High Probability Of Extinction Research Articles

Fine-scale drivers of extinction risk: tadpole occupancy dynamics of the Table Mountain Ghost Frog (Heleophryne rosei)

Over the last four decades much progress has been made towards recognising causes of global amphibian declines, but knowledge of fine scale drivers, particularly for specialised species, remains poor, inhibiting conservation effectiveness. The case of the Table Mountain Ghost frog (Heleophryne rosei) provides an example of this, listed as Critically Endangered for the last 15 years with limited conservation actions identified due to a lack of information about threat mechanisms and magnitude of declines. To address this, we investigated H. rosei tadpole occupancy dynamics over three years in stream pools on Table Mountain in Cape Town, South Africa, the only locality where this species occurs. Tadpole spatiotemporal distribution was examined as a function of abiotic and biotic factors to quantify habitat requirements, rank threats, and identify conservation actions. Heleophryne rosei tadpole occupancy was negatively correlated with levels of fine sediments (silt and sand), which embed larger substrates and decrease the diversity of benthic microhabitat. Increased abundance of these fine sediments was also associated with higher extinction probabilities. Localised habitat degradation from hiking paths, alien vegetation, and flow manipulation were identified as the primary threats to this species, increasing the sources of fine sediments and inhibiting the fluvial systems ability to effectively flush these sediments out. Our results demonstrate the importance of pore space refugia for mountain headwater stream-adapted amphibians and provides the required data to inform management decisions for this Critically Endangered species.

The macroevolutionary dynamics of activity pattern in mammals: Primates in context

Activity pattern has played a prominent role in discussions of primate evolutionary history. Most primates are either diurnal or nocturnal, but a small number are active both diurnally and nocturnally. This pattern—cathemerality—also occurs at low frequency across mammals. Using a large sample of mammalian species, this study evaluates two macroevolutionary hypotheses proposed to explain why cathemerality is less common than diurnality and nocturnality: 1) that cathemeral lineages have higher extinction probabilities (differential diversification) and 2) that transitions out of cathemerality are more frequent, making it a less persistent state (differential state persistence). Rates of speciation, extinction, and transition between character states were estimated using hidden-rates models applied to a phylogenetic tree containing 3013 mammals classified by activity pattern. The models failed to detect consistent differences in diversification dynamics among activity patterns, but there is strong support for differential state persistence. Transition rates out of cathemerality tend to be much higher than transition rates out of nocturnality. Transition rates out of diurnality are similar to those for cathemerality in most clades, with two important exceptions: diurnality is unusually persistent in anthropoid primates and sciurid rodents. These two groups combine very low rates of transition out of diurnality with high speciation rates. This combination has no parallels among cathemeral lineages, explaining why diurnality has become more common than cathemerality in mammals. Similarly, the combination of rates found in anthropoids is sufficient to explain the low relative frequency of cathemerality in primates, making it unnecessary to appeal to high extinction probabilities in cathemeral lineages in this clade. These findings support the hypothesis that the distribution of activity patterns across mammals has been influenced primarily by differential state persistence, whereas the effect of differential diversification appears to have been more idiosyncratic.

Life-history of the Caucasian dwarf goby Knipowitschia caucasica in an Iranian coastal wetland of the southern Caspian Sea

The Caucasian dwarf goby Knipowitschia caucasica is a small fish in the coastal wetlands of the southern Caspian Sea. The objective of this work was to describe its life-history aspects from individuals collected in the Gomishan wetland of Iran, a highly degraded ecosystem. We collected 707 fish along 18 months and calculated a short life span, TL∞=47.25mm for males, and TL∞=43.05mm for females, high mortality rate (1.84 and 5.83 year-1 for males and females, respectively), female dominance (M: F as 1: 1.22), low fecundity (average absolute fecundity: 672 oocytes.female-1 and mean relative fecundity 1209 oocyte.g-1 ), comparatively large oocytes (0.593 mm, ranging from 0.220 to 0.924 mm) and dependence on the wetland for spawning. Given adverse environmental changes in wetlands, we support the hypothesis that life-history traits confer this fish a high probability of extinction.

