152 research outputs found
Modelação espacial da adequabilidade de habitat a espécies invasoras: o Carpobrotus Edulis em terreno não dunar
SPATIAL MODELLING OF HABITAT SUITABILITY FOR INVASIVE SPECIES: THE CARPOBROTUS EDULIS IN A NON-DUNE AREA. The use of habitat modelling for exotic invasive species can be extremely useful for identifying their potential impacts and for assisting in the design of eradication strategies. Even though the latter builds on theoretical assumptions that are quite different from those involved in the modelling of the habitat of native species, these two modelling methods are in fact quite similar. This article presents a habitat suitability modelling framework for Carpobrotus edulis, an alien invader plant in Serra do Bouro, Portugal. Several land surveys have been carried out in the study area in order to record the presence of this plant. The criteria for recording a presence were that the plant did not show any signs of weakness and that there were mat formations covering at least 5m2. Pseudo-absences were also obtained in a completely random way. The model was calibrated using a binary logistic regression. The performance of this model usually considered superior to that of models that rely on presence data only. Additionally, an evaluation technique based on the minimum area of higher adequacy is also presented. This technique assumes that, for a given probability threshold, model performance is higher whenever it has the same number of correct presences for a smaller predicted area. Using a 0.7 probability threshold, the model correctly predicted 80% of the total presences using only 8% of the study area. The model suggests that the main factor contributing to the expansion of Carpobrotus edulis has been the abandonment of agriculture in the study area. In addition, proximity to the shoreline and above-average erosion potential in the study area both seem to benefit the plant’s expansion. Conversely, steeper and longer slopes, and greater distances from the shoreline, were found to be significant contributors to the plant’s absence
Modeling the distribution of Aedes Albopictus in European main Urban Areas
The mosquito Aedes albopictus has been dispersed worldwide by human activities. This species
is an important vector of arboviruses, including dengue, chikungunya and Zika and is now one of the
greatest threats to global public health. Due to the medical importance of this species, previous studies
have examined its ecological requirements and predicted its potential distribution for various regions
of the world. However, to date, there is no attempt to perform such analyses across European cities
and at a high spatial detail. Hence, in this work we aim to fill this gap by modelling the potential
distribution of the species across the major functional urban areas of Europe, using high resolution
predictors. The modelling tested for associations between the observed distribution of the species and
spatial variables considered relevant in determining its distribution, particularly climate and land use.
Complementary models also examined the possibility of spatial bias in the mosquito distribution data
as driven simply by higher human observational capacity. Model results suggest the absence of
significant observational bias and that densely urbanized urban together with higher temperatures and
water availability in drier months favor the occurrence of the species. The models were also applied to
predict areas under susceptibility of establishment of the species in Lisbon, a city where the species
has not yet been observed. From this prediction we found that the areas under higher susceptibility are
mainly associated to the urban centers, whereas green areas, most notably Monsanto Park, are least
susceptible. Finally, we developed a risk map, resulting from the intersection of susceptibility and
human population, which allowed pinpointing the areas in the city where the threats inflicted by the
species are higher.info:eu-repo/semantics/publishedVersio
Automated cleansing and harmonization of international trade data
Large volumes of data are becoming increasingly available and can be very valuable for the analysis of different phenomena. These data can originate from multiple sources and be recorded in diverse formats, requiring preliminary scrutiny in order to be further used in scientific analyses. This first crucial phase of filtering and cleansing data is usually a cumbersome and time-consuming task, but automated routines can be developed to help researchers. A routine created with the R language is here presented, to screen, harmonize and aggregate international trade data, representing the trade flows between countries for specific products, in a timeframe that covers monthly flows for at least 15 years for most countries. The R script implementing these routines is provided, being easily adapted to other datasets with similar issues.
