de Oliveira Mesquita ◽  
Adriana Araújo Diniz ◽  
Anailson de Sousa Alevs ◽  
...  
Keyword(s):  
Basal Area ◽  
Ground Level ◽  
Aggregation Index ◽  
Aggregation Pattern ◽  
Disturbed Areas ◽  
Cluster Area ◽  
Absolute Density ◽  
History Of ◽  
Number Of Individuals ◽  
Vegetation Mosaics

The genus Eugenia presents one of the most important in Myrtaceae family, expressing a potential nutritional high and in drugs obtaining. The plants are resist and resist disease, their hardwood has been used to produce posts, stakes, poles, firewood and charcoal. The objective of this present work was to conduct a survey of the population structure of Eugenia sp. was conducted in caatinga area, located in the municipality of Caturité, PB. Were sampled Forty plots of 10x20 m, totaling a sample area of 8.000 m². All shrub-tree individuals were inventoried by the taking the ground level diameter (DNS), height and number of tillers. The vegetation structure was evaluated by basal area, absolute density, absolute frequency and aggregation index of the species. A total of 741 individuals of Eugenia sp. Distributed in four vegetation mosaics with a history of different uses, which were conventionally approached as: A I = Abandoned quarry area; A II = Bottom of the valley; A III = Conserved Area and A IV = Capoeira Area. Area I presented a total of 92 individuals sampled in the 10 experimental plots (DA = 460), where in this environment the species tended to cluster, Area II presented 124 individuals (DA = 620) and the McGuines index expressed that in this environment the species finds grouped. In Area III, 480 individuals were sampled with an absolute density of 2,400 ind. ha-1 grouped. The density of Eugenia sp. Was performed descriptive statistical analysis. It is different in vegetation mosaics due to the history of land use in the studied areas. The largest number of individuals of Eugenia sp. is concentrated in the conserved area showing aggregation pattern. In all areas of study, individuals have low stem diameter, expressing the importance of the species in the regeneration of disturbed areas. In the quarry area are the individuals with higher height.

Infection, specificity and host manipulation of Australapatemon sp. (Trematoda, Strigeidae) in two sympatric species of leeches (Hirudinea)

Parasitology ◽  
2017 ◽  
Vol 144 (10) ◽  
pp. 1346-1355
Author(s):  
ANSSI KARVONEN ◽  
ANNA FALTÝNKOVÁ ◽  
JOCELYN MAH CHOO ◽  
E. TELLERVO VALTONEN
Keyword(s):  
Host Species ◽  
Spatial Scales ◽  
Sympatric Species ◽  
Life Cycles ◽  
Host Susceptibility ◽  
Avian Host ◽  
Natural Systems ◽  
Interspecific Differences ◽  
Infection Dynamics ◽  
Host Parasite

SUMMARYFactors that drive parasite specificity and differences in infection dynamics among alternative host species are important for ecology and evolution of host–parasite interactions, but still often poorly known in natural systems. Here, we investigated spatiotemporal dynamics of infection, host susceptibility and parasite-induced changes in host phenotype in a rarely explored host–parasite system, the Australapatemon sp. trematode infecting two sympatric species of freshwater leeches, Erpobdella octoculata and Helobdella stagnalis. We show significant variation in infection abundance between the host species in both space and time. Using experimental infections, we also show that most of this variation likely comes from interspecific differences in exposure rather than susceptibility. Moreover, we demonstrate that the hiding behaviour of E. octoculata, but not that of H. stagnalis, was impaired by the infection irrespective of the parasite abundance. This may increase susceptibility of E. octoculata to predation by the final avian host. We conclude that differences in patterns of infection and in behavioural alterations among alternative sympatric host species may arise in narrow spatial scales, which emphasises the importance of local infection and transmission dynamics for parasite life cycles.

Degree of tapering of xylem conduits in stems and roots of small Pinus cembra and Larix decidua trees

Botany ◽  
2009 ◽  
Vol 87 (5) ◽  
pp. 501-508 ◽  
Author(s):  
Giai Petit ◽  
Tommaso Anfodillo ◽  
Carlo De Zan
Keyword(s):  
Tree Height ◽  
Considerable Effect ◽  
Larix Decidua ◽  
Subalpine Forest ◽  
Forest Age ◽  
Pinus Cembra ◽  
Root Tips ◽  
Common Pattern ◽  
Xylem Conduits ◽  
Main Factor