Dynamic Occupancy of Wild Asian Elephant: A Case Study Based On the SMART Database from the Western Forest Complex in Thailand

Understanding distribution patterns is essential for the long-term conservation of megafauna, particularly the Asian elephant (Elephas maximus). We investigated the dynamic occupancy of Asian elephants in the Thung Yai Naresuan West Wildlife Sanctuary in Thailand. Asian elephant occurrences were recorded during patrol activities from 2012 to 2019. We applied a single-species dynamic occupancy model to examine the environmental factors influencing habitat occupancy of Asian elephant across multiple seasons. The best-supported model, based on the Akaike information criterion (AIC), indicated that the normalized difference vegetation index and elevation positively influenced the probability of colonization. In contrast, the distance to the nearest population source sites showed a negative association. The probability of local extinction was positively correlated with the distance to the nearest villages and population source sites. The predictive map indicated a higher probability of colonization in a remote mountainous region of the center of the protected area. Higher extinction probability was associated with areas of dense human activity and far from population source sites connecting the Asian elephant population to the east. This is the first study to utilize a patrol database for assessing the dynamic occupancy of Asian elephants across multiple years. Our model provides insight into the dynamic distribution patterns of Asian elephants within the wildlife sanctuary and the factors that most influence these patterns. Long-term ecological data provide crucial information for assessing biodiversity, population status, and the ecological processes of focal wildlife species and are valuable for both protected area management and conservation efforts.

A Comparison of Deterministic and Stochastic Plant-Vector-Virus Models Based on Probability of Disease Extinction and Outbreak

In this investigation, we formulate and analyse a stochastic epidemic model using the continuous-time Markov chain model for the propagation of a vector-borne cassava mosaic disease in a single population. The stochastic model is based upon a pre-existing deterministic plant-vector-virus model. To see how demographic stochasticity affects the vector-borne cassava mosaic disease dynamics, we compare the disease dynamics of both deterministic and stochastic models through disease extinction process. The probability of disease extinction and therefore the major outbreak are estimated analytically using the multitype Galton-Watson branching process (GWbp) approximation. Also, we have found the approximate probabilities of disease extinction numerically based on 30000 sample paths, and it is shown to be good estimate with the calculated probabilities from GWbp approximation. In particular, it is observed that there is a very high probability of disease extinction when the disease is introduced via the infected vectors rather than through infected plants.

Complex demographic responses to contrasting climate drivers lead to divergent population trends across the range of a threatened alpine plant

Alpine plants are likely to be particularly vulnerable to climate change because of their restricted distributions and sensitivity to rapid environmental shifts occurring in high-elevation ecosystems. The well-studied Haleakalā silversword (‘āhinahina, Argyroxiphium sandwicense subsp. macrocephalum ) already exhibits substantial climate-associated population decline, and offers the opportunity to understand the ecological and demographic mechanisms that underlie ongoing and predicted range shifts. We use nearly four decades of demographic monitoring for this threatened Hawaiian species, in combination with other biological, ecological and climate data to explore demographic responses across its entire range. We construct and independently validate population models for two elevation zones representing the species’ lower trailing and higher stable regions. Differences in population growth rate (lambda) between trailing and stable regions were influenced most strongly by lower survival of juvenile and small adult size classes, as well as by lower recruitment and lower survival of seedlings and large adults in the trailing region. Furthermore, seed production appears to have decreased from the 1980’s to present in the trailing region, and is now significantly less than in the stable region. Lambda and several underlying vital rates were significantly associated with wetter dry season conditions in the lower trailing region, indicating water limitation. In the higher elevation stable region, in contrast, lambda and vital rates were associated with warmer air temperatures, indicating cold limitation. These contrasting demographic patterns and climate dependencies lead to a high probability of extinction over the next century in the lower region, where most plants occur, but zero probability of the same in the higher region, according to stochastic population projections. Drier future scenarios further increase the probability of extinction at low elevations. The combined results illustrate the complexity in the demographic response and future viability that can occur across the range of a single species.

