scholarly journals Human pathogen co-occurrence in Ixodes ricinus ticks: effects of landscape topography, climatic factors and microbiota interactions

2019 ◽  
Author(s):  
Tuomas Aivelo ◽  
Anna Norberg ◽  
Barbara Tschirren
Keyword(s):  
Ixodes Ricinus ◽  
Species Distribution Model ◽  
Climatic Factors ◽  
Vector Competence ◽  
Environmental Filtering ◽  
Ecological Factors ◽  
Swiss Alps ◽  
Distribution Model ◽  
Human Pathogens ◽  
Competition Effects

AbstractThe factors shaping microbial communities within organisms are still poorly understood. Besides ecological factors and host characteristics, direct interactions among microbes may shape the occurrence of microbes and the structure of communities. In the past it has been difficult to disentangle if patterns of microbial co-occurrence are due to facilitation or competition effects, or shaped by shared ecological preferences (i.e., environmental filtering). Here we use a joint species distribution model to characterize the bacterial microbiota composition of an important human disease vector, the sheep tick Ixodes ricinus, along ecological gradients in the Swiss Alps, and to test for facilitation or competition effects among human pathogens and tick endosymbionts. We identify a number of ecological variables that significantly predicted the diversity of tick microbial community and the occurrence of specific tick endosymbionts and human pathogens. However, ecological associations were generally microbe-specific rather than universal. We also found evidence for significant microbe interactions, in particular widespread facilitation among pathogens, which promotes pathogen co-infection within ticks, as well as competition between the tick endosymbiont Spiroplasma and a number of human pathogens. These findings highlight that direct interactions among microbes can affect the vector competence of ticks and thereby tick-borne disease dynamics.

scholarly journals Bacterial microbiota composition of Ixodes ricinus ticks: the role of environmental variation, tick characteristics and microbial interactions

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8217 ◽  
Author(s):  
Tuomas Aivelo ◽  
Anna Norberg ◽  
Barbara Tschirren
Keyword(s):  
Microbial Communities ◽  
Ixodes Ricinus ◽  
Ecological Factors ◽  
Environmental Variation ◽  
Swiss Alps ◽  
Small Scale ◽  
Human Pathogens ◽  
Environmental Preferences ◽  
Bacterial Microbiota

Ecological factors, host characteristics and/or interactions among microbes may all shape the occurrence of microbes and the structure of microbial communities within organisms. In the past, disentangling these factors and determining their relative importance in shaping within-host microbiota communities has been hampered by analytical limitations to account for (dis)similar environmental preferences (‘environmental filtering’). Here we used a joint species distribution modelling (JSDM) approach to characterize the bacterial microbiota of one of the most important disease vectors in Europe, the sheep tick Ixodes ricinus, along ecological gradients in the Swiss Alps. Although our study captured extensive environmental variation along elevational clines, the explanatory power of such large-scale ecological factors was comparably weak, suggesting that tick-specific traits and behaviours, microhabitat and -climate experienced by ticks, and interactions among microbes play an important role in shaping tick microbial communities. Indeed, when accounting for shared environmental preferences, evidence for significant patterns of positive or negative co-occurrence among microbes was found, which is indicative of competition or facilitation processes. Signals of facilitation were observed primarily among human pathogens, leading to co-infection within ticks, whereas signals of competition were observed between the tick endosymbiont Spiroplasma and human pathogens. These findings highlight the important role of small-scale ecological variation and microbe-microbe interactions in shaping tick microbial communities and the dynamics of tick-borne disease.

scholarly journals Do priority effects outweigh environmental filtering in a guild of dominant freshwater macroinvertebrates?

2017 ◽  
Author(s):  
Chelsea J. Little ◽  
Florian Altermatt
Keyword(s):  
Species Distribution Model ◽  
Environmental Filtering ◽  
Biotic Interactions ◽  
Priority Effects ◽  
Distribution Model ◽  
Amphipod Species ◽  
Macroinvertebrate Communities ◽  
Field Evidence ◽  
Equal Importance ◽  
Environmental Requirements

AbstractAbiotic conditions have long been considered essential in structuring freshwater macroinvertebrate communities. Ecological drift, dispersal, and biotic interactions also structure communities, and although these mechanisms are more difficult to detect, they may be of equal importance in natural communities. Here, we conducted repeated surveys of locally-dominant amphipod species across ten naturally replicated stream catchments. We then used a hierarchical joint species distribution model to assess the influence of different drivers on species co-occurrences. The species had unique environmental requirements, but a distinct spatial structure in their distributions was unrelated to habitat. Species co-occurred much less frequently than predicted by their niches, which was surprising because laboratory and field evidence suggests they are capable of coexisting in equal densities. We suggest that niche preemption may limit their distribution and that a blocking effect determines which species colonizes and dominates a given stream catchment, thus resolving a long-standing conundrum in freshwater ecology.

scholarly journals Species distribution model for Buxbaumia viridis, identifying new areas of presumed distribution in the Czech Republic.

2020 ◽  
Vol 69 (1) ◽  
pp. 21-28
Author(s):  
Lukáš Číhal ◽  
Lucie Fialová ◽  
Vítězslav Plášek
Keyword(s):  
Air Pollution ◽  
Czech Republic ◽  
Species Distribution ◽  
Species Distribution Model ◽  
Ecological Factors ◽  
Field Research ◽  
Distribution Model ◽  
Distribution Models ◽  
The Czech Republic ◽  
The Subject

Abstract There is a large number of organisms in nature that are hard to find in the field, and one of these is also a rare bryophyte species, Buxbaumia viridis, which can also only be found in a certain part of the year in the production of sporophytes. Using distribution models, however, it is possible to predict the locations which this species is likely to be present at and to focus the field research directly on such sites. Thanks to the presented model, we have succeeded in identifying areas within the Czech Republic with an increased likelihood of its occurrence, even in some areas where no collection of B. viridis has so far been recorded. With the help of the maps created these locations can be identified with the accuracy of approximately 1 km2, making it easier for terrain research and resulting time and often financial expenses. We have also focused on the study of ecological factors that influence the occurrence of the species, and by testing variables from different categories we have come to some agreement with previously published studies. Whilst we have managed to exclude that air pollution has a major role to its occurrence, which has not yet been the subject of any study.

scholarly journals Do priority effects outweigh environmental filtering in a guild of dominant freshwater macroinvertebrates?