Xylem conduits increase in size from the apex downwards. While conduit tapering in the stem has often been reported to converge towards a common pattern among all plants, information on conduit tapering in small plants and roots is extremely scarce. We selected 10 small trees (height < 3 m) of Pinus cembra  L. and Larix decidua Miller along an altitudinal gradient and measured diameter and conduit dimensions along stems and roots in the last annual ring. Sections of 10 µm were cut from wooden disks taken at different heights in the stem and in the roots and then stained with safranine. Slides were observed under a microscope, the lumen areas of conduits were measured and mean hydraulic diameters (Dh) calculated. Dh increased from stem tip (Dh at 1 cm from the apex averaged 10.75 µm; s = 2.33) to base (Dh from 20.70 to 30.54 µm), following a power trajectory (i.e., Dh = a·Lb, with L being the distance from the tip). Such degrees of conduit tapering may have a considerable effect in minimizing the hydraulic constraints. Despite trees at the treeline being older and smaller than in the subalpine forest (age: 28–70 years at the treeline; 18–39 years in the subalpine forest), conduit tapering did not differ significantly between sites, suggesting that tree height is the main factor controlling the basipetal increase in conduit lumens. In the roots, the increase in conduit dimensions continued towards their tips, even more steeply than in the stem. The widest conduits were measured around the root tips (around 40 µm). Conduit tapering resulted as a stable structural feature in small plants as well as in tall trees.

A new model explaining the origin of different topologies in interaction networks

2018 ◽  
Author(s):  
Rafael B. P. Pinheiro ◽  
Gabriel M. F. Félix ◽  
Carsten F. Dormann ◽  
Marco A. R. Mello
Keyword(s):  
First Principles ◽  
Mechanistic Model ◽  
Interaction Networks ◽  
Natural Systems ◽  
The Past ◽  
Trade Offs ◽  
Key Factor ◽  
Resource Networks ◽  
Consumer Resource ◽  
Main Factor

AbstractThe architecture of interaction networks has been extensively studied in the past decades, and different topologies have been observed in natural systems. Despite several phenomenological explanations proposed, we still understand little of the mechanisms that generate those topologies. Here we present a mechanistic model based on the integrative hypothesis of specialization, which aims at explaining the emergence of topology and specialization in consumer-resource networks. By following three first-principles and adjusting five parameters, our model was able to generate synthetic weighted networks that show the main patterns of topology and specialization observed in nature. Our results prove that topology emergence is possible without network-level selection. In our simulations, the intensity of trade-offs in the performance of each consumer species on different resource species is the main factor driving network topology. We predict that interaction networks with low species diversity and low dissimilarity between resources should have a nested topology, although more diverse networks with large dissimilarity should have a compound topology. Additionally, our results highlight scale as a key factor. Our model generates predictions consistent with ecological and evolutionary theories and real-world observations. Therefore, it supports the IHS as a useful conceptual framework to study the architecture of interaction networks.

Aggregation and dispersion of krill at channel heads and shelf edges: the dynamics in the Saguenay - St. Lawrence Marine Park

2000 ◽  
Vol 57 (9) ◽  
pp. 1853-1869 ◽  
Author(s):  
Diane Lavoie ◽  
Yvan Simard ◽  
François J Saucier
Keyword(s):  
Spatial Organization ◽  
Three Dimensional ◽  
Circulation Model ◽  
Baleen Whales ◽  
Marine Park ◽  
Aggregation Pattern ◽  
Pile Up ◽  
Northern Edge ◽  
Abundance And Distribution ◽  
Main Factor

The spatial organization of the euphausiid (Thysanoessa raschi and Meganyctiphanes norvegica) aggregation at the head of the Laurentian Channel is examined using 120-kHz echointegration data from eight surveys in the summers of 1994 and 1995 and currents obtained from a high-resolution three-dimensional circulation model. Circulation is the main factor controlling the abundance and distribution of krill. The main aggregation pattern is U-shaped and includes an entrance corridor along the northern edge of the channel, a major accumulation zone off Les Escoumins, and an exit corridor along the southern edge. However, this mesoscale aggregation exhibits rapid fluctuations in spatial pattern and global abundance, due to the redistribution of krill within and out of the study area. The local accumulations are controlled by the interactions between the semidiurnal tidal currents, the topography, and the negative phototactism of krill. The strong vertical currents found along the channel slopes upstream of Les Escoumins and at the sills act to concentrate and pile up krill. The aggregation and dispersion mechanisms are strongly influenced by the deepwater blocking process taking place at the sills. The fortnightly tidal cycle and freshwater runoff modulate the blocking intensity. This krill aggregation dynamics is of primary importance for the trophic link with the baleen whales and fish in the Saguenay - St. Lawrence Marine Park.