• A step-by-step procedure for cleansing and harmonizing international trade data, using R programming language, is presented
• Automated routines are very effective in obtaining robust and filtered data inputs to integrate in scientific models
• Spatial and temporal patterns of worldwide trade relations can be explored to enhance our understanding of various associated phenomenainfo:eu-repo/semantics/publishedVersio
The susceptibility of urban areas in Europe to vector-borne diseases spread by the Asian Tiger mosquito
The Asian tiger mosquito (Aedes albopictus) is now present in nearly all continentspresent in all
populated continents and it is widening its range in temperate regions. As a competent vector to
numerous diseases, including dengue, Zika and Chikungunya viruses, public health concerns have
encouraged intense research and modelling efforts to assess the suitability to the mosquito in different
regions. We evaluated the level of consensus between several model results covering Europe, to identify
hotspots of high and low suitability, as well as the areas with higher uncertainty. We analysed the
possible variations of suitability levels between present-day and future climatic conditions and identified
9 potential trajectories. Results show strong inter-model consensus regarding the future expansion of
the mosquito to northern and eastern Europe, with suitable areas with low uncertainty covering 70% of
the study area, whereas no decrease in suitability is expected. We analysed the potential trajectories for
65 large urban areas and found that 83% are predicted suitable to the introduction of the mosquito in
the future. Cities located in northern Europe show the most drastic changes, varying from currently
unsuitable to certainly suitable. None of the cities analysed is predicted as unsuitable in future climatic
scenarios. These results can help defining research pathways for further modelling efforts and show the
importance of planning for vector surveillance and control, even in places where Ae. albopictus and the
risk of vector-borne diseases is currently absent but is expected to increase in future.info:eu-repo/semantics/publishedVersio
Human‐induced globalization of insular herpetofaunas
Aim: The aim was to document the impact of the globalization of human activity
on the biodiversity and biogeographical patterns of reptilian and amphibian faunas
across islands worldwide.
Location: Islands worldwide.
Time period: From the 15th century to the present time.
Major taxa studied: Reptiles and amphibians.
Methods: We compiled lists of the reptilian and amphibian species that occurred on
islands before the 15th century and of those that occur currently. For each species
group, we calculated differences in species richness and in compositional similarities among islands, between the two periods. Regression models were used: (a) to
associate the observed differences with spatial patterns of geographical, climatic,
biotic and human factors; and (b) to quantify changes in the relative importance of
non-human factors in explaining the spatial patterns of species richness and compositional similarity.
Results: The richness of reptile and amphibian species increased consistently across
islands worldwide. Hotspots of increase were detected in the Caribbean and the
Indian Ocean. The composition of species assemblages was substantially homogenized; this was particularly true for amphibians within the Caribbean Sea and for
reptiles within the Caribbean Sea and Indian Ocean and between the Indian and the
Pacific Oceans. Our results showed that spatial patterns of change in species richness
and compositional similarity are driven by human and natural factors. The driving role
of mean annual temperature is particularly consistent, and current reptile richness
and compositional similarity patterns for both species groups are increasingly being
shaped by the global temperature gradient.
Main conclusions: The globalization of human activity is eroding the regionalized
character of insular herpetofaunas and leading to the emergence of global-scale gradients of taxonomic composition and species richness. Projections of increasing rates
of biological invasions, extinctions and climate change suggest that these changes are
likely to be aggravated even further in the coming decadesinfo:eu-repo/semantics/acceptedVersio
Assessing the current and future suitability to the Asian Tiger mosquito, a dengue and Zika vector, in major cities in Europe
The Asian tiger mosquito (Aedes albopictus) is a competent vector of numerous
diseases, including the dengue and Zika viruses, and public health concerns have
encouraged extensive research to model the environmental suitability to the mosquito.
