•Few practical guidelines exist on the best guidelines of ecological niche models.•We present a step by step guideline with best practices for correlative models.•We focus on data preparation; model ...calculation, evaluation, and model application.•This guideline will help to obtain better results when using correlative models.
The use of correlative ecological niche models has highly increased in the last decade. Despite all literature and textbooks in this field, few practical guidelines exist on the correct application of these techniques. We present here a step-by-step guideline explaining best practices for calculating correlative ecological niche models considering their conceptual and statistical assumptions and limitations. We divided the modelling process into four stages: 1) data collection and preparation; 2) model calculation; 3) model evaluation and validation; 4) and model application. Based on ecological niche theory, we review the concepts of ecological niche and how they can be modelled; classes of correlative models; modelling software; selection of study area; data sources for species records and environmental variables; types of species records and their influence on correlative models; errors in species records; minimum number of species records and environmental variables; effects of prevalence, sampling design, biases, and collinearity between variables; model calculation; model projection to different scenarios in time and space; ensemble modelling; model validation; classification, discrimination and calibration metrics; calculation of null models; analysis of model results; and model thresholding. This guideline is expected to help potential users to obtain better results when using correlative ecological niche models.
Aim
To understand spatial‐temporal changes (beta‐diversity) in coastal communities and their drivers in the context of climate change. Coastal ecosystems are extremely exposed and dynamic, where ...changes in seaweed assemblages have been associated with changing water temperatures. However, at local scale, the effects of changes in the upwelling events and related stressors seek further exploration.
Location
Galicia rías, North West of the Iberian Peninsula.
Methods
Using data collected in 42 sampling localities in Galicia rias and over two time periods (1998 and 2014), we analysed changes in the seaweed community's composition through time and space. We calculated the temporal beta‐diversity index and spatial beta‐diversity as the pairwise composition differences between sampling localities. We use generalized dissimilarity models, to identify local environmental drivers of spatial and temporal beta‐diversity.
Results
We found a significant change in seaweed communities of Galicia rias, between 1998 and 2014 (temporal beta‐diversity). They were mostly related to species loss rather than to species replacement. The dissimilarity among localities (spatial beta‐diversity) was significantly higher in 2014 than in 1998. Nitrate concentration was consistently predicted as the main driver of both temporal and spatial beta‐diversity patterns.
Main conclusions
Unlike other studies in marine ecosystems, our results suggest that observed changes in the structure of perennial seaweed assemblages in Galicia Rias might lead to a local biotic heterogenization, indirectly linked to climate change through changes in nutrients availability and the upwelling intensity. Changes in Galicia seaweed communities call scientific attention to the importance of local stressors in climate change studies.
Limpets (Patella spp.) are marine gastropods that inhabit rocky shores along the coasts of Europe, the Mediterranean, Macaronesia and the north-west coast of Africa. Being considered key species, ...limpets have an important role regulating algal assemblages in coastal communities. The goal of this work was to evaluate the influence of sea temperature on the respiration rate of four limpet species occurring in mainland Portugal, in line with predictions from the metabolic theory of ecology. The individuals were collected from rocky shores in Portugal and exposed to sea temperatures ranging from 6–28°C for respiration rate assessments. Following the estimation of the relationship between oxygen consumption and temperature the activation energy was calculated. In parallel, low and high thermal thresholds were determined for three of the species. The results indicated that P. ulyssiponensis oxygen consumption increased linearly with sea temperature and the remaining species presented the same tendency. The values of activation energy ranged between 0.33–0.76 eV. For P. ulyssiponensis, the highest activation energy indicated that this species is more sensitive to temperature variations while for the tested temperatures it presented a higher thermal tolerance limit than the other species. Such findings indicate that P. ulyssiponensis is the most susceptible of these species to climate change, in line with the tolerance–plasticity trade-off hypothesis. This work provides a good starting point for understanding the effect of sea temperature on oxygen consumption in Patella spp. and for comprehending sensitivity of limpets to temperature increases under future climate change scenarios.