2018 ◽  
Vol 285 (1876) ◽  
pp. 20180205 ◽  
Author(s):  
Chelsea J. Little ◽  
Florian Altermatt
Keyword(s):  
Species Distribution Model ◽  
Environmental Filtering ◽  
Biotic Interactions ◽  
Priority Effects ◽  
Distribution Model ◽  
Amphipod Species ◽  
Macroinvertebrate Communities ◽  
Field Evidence ◽  
Equal Importance ◽  
Linear Configuration

Abiotic conditions have long been considered essential in structuring freshwater macroinvertebrate communities. Ecological drift, dispersal and biotic interactions also structure communities, and although these mechanisms are more difficult to detect, they may be of equal importance in natural communities. Here, we hypothesized that in 10 naturally replicated headwater streams in eastern Switzerland, locally dominant amphipod species would be associated with differences in environmental conditions. We conducted repeated surveys of amphipods and used a hierarchical joint species distribution model to assess the influence of different drivers on species co-occurrences. The species had unique environmental requirements, but a distinct spatial structure in their distributions was unrelated to habitat. Species co-occurred much less frequently than predicted by the model, which was surprising because laboratory and field evidence suggests they are capable of coexisting in equal densities. We suggest that niche preemption may limit their distribution and that a blocking effect related to the specific linear configuration of streams determines which species colonizes and dominates a given stream catchment, thus suggesting a new solution a long-standing conundrum in freshwater ecology.

scholarly journals A Robust Prediction Model for Species Distribution Using Bagging Ensembles with Deep Neural Networks

2021 ◽  
Vol 13 (8) ◽  
pp. 1495
Author(s):  
Jehyeok Rew ◽  
Yongjang Cho ◽  
Eenjun Hwang
Keyword(s):  
Neural Networks ◽  
Species Distribution ◽  
Best Practice ◽  
Deep Neural Networks ◽  
Species Distribution Models ◽  
Species Distribution Model ◽  
Environmental Data ◽  
Distribution Model ◽  
Distribution Models ◽  
Robust Prediction

Species distribution models have been used for various purposes, such as conserving species, discovering potential habitats, and obtaining evolutionary insights by predicting species occurrence. Many statistical and machine-learning-based approaches have been proposed to construct effective species distribution models, but with limited success due to spatial biases in presences and imbalanced presence-absences. We propose a novel species distribution model to address these problems based on bootstrap aggregating (bagging) ensembles of deep neural networks (DNNs). We first generate bootstraps considering presence-absence data on spatial balance to alleviate the bias problem. Then we construct DNNs using environmental data from presence and absence locations, and finally combine these into an ensemble model using three voting methods to improve prediction accuracy. Extensive experiments verified the proposed model’s effectiveness for species in South Korea using crowdsourced observations that have spatial biases. The proposed model achieved more accurate and robust prediction results than the current best practice models.

scholarly journals A Bioclimate-Based Maximum Entropy Model for Comperiella calauanica Barrion, Almarinez and Amalin (Hymenoptera: Encyrtidae) in the Philippines

Insects ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 26
Author(s):  
Billy Joel M. Almarinez ◽  
Mary Jane A. Fadri ◽  
Richard Lasina ◽  
Mary Angelique A. Tavera ◽  
Thaddeus M. Carvajal ◽  
...  
Keyword(s):  
Maximum Entropy ◽  
Habitat Suitability ◽  
Species Distribution Model ◽  
Biological Control Agent ◽  
The Philippines ◽  
Distribution Model ◽  
Field Surveys ◽  
Probability Of Occurrence ◽  
Precipitation Seasonality ◽  
Bioclimatic Variables

Comperiella calauanica is a host-specific endoparasitoid and effective biological control agent of the diaspidid Aspidiotus rigidus, whose outbreak from 2010 to 2015 severely threatened the coconut industry in the Philippines. Using the maximum entropy (Maxent) algorithm, we developed a species distribution model (SDM) for C. calauanica based on 19 bioclimatic variables, using occurrence data obtained mostly from field surveys conducted in A. rigidus-infested areas in Luzon Island from 2014 to 2016. The calculated the area under the ROC curve (AUC) values for the model were very high (0.966, standard deviation = 0.005), indicating the model’s high predictive power. Precipitation seasonality was found to have the highest relative contribution to model development. Response curves produced by Maxent suggested the positive influence of mean temperature of the driest quarter, and negative influence of precipitation of the driest and coldest quarters on habitat suitability. Given that C. calauanica has been found to always occur with A. rigidus in Luzon Island due to high host-specificity, the SDM for the parasitoid may also be considered and used as a predictive model for its host. This was confirmed through field surveys conducted between late 2016 and early 2018, which found and confirmed the occurrence of A. rigidus in three areas predicted by the SDM to have moderate to high habitat suitability or probability of occurrence of C. calauanica: Zamboanga City in Mindanao; Isabela City in Basilan Island; and Tablas Island in Romblon. This validation in the field demonstrated the utility of the bioclimate-based SDM for C. calauanica in predicting habitat suitability or probability of occurrence of A. rigidus in the Philippines.

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