We evaluated the level of consensus between published predictions for the European
continent and for a set of 65 major cities. We identified consensus hotspots of high and
low suitability and the potential variations of suitability levels between present-day and
future climatic conditions. A strong inter-model agreement was found regarding the
future expansion of the mosquito to northern and eastern Europe. About 83% of cities
are predicted as suitable to the establishment of the mosquito in the future, including in
northern Europe, and no decrease in suitability is expected. These results show the
importance of planning for vector surveillance and control, even in areas where the risk
of establishment of Ae. albopictus is currently low.N/
Macroclimate Determines the Global Range Limit of Aedes aegypti
Aedes aegypti is the main vector of dengue and a number of other diseases worldwide. Because of the domestic nature of this mosquito, the relative importance of macroclimate in shaping its distribution has been a controversial issue. We have captured here the worldwide macroclimatic conditions occupied by A. aegypti in the last century. We assessed the ability of this information to predict the species' observed distribution using supra-continental spatially-uncorrelated data. We further projected the distribution of the colonized climates in the near future (2010-2039) under two climate-change scenarios. Our results indicate that the macroclimate is largely responsible for setting the maximum range limit of A. aegypti worldwide and that in the near future, relatively wide areas beyond this limit will receive macroclimates previously occupied by the species. By comparing our projections, with those from a previous model based strictly on species-climate relationships (i.e., excluding human influence), we also found support for the hypothesis that much of the species' range in temperate and subtropical regions is being sustained by artificial environments. Altogether, these findings suggest that, if the domestic environments commonly exploited by this species are available in the newly suitable areas, its distribution may expand considerably in the near future.info:eu-repo/semantics/publishedVersio
O mosquito vector da malária anopheles atroparvus, van thiel, 1927: adequabilidade de habitat em Portugal continental e potenciais alterações futuras do seu espaço climático
Tese de mestrado, Geografia, Universidade de Lisboa, Faculdade de Letras, 2009A malária constituiu-se como um dos principais problemas de saúde na primeira metade do séc. XX em Portugal. Actualmente, pese embora não se registem casos endémicos, a ocorrência constante de casos importados associados uma possível capacidade de transmissão dos seus agentes infecciosos por Anopheles atroparvus, mantém presente a possibilidade de futuras infecções endémicas. Neste sentido procedeu-se à obtenção de modelos de distribuição potencial desta espécie vectora para Portugal Continental. Com base em vários levantamentos de campo referentes à presença de espécies do complexo Anopheles maculipennis e diversos factores ambientais considerados influentes na sua distribuição, foram utilizados três métodos correlativos distintos. A distribuição obtida identificou uma elevada adequabilidade da maioria do país a esta espécie, especialmente nas áreas meridionais e de interior. Identificou-se também uma constância entre a forma de distribuição da espécie aquando da endemicidade da doença e a sua distribuição actual. Também a influência das alterações climáticas é tida como responsável por alterações na forma de distribuição de espécies vectoras de malária. Com base neste pressuposto uma segunda parte deste trabalho remeteu-se à análise de eventuais influências destas alterações na área de distribuição de Anopheles atroparvus, correspondente na sua generalidade ao continente Europeu. Para isso foi efectuada a calibração de dois modelos com a distribuição actual da espécie tendo-se aplicado os parâmetros obtidos a variáveis representativas de cenários climáticos futuros. Os modelos alcançados permitiram identificar a chegada de conjugações climáticas distintas das verificadas no actual nicho da espécie em diversas áreas da sua distribuição actual, nomeadamente na Península Ibérica. Verificou-se ainda, para a totalidade dos cenários climáticos futuros uma subida em latitude das áreas de maior adequabilidade. Estas duas situações podem implicar futuras alterações na forma de distribuição e abundância da espécie, assim como de outras, suas competidoras, ou sujeitas alterações no seu próprio espaço climático.Malaria was one of the main health problems in the first half of the 20th Century in Mainland Portugal. Nowadays, although the disease is no longer endemic, the continuous occurrence of imported cases and the possibility of its transmission by Anopheles atroparvus, presently maintain the risk of future endemic infections. In this sense habitat suitability models for this species were made for Mainland Portugal. Using presence-absence data regarding Anopheles maculipennis species complex and various environmental factors considered influential in their distribution, three distinct correlative models were calibrated. The achieved distribution identified high suitability values for the majority of the country, especially southern and interior areas. It was also identified that habitat suitability for Anopheles atroparvus in the country remains very similar to the one existing about seven decades ago when malaria was endemic. Also the influence of climate change is regarded as responsible for changes in the distribution of disease vectors. Based on this assumption a second part of this work referred to the analysis of possible influences of these changes in the global distribution of Anopheles artoparvus which corresponds coarsely to the European continent. To do so two correlative models were calibrated with the species actual distribution, the achieved parameters were then applied to a set of climate variables representing several future climate scenarios obtained from a General Circulation Model. The obtained results showed that several areas of the species current distribution, namely parts of the Iberian Peninsula, will present climate conditions distinct from the ones found nowadays in its realized niche. These results also showed a shift of suitability to northern areas. These two situations may imply future changes in the distribution and abundance of Anopheles atroparvus, as well as other species, due to changes in their biotic interactions, or in their own climate envelop
Urban population in Europe is increasingly exposed to vector-borne diseases transmitted by the Asian-Tiger mosquito
The Asian Tiger mosquito (Aedes albopictus) entered in Europe through Albania around 40
years ago and, since then, has spread to nearly 30 European countries. In a context of global
and climatic changes, it is expected that the environmental suitability for the mosquito will
further expand in the future, therefore increasing the probability of disease outbreaks. Urban
areas are particularly vulnerable to the spread of vector-borne diseases, because they offer a
high number of potential hosts and have a strong interconnection amongst different areas and
neighbourhoods, fostered by available urban mobility options.
