Correlative Distribution Models Research Articles

Vulnerability of global forest ecoregions to future climate change

The vulnerability of global forest ecoregions to future climate change represents a major threat to biodiversity and ecosystems worldwide. Therefore, it is important to investigate this vulnerability to improve the global conservation management network for biodiversity and ecosystems. We used species–area relationship coupled with correlative distribution modelling to conduct a global vulnerability assessment on 387 forest ecoregions under future climate change across different (1) biomes, (2) biogeographical realms and (3) conservation statuses. We found that 8.8% of global forest ecoregions were highly vulnerable in a low-greenhouse-gas-concentration scenario, and 32.6% of the global forest ecoregions were highly vulnerable in the high-greenhouse-gas-concentration scenario. Furthermore, the overall vulnerability of forest ecoregions was significantly greater for the high-rather than the low-greenhouse-gas-concentration scenario. In particular, critical or endangered forest ecoregions of Temperate Broadleaf and Mixed Forests, Temperate Conifer Forests, Tropical and Subtropical Dry Broadleaf Forests and Tropical and Subtropical Moist Broadleaf Forests were highly vulnerable in Nearctic, Neotropic and Palearctic realms. Furthermore, relatively stable and intact Tropical and Subtropical Moist Broadleaf Forests may be threatened in Neotropic and Afrotropic realms due to their climate change vulnerability. Hence, due to increasing greenhouse gas concentrations, future climate change must be incorporated into forest ecoregion conservation management to improve the effectiveness of global conservation network systems for biodiversity and ecosystems.

Spatiotemporal and molecular epidemiology of cutaneous leishmaniasis in Libya

BackgroundCutaneous leishmaniasis (CL) is a major public health problem in Libya. In this paper, we describe the eco-epidemiological parameters of CL during the armed conflict period from January 2011 till December 2012. Current spatiotemporal distributions of CL cases were explored and projected to the future using a correlative modelling approach. In addition the present results were compared with our previous data obtained for the time period 1995–2008.Methodology/Principal findingsWe investigated 312 CL patients who presented to the Dermatology Department at the Tripoli Central Hospital and came from 81 endemic areas distributed in 10 districts. The patients presented with typical localized lesions which appeared commonly on the face, arms and legs. Molecular identification of parasites by a PCR-RFLP approach targeting the ITS1 region of the rDNA was successful for 81 patients with two causative species identified: L. major and L. tropica comprised 59 (72.8%) and 22 (27.2%) cases, respectively. Around 77.3% of L. tropica CL and 57.7% of L. major CL caused single lesions. Five CL patients among our data set were seropositive for HIV. L. tropica was found mainly in three districts, Murqub (27.3%), Jabal al Gharbi (27.3%) and Misrata (13.7%) while L. major was found in two districts, in Jabal al Gharbi (61%) and Jafara (20.3%). Seasonal occurrence of CL cases showed that most cases (74.2%) admitted to the hospital between November and March, L. major cases from November till January (69.4%), and L. tropica cases mainly in January and February (41%). Two risk factors were identified for the two species; the presence of previously infected household members, and the presence of rodents and sandflies in patient’s neighborhoods. Spatiotemporal projections using correlative distribution models based on current case data and climatic conditions showed that coastal regions have a higher level of risk due to more favourable conditions for the transmitting vectors.ConclusionFuture projection of CL until 2060 showed a trend of increasing incidence of CL in the north-western part of Libya, a spread along the coastal region and a possible emergence of new endemics in the north-eastern districts of Libya. These results should be considered for control programs to prevent the emergence of new endemic areas taking also into consideration changes in socio-economical factors such as migration, conflicts, urbanization, land use and access to health care.

Projections of future habitat use by Atlantic bluefin tuna: mechanistic vs. correlative distribution models

Climate change is likely to drive complex shifts in the distribution and ecology of marine species. Projections of future changes may vary, however, depending on the biological impact model used. In this study, we compared a correlative species distribution model and a simple mechanistic oxygen balance model for Atlantic bluefin tuna (Thunnus thynnus: ABFT) in the North Atlantic Ocean. Both models gave similar results for the recent historical time period, and suggested that ABFT generally occupy favourable metabolic habitats. Projections from an earth system model showed largely temperature-induced reductions in ABFT habitat in the tropical and sub-tropical Atlantic by 2100. However, the oxygen balance model showed more optimistic results in parts of the subpolar North Atlantic. This was partially due to an inherent ability to extrapolate beyond conditions currently encountered by pelagic longline fishing fleets. Projections included considerable uncertainty due to the simplicity of the biological models, and the coarse spatiotemporal resolution of the analyses. Despite these limitations, our results suggest that climate change is likely to increase metabolic stress on ABFT in sub-tropical habitats, but may improve habitat suitability in subpolar habitats, with implications for spawning and migratory behaviours, and availability to fishing fleets.