Dolphin population specialized in foraging with artisanal fishers requires zero‐bycatch management to persist

Abstract The small population paradigm assumes that populations with low numbers of individuals intrinsically have a high probability of extinction. The small population of Lahille’s bottlenose dolphins Tursiops truncatus gephyreus that specializes in foraging with artisanal fishers in Laguna, southern Brazil, faces human pressures including bycatch in fishing gear. The viability of this population was modelled over 30 and 100 years under different levels of bycatch, including the current scenario of two bycatches every year, two scenarios with higher incidence of bycatches and three management scenarios. The sensitivity of predicted growth rates to fixed‐proportion and observed‐variation changes in life history parameters was explored. The current scenario predicted a declining population (r = −0.014; λ = 0.986) with a high probability of extinction in the long term (PE = 0.71). A small increase in bycatches would result in a marked increase in the probability of extinction. Management scenarios seem promising, but only the zero‐bycatch management scenario would make the difference between a declining and an increasing population. As expected for slow‐growing species, population growth rate was most sensitive to proportional changes in adult female and juvenile survival. However, considering observed variation in vital rates, population dynamics were most influenced by variation in reproductive rates. To determine the highest priority for management action, another simulation was made of how additional threat scenarios of recognized human activities (i.e. bycatch influencing adult survival and increased underwater noise or pollution influencing calf survival) would affect population dynamics. Population growth rate was very sensitive to changes in adult bycatch (especially females), as expected, and only subtly sensitive to a reduction in calf survival. The current level of bycatch is unsustainable. Bycatch needs to be eliminated to maximize the probability of long‐term persistence of this dolphin population. However, this population’s persistence could be threatened by natural variation in reproductive rates.

Ecological significance of entomofauna and main factors of loss of its biodiversity

Analysis of modern domestic and world scientific sources concerning ecological significance of the entomofauna of agroecosystems was presented and the main factors that cause the loss of species diversity of insects were identified in the article. Biodiversity loss, including entomofauna caused by anthropogenic activity and climate changes over the last 100 years is unprecedented in human history. More than 40% of insect species are extinct, and a third is endangered. According to more optimistic data, the total mass of insects decreases by 2.5% annually, that indicates a high probability of extinction within a century. Habitat degradation, agricultural intensification, climate change and invasive species were identified as major factors of the global loss of entomofauna biodiversity. Habitat degradation as a direct consequence of the expansion and intensification of agricultural production leads not only to the homogenization of ecosystems, but also to an increase in the use of pesticides and agrochemicals that have a negative impact on biodiversity and ecological state of the natural environment. Climate changes, in particular, rising temperatures, affect the life cycle of insects and their geographical distribution, and invasive species change the functioning of ecosystems, displacing local fauna. Climate changes can affect phytophagous insects in several ways: lead to expanding of their geographical distribution, increase winter survival, increase the number of generations, change the interaction between plants and pests, change interspecific interaction, increase the risk of invading migratory pests, increase in plant attack by pathogens passed by insects, reduction the efficiency of biological control, especially natural enemies.

A 150-year avian bio-inventory on a global biodiversity hotspot island

Knowledge of species inventory is crucial for identifying when and where species occur historically and geographically; yet few studies have gathered heterogeneous data from different sources to understand long-term spatio-temporal species dynamics in response to ongoing global environmental change. Hainan Island, China is a global biodiversity hotspot and an important transit station on the longest bird migratory flyway in the world. Here, we compiled a comprehensive database including 452 bird species recorded on Hainan Island. The records covered 150 years (1868–2017) and were sourced from published reports, museum specimens, field surveys, and citizen bird watching data. We showed that, since the first scientific report by Swinhoe (1869), the bird records on Hainan Island have increased with more intensive sampling efforts, wider survey areas, and more diverse investigation objectives. Overall, the birds recorded on Hainan Island were of the Oriental type, and the majority were tropical residents. Natural forests and coastal wetlands hosted the highest species richness, but some species were only recorded before 1910, indicating a high probability of species extinction owing to the loss of natural forest and wetland habitats. The spatial distribution of the birds showed a clear altitudinal pattern with more species below altitudes of 500 m. These species are not under effective protection because most of the protected areas are located between 500 and 1000 m. Our study provides a fundamental baseline dataset of the historical bird records on Hainan Island. We suggest that future conservation efforts on Hainan’s birds should target the tropical endemic species and those sensitive to climate change to maximise the preservation of avian biodiversity in China.