We analysed how much of the urban population in Europe might be exposed to vector-borne
diseases transmitted by the Asian-tiger mosquito, focusing on 65 metropolitan areas and other
large cities retrieved from the Urban Audit 2018 (EUROSTAT, 2018). In a first step, we
evaluated the environmental suitability of each urban area to the establishment of the species,
classifying the level of agreement between published predictions of its distribution. We
assumed a high level of certainty on suitability (or unsuitability) if at least 70% of the models
agreed, and a high uncertainty otherwise. We aggregated the consensus levels in three
categories (suitable, uncertain, unsuitable) and retrieved the corresponding level for each
urban area assuming the predominant category within its boundaries. The analysis was
performed for two timeframes, regarding present-day and future climatic conditions. Urban
population estimates for current (2020) and future (2050) conditions were obtained from the
Global Population Grid at 1-km2 resolution based on SSP3 (Shared Socioeconomic Pathway), a
scenario of societal development that considers an intermediate level of growth regarding
demographics, economics, technology and governance, among other features ().
Results show that, currently, 51% of the studied urban areas are already suitable to the
establishment of the species, mainly located in southern and central Europe and where 60
million people live. Indeed, outbreaks of dengue and chikungunya viruses transmitted by this
species have already occurred in Europe since 2010, for example in France, Italy and Croatia.
Conversely, 12% of the urban areas are currently unsuitable to the species, and these are
mainly located in Scandinavia, the Baltic countries and Poland. In the future, half of these cities
will become suitable with high certainty to the presence of the Asian-tiger mosquito, with over
4 million people exposed. By 2050, none of the urban areas will be unsuitable and over 80%
will have suitable environmental conditions for the species, including cities like Zurich, Prague,
London or Copenhagen. This means that the number of people potentially exposed is
estimated to increase to about 110 million. These findings point to the need of adapting public
health policies and implementing strategies to prevent the spread of vector-borne diseases in
European urban areas.N/
Assessing the current and future suitability to the Asian Tiger mosquito, a dengue and Zika vector, in major cities in Europe
The Asian Tiger mosquito is already established in many countries in Europe and cities are
particularly vulnerable to the spread of vector-borne diseases. We evaluated the suitability of
62 large urban areas in Europe to the establishment of the mosquito, based on the level of
agreement between published modelling results that estimated the spatial distribution of the
Aedes albopictus. We classified suitability and uncertainty levels according to the number of
matching models on a 25 km cell basis and retrieved the predominant class within the
boundaries of each urban area. We analysed 7 models for current conditions and 5 for future
conditions (2050-2080), as well as changes in classes between these two timeframes.
Currently, 60% of the cities are suitable to the mosquito, 8% are unsuitable and 32% show
high uncertainty. In the future, 87% will be suitable and none will be unsuitable, including
cities in the British Isles and Scandinavia, which will have to adapt their public health policies.info:eu-repo/semantics/publishedVersio
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