Road-based citizen science surveys are increasingly used for long-term monitoring of wildlife, including amphibians, over large spatial scales. However, how representative such data are when compared ...to the actual species distribution remains unclear. Spatial biases in site selection or road network coverage by volunteers could skew results towards more urbanised areas and consequently produce incorrect or partial trend estimations at regional or national scales. Our objective was to compare and verify potential spatial biases of road-based data using distribution datasets of different origins. We used as a case study the common toad (
Bufo bufo
), a fast-declining species and the main amphibian targeted by conservation action on roads in Europe. We used Maxent models to compare road survey data obtained from the 35 year-long “Toads on Roads” project in Great Britain with models using national-scale toad distribution records as well as with models using randomly generated points on roads. Distribution models that used data collected by volunteers on roads produced similar results to those obtained from overall species distribution, indicating the lack of selection bias and high spatial coverage of volunteer-collected data on roads. Toads were generally absent from mountainous areas and, despite the high availability of potential recorders, showed nearly complete absence of road-based records in large urban areas. This is probably the first study that comparatively evaluates species distribution models created using datasets of different origin in order to verify the influence of potential spatial bias of data collected by volunteers on roads. Large-scale declines of widespread amphibians have been demonstrated using data collected on roads and our results indicate that such data are representative and certainly comparable to other existing datasets. We show that for countries with high road network coverage, such as Great Britain, road-based data collected by volunteers represent a robust dataset and a critical citizen science contribution to conservation.
Aim: Understanding the roles of allopatric fragmentation and niche divergence in intraspecific lineage diversification is central to our comprehension of how new species arise and evolve. Here we ...integrate an extensive multilocus dataset with species distribution models to address these topics in genetically differentiated population lineages of the common midwife toad (Alytes obstetricans). Location: Iberian Peninsula, Western Europe. Methods: We genotyped 965 individuals from 142 localities at 12 microsatellite loci to finely delineate the ranges of population lineages in A. obstetricans. We then built ecological niche-based models for each lineage and tested for niche overlap, equivalency and similarity based on PCA-env analyses. We also investigated the relationship between genetic and environmental distances across lineages. Results: We recovered seven differentiated genetic clusters, with mostly different (sometimes nonoverlapping) niches. However, niches are not more divergent than expected given the largely allopatric ranges of population lineages. We found no significant isolation by environment within lineages, with genetic distances mostly explained by geographical distances. Main conclusions: Allopatric fragmentation in A. obstetricans resulted in (sometimes highly) different niches in intraspecific population lineages. Within lineages, isolation by distance is the major driver of patterns of genetic variation. Our study highlights the importance of incorporating intraspecific genetic structure into species distribution models to explore spatial patterns of genetic diversity in terms of their underlying processes.
Climate change is eroding biodiversity and conservation efforts have focused on species’ potential responses to those changes. Biological traits associated with sensitivity and adaptive capacities ...may contribute in identifying a species vulnerability to climate change. Desert-living species could be particularly vulnerable to climate change as they may already live at their physiological limits. This work aims to identify functional groups in Sahara-Sahel endemics, to determine their spatial distribution and to evaluate how the predicted magnitude and velocity of climate change in the region might affect them. We collated biological traits data for all Sahara-Sahel endemics. We then summarized the functional strategy of each species into functional groups with different sensitivities and adaptive capacities to climate change. Future climate scenarios were reclassified to identify areas where predicted temperature and precipitation approach the physiological limits of each group. We calculated the velocity of temperature and precipitation change as the ratio of the temporal gradient to the spatial gradient. Specific magnitudes and velocities of environmental change threaten our seven function groups differently according to their level of exposure and geographical distributions. Groups are more exposed to precipitation than to temperature changes. The more exposed functional groups lived mostly in flat areas, where the predicted magnitude and velocities of change were also the highest. Some functional groups with high adaptive capacities (e.g. volant species) may be able to colonize distinct areas. Other groups with low sensitivity and adaptive capacity (e.g.: ectotherms with small home ranges) may be vulnerable to climate change. Different biological traits contributed to the extent to which climate change harms species. The desert-adapted species may be the most vulnerable ones. The vulnerability patterns of Sahara-Sahel functional groups provide indications of combinations of biological traits and biodiversity’s exposure to climate change in other warm deserts of the world.
The world is undergoing exceptional biodiversity loss. Most conservation efforts target biodiversity hotspots at large scales. Such approach overlooks small-sized local hotspots, which may be rich in ...endemic and highly threatened species. We explore the importance of mountain rock pools (gueltas) as local biodiversity hotspots in the Sahara-Sahel. Specifically, we considered how many vertebrates (total and endemics) use gueltas, what factors predict species richness, and which gueltas are of most priority for conservation. We expected to provide management recommendations, improve local biodiversity conservation, and simultaneously contribute with a framework for future enhancement of local communities' economy. The identification of local hotspots of biodiversity is important for revaluating global conservation priorities.