Application of a Simple Cold Stub to the Direct Observation of Frozen Hydrated Sand

1973 ◽  
Vol 31 ◽  
pp. 212-213
Author(s):  
John M. Wehrung ◽  
Richard J. Harniman
Keyword(s):  
United States ◽  
Surface Water ◽  
Direct Observation ◽  
Controlled Study ◽  
Clay Particles ◽  
Organic Debris ◽  
Rock Formations ◽  
Water Tables ◽  
Permeable Rock ◽  
Natural Means

Water tables in aquifer regions of the southwest United States are dropping off at a rate which is greater than can be replaced by natural means. It is estimated that by 1985 wells will run dry in this region unless adequate artificial recharging can be accomplished. Recharging with surface water is limited by the plugging of permeable rock formations underground by clay particles and organic debris.A controlled study was initiated in which sand grains were used as the rock formation and water with known clay concentrations as the recharge media. The plugging mechanism was investigated by direct observation in the SEM of frozen hydrated sand samples from selected depths.

Effect of Iron Limitation on the Ultrastructure of Agmenellum Quadruplicatum

1981 ◽  
Vol 39 ◽  
pp. 410-411
Author(s):  
L. P. Hardie ◽  
D. L. Balkwill ◽  
S. E. Stevens
Keyword(s):  
Growth Medium ◽  
Green Alga ◽  
Natural Habitat ◽  
Iron Limitation ◽  
Natural Environments ◽  
Blue Green Alga ◽  
Marine Cyanobacterium ◽  
Natural Systems ◽  
Thin Sectioning ◽  
Agmenellum Quadruplicatum

Agmenellum quadruplicatum is a unicellular, non-nitrogen-fixing, marine cyanobacterium (blue-green alga). The ultrastructure of this organism, when grown in the laboratory with all necessary nutrients, has been characterized thoroughly. In contrast, little is known of its ultrastructure in the specific nutrient-limiting conditions typical of its natural habitat. Iron is one of the nutrients likely to limit this organism in such natural environments. It is also of great importance metabolically, being required for both photosynthesis and assimilation of nitrate. The purpose of this study was to assess the effects (if any) of iron limitation on the ultrastructure of A. quadruplicatum. It was part of a broader endeavor to elucidate the ultrastructure of cyanobacteria in natural systemsActively growing cells were placed in a growth medium containing 1% of its usual iron. The cultures were then sampled periodically for 10 days and prepared for thin sectioning TEM to assess the effects of iron limitation.

Rapeseed Oil and Sunflower Oil Diets Enhance Platelet In Vitro Aggregation and Thromboxane Production in Healthy Men when Compared with Milk Fat or Habitual Diets

1992 ◽  
Vol 67 (03) ◽  
pp. 352-356 ◽  
Author(s):  
Marja Mutanen ◽  
Riitta Freese ◽  
Liisa M Valsta ◽  
Irma Ahola ◽  
Antti Ahlström
Keyword(s):  
Sunflower Oil ◽  
Milk Fat ◽  
Rapeseed Oil ◽  
Controlled Trial ◽  
Collagen Concentration ◽  
Aggregation Pattern ◽  
Thromboxane Production ◽  
Low Erucic Acid ◽  
Platelet Thromboxane

SummaryIn this highly controlled trial, 26 normolipidemic men (average age 28 years, range 18 to 60) were fed a baseline diet high in milk fat (MF) (fat 36% of energy, saturates 19%, monounsaturates 11%, polyunsaturates 4%), followed by a diet high in sunflower oil (SO) (fat 38% of energy, saturates 13%, monounsaturates 10%, polyunsaturates 13%) and another diet high in low erucic-acid rapeseed oil (RO) (fat 38% of energy, saturates 12%, monounsaturates 16%, polyunsaturates 8%). All diets were mixed natural diets with the same cholesterol contents. The baseline milk fat diet was given for 14 days and the oil diets for 24 days in a blind cross-over design. The platelet in vitro aggregation (slope %/min) induced by 1, 2 and 3 pM ADP and collagen (25 pg/ml PRP) was highly significantly (p <0.001) increased after both oil diets when compared with the results from the milk fat diet. The aggregation pattern determined by threshold collagen concentration confirmed increased collagen sensitivity of the platelets after the rapeseed oil diet (p <0.001). The enhancement of platelet aggregation was associated with increased in vitro platelet thromboxane production after the oil diets vs. the milk fat diet (p <0.05 after the sunflower oil diet and p <0.001 after the rapeseed oil diet).

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