Phylogeographic structure is strong in the Atlantic Forest; predictive power of correlative paleodistribution models, not always

We assess whether correlative paleoclimatic models of species ranges accurately predict genetic diversity patterns in species of distinct life histories traits in the Atlantic Forest (AF) of Brazil. To this end, we use sequences of the mitochondrial gene ND2 from Dendropsophus elegans and Chiasmocleis carvalhoi – summarized in the shape of phylogenies and population genetic statistics – and maximum entropy models of species distributions under current, 21 kya BP and 120 kya BP climatic reconstructions. The two target species have distinct ranges, habitat tolerances, rates of reproduction and dispersal abilities, yet are endemic to the AF. Although the more restricted and semi-fossorial C. carvalhoi is associated with forested habitats and thought to be a poor disperser, the widely ranged arboreal D. elegans inhabits open areas such as pastures and human-impacted regions of the AF, and is easily found perched on herbaceous vegetation in inundated areas. We had anticipated that correlative distribution models of the broadly distributed D. elegans would perform better then models of the narrowly ranged C. carvalhoi, thus better predicting current patterns of genetic diversity. The results demonstrate poor predictive ability of climate-based models of C. carvalhoi under current climatic conditions, suggesting that factors such as biotic interactions or dispersal ability may be playing a central role in defining this species distribution – both now and in the recent past. Models under current climate are nonetheless accurate in the broadly ranged D. elegans. As a corollary, paleoclimatic models accurately predicted patterns of diversity of the ND2 mitochondrial gene in D. elegans, but not in C. carvalhoi. We attribute these distinct responses to the poor explanatory power of paleodistributions models when applied to species that violate the basic assumption of the environment as main driver of distribution patterns. This calls for a careful use of distribution models for the purpose of evolutionary biogeographical inference. Like C. carvalhoi, other species whose ranges are not yet at equilibrium, or which are impacted by competitor, parasite or pathogen presence, may not be suitable to the combined use of paleoclimatic-model based phylogeographic inference, as here implemented – despite relatively high area under the curve values.

The role of climate, habitat, and species co‐occurrence as drivers of change in small mammal distributions over the past century

AbstractSpecies distribution models are commonly used to predict species responses to climate change. However, their usefulness in conservation planning and policy is controversial because they are difficult to validate across time and space. Here we capitalize on small mammal surveys repeated over a century in Yosemite National Park, USA, to assess accuracy of model predictions. Historical (1900–1940) climate, vegetation, and species occurrence data were used to develop single‐ and multi‐species multivariate adaptive regression spline distribution models for three species of chipmunk. Models were projected onto the current (1980–2007) environmental surface and then tested against modern field resurveys of each species. We evaluated models both within and between time periods and found that even with the inclusion of biotic predictors, climate alone is the dominant predictor explaining the distribution of the study species within a time period. However, climate was not consistently an adequate predictor of the distributional change observed in all three species across time. For two of the three species, climate alone or climate and vegetation models showed good predictive performance across time. The stability of the distribution from the past to present observed in the third species, however, was not predicted by our modeling approach. Our results demonstrate that correlative distribution models are useful in understanding species' potential responses to environmental change, but also show how changes in species‐environment correlations through time can limit the predictive performance of models.

SURVIVAL IN A CHANGING WORLD

![Figure][1] In August 2009, the International Union of Physiological Sciences (IUPS) held its 36th Congress in Kyoto in the same convention centre where the historic Kyoto Protocol was drawn up 12 years earlier. The symbolism of this coincidence was not missed by Malcolm Gordon, the Chair of

A mechanistic niche model for measuring species' distributional responses to seasonal temperature gradients.

Niche theory is central to understanding how species respond geographically to climate change. It defines a species' realized niche in a biological community, its fundamental niche as determined by physiology, and its potential niche—the fundamental niche in a given environment or geographic space. However, most predictions of the effects of climate change on species' distributions are limited to correlative models of the realized niche, which assume that species are in distributional equilibrium with respect to the variables or gradients included in the model. Here, I present a mechanistic niche model that measures species' responses to major seasonal temperature gradients that interact with the physiology of the organism. I then use lethal physiological temperatures to parameterize the model for bird species in North and South America and show that most focal bird species are not in direct physiological equilibrium with the gradients. Results also show that most focal bird species possess broad thermal tolerances encompassing novel climates that could become available with climate change. I conclude with discussion of how mechanistic niche models may be used to (i) gain insights into the processes that cause species to respond to climate change and (ii) build more accurate correlative distribution models in birds and other species.

An Australian Holocene climate reconstruction using Chironomidae from a tropical volcanic maar lake

Holocene sediments from Lake Barrine on the Atherton Tableland in tropical north-east Queensland, Australia (17°15′S, 145°38′E, 721 m asl) reveal 10 assemblage shifts in subfossil aquatic immature Chironomidae remains over the past 9000 years. Using the program CANOCO 3.12 and ordination analyses we examined relationships between the physico-chemistry of multiple local and regional water bodies and their chironomid fauna to assess the relative importance of various environmental and climatic parameters on the distribution of Australian chironomids. To derive palaeoclimates we used an extant assemblage to test reconstructions, over 50 calibrated radiocarbon dates from a 7.5-m sediment record, and the correlative distribution modelling programs DOMAIN and BIOCLIM to construct and overlap climate envelopes of species. In comparison with contemporary climate, reconstructed conditions were warmer annually by ∼2.5°C from 4650 calendar years before present (cal yr BP) to more recent times. Annual temperatures were slightly cooler between 5130 to 4650 cal yr BP and may have been cooler in the warmest quarter by ∼6.6°C between 6890 and 6090 cal yr BP. Precipitation estimates, although subject to greater errors, were reconstructed in the wettest quarter to be drier by around 500 mm at 5130–4650 and 6890–6090 cal yr BP. The inferred sensitivity of Chironomidae to climatic and environmental conditions at Lake Barrine suggests that Australian midges are reliable and informative biological indicators. Faunal changes were correlated with fluctuations in water levels, sediment influx, organic material, oxygen availability and nutrient status mediated by changes in the local climate and a shift from dry sclerophyll vegetation to rainforest within the catchment.