We quantified the number of vertebrate species from each taxonomic group and endemics present in 69 gueltas in Mauritania, then compared these with species present in a surrounding area and recorded in the country. We evaluated the predictors of species number's present in each guelta through a multiple regression model. We ranked gueltas by their priority for conservation taking into account the percentage of endemics and threats to each guelta. Within a mere aggregate extent of 43 ha, gueltas hold about 32% and 78% of the total taxa analysed and endemics of Mauritania, respectively. The number of species present in each guelta increased with the primary productivity and area of gueltas and occurrence of permanent water. Droughts and human activities threaten gueltas, while 64% of them are currently unprotected.
Gueltas are crucial for local biodiversity conservation and human activities. They require urgent management plans in Mauritania's mountains. They could provide refugia under climate change being important for long-term conservation of Sahara-Sahel biodiversity. Given their disproportional importance in relation to their size, they are local hotspots of biodiversity deserving global attention.
Mapping species' geographical distribution is fundamental for understanding current patterns and forecasting future changes. Living on rocky shores along the intertidal zone, limpets are vulnerable ...to climate change, as their range limits are controlled by seawater temperature. Many works have been studying limpets’ potential responses to climate change at local and regional scales. Focusing on four Patella species living on the rocky shores of the Portuguese continental coast, this study aims to predict climate change impacts on their global distribution, while exploring the role of the Portuguese intertidal as potential climate refugia.
Ecological niche models combine occurrences and environmental data to identify the drivers of these species' distributions, define their current range, and project to future climate scenarios. The distribution of these limpets was mostly defined by low bathymetry (intertidal) and the seawater temperature. Independent of the climate scenario, all species will gain suitable conditions at the northern distribution edge while losing in the south, yet only the extent of occurrence of P. rustica is expected to contract. Apart from the southern coast, maintenance of suitable conditions for these limpets’ occurrence was predicted for the western coast of Portugal. The predicted northward range shift follows the observed pattern observed for many intertidal species. Given the ecosystem role of this species, attention should be given to their southern range limits. Under the current upwelling effect, the Portuguese western coast might constitute thermal refugia for limpets in the future.
•Ecological niche models were used to predict limpets' distributions while projecting to future climate scenarios.•Seawater temperature is the major driver of limpets' global distribution.•Poleward shifts with possible northward expansion were predicted for the future.•The Portuguese western coast is probably a thermal refugium for limpets in the future.
Increasing conflicts and social insecurity are expected to accelerate biodiversity decline and escalate illegal wildlife killing. Sahara‐Sahel megafauna has experienced recent continuous decline due ...to unsustainable hunting pressure. Here, we provide the best available data on distribution and population trends of threatened, large vertebrates, to illustrate how escalating regional conflict (565% growth since 2011) is hastening population decline in areas that were formerly refugia for megafauna. Without conservation action, the unique and iconic biodiversity of Earth's largest desert will be forever lost. We recommend: (1) establishing strong commitments for change in global attitude toward nature; (2) engraining a culture of environmental responsibility among all stakeholders; (3) fostering environmental awareness to drive societal change; (4) reinforcing regional security and firearms control; and (5) implementing local research and wildlife monitoring schemes. We identify relevant international partners needed to tackle these challenges and to make strong policy change for biodiversity conservation and regional stability.
Detailed knowledge about biodiversity distribution is critical for monitoring the biological effects of global change processes. Biodiversity knowledge gaps hamper the monitoring of conservation ...trends and they are especially evident in the desert biome. Mauritania constitutes a remarkable example on how remoteness and regional insecurity affect current knowledge gaps. Mammals remain one of the least studied groups in this country, without a concerted species checklist, the mapping of regions concentrating mammal diversity, or a national assessment of their conservation status. This work assessed the diversity, distribution, and conservation of land mammals in Mauritania. A total of 6,718 published and original observations were assembled in a spatial database and used to update the occurrence status, distribution area, and conservation status. The updated taxonomic list comprises 107 species, including 93 extant, 12 Regionally Extinct, and 2 Extinct in the Wild. Mapping of species distributions allowed locating concentrations of extant mammal species richness in coastal areas, along the Senegal River valley, and in mountain plateaus. Recent regional extinction of large-sized Artiodactyla and Carnivora has been very high (11% extinct species). From the extant mammals, 11% are threatened, including flagship species (e.g., Addax nasomaculatus and Panthera pardus). Species richness is poorly represented by the current protected areas. Despite the strong advances made, 23% of species categorise as Data Deficient. Persisting systematics and distribution uncertainties require further research. Field surveys in currently unexplored areas (northern and south-eastern regions) are urgently needed to increase knowledge about threatened mammals. The long-term conservation of land mammals in Mauritania is embedded in a complex web of socioeconomic and environmental factors that call for collaborative action and investment in sustainable human development. The current work sets the baseline for the future development of detailed research studies and to address the general challenges faced by mammals and biodiversity in the country.
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