Genetic variation in resistance and high fecundity impede viral biocontrol of invasive fish

Abstract Common carp Cyprinus carpio is one of the top global invasive vertebrates and can cause significant ecological damage. The Australian Government's National Carp Control Program (NCCP) proposes to release Koi herpesvirus (KHV) to eradicate feral carp in one of the largest ecological interventions ever attempted. Ecological and human health risks have been highlighted regarding the release of a highly pathogenic viral biocontrol for an aquatic species. The efficacy of KHV has also been questioned, and it has not been demonstrated to produce lasting population reductions. We developed an individual‐based model (IBM) to examine the ecological and evolutionary response of a carp population after KHV release. This simulated the interaction between fish life history, viral epidemiology, host genetic resistance and population demography to critically evaluate the impact of KHV release under optimal conditions and a ‘best‐case scenario’ for disease transmission. KHV will rarely result in prolonged reductions or population extinctions. Crucially, realistic scenarios result in a rapidly rebounding population of resistant individuals. Additional measures aimed to reduce carp population recovery rate (e.g. with genetic engineering) require rapid efficacy to significantly reduce carp numbers alongside KHV. Fish fecundity has an overwhelming influence on viral efficacy as a biocontrol agent when combined with genetic resistance within a population. A high probability of population extinction is only met when carp fecundity is reduced to 1% of biological observations. Synthesis and applications. We use an individual‐based model to evaluate the efficacy of Koi herpesvirus biocontrol in Common Carp, and find that high host fecundity combined with genetic resistance results in rapid population rebound after initial large fish kills. Biocontrol approaches relying on natural selection lose efficacy over successive generations as resistance genes increase in frequency. Given the intense logistical effort and risks to ecosystems and human health associated with large fish kills after viral release, we suggest that sustained manual removal, alongside ecological restoration to favour recovery of native species, provides a risk‐free approach to reducing populations.

Probability of Disease Extinction or Outbreak in a Stochastic Epidemic Model for West Nile Virus Dynamics in Birds.

Thresholds for disease extinction provide essential information for the prevention and control of diseases. In this paper, a stochastic epidemic model, a continuous-time Markov chain, for the transmission dynamics of West Nile virus in birds is developed based on the assumptions of its analogous deterministic model. The branching process is applied to derive the extinction threshold for the stochastic model and conditions for disease extinction or persistence. The probability of disease extinction computed from the branching process is shown to be in good agreement with the probability approximated from numerical simulations. The disease dynamics of both models are compared to ascertain the effect of demographic stochasticity on West Nile virus dynamics. Analytical and numerical results show differences in model predictions and asymptotic dynamics between stochastic and deterministic models that are crucial for the prevention of disease outbreaks. It is found that there is a high probability of disease extinction if the disease emerges from exposed mosquitoes unlike if it emerges from infectious mosquitoes and birds. Finite-time to disease extinction is estimated using sample paths and it is shown that the epidemic duration is shortest if the disease is introduced by exposed mosquitoes.

Native trees in Nug-as forest Key Biodiversity Area, Cebu, Philippines

Abstract. Lillo EP, Malaki AB, Alcazar SMT, Redoblando BR, Diaz JLB, Pinote JP, Rosales R, Buot IE Jr. 2020. Native trees in Nug-as forest Key Biodiversity Area, Cebu, Philippines. Biodiversitas 21: 4162-4167. Threatened species, by definition, have a high probability of extinction, and so each of their populations significantly contributes to their survival. This paper presents a list of threatened Native trees in Nug-as forest of the Municipality of Alcoy, Cebu. A list of indicators was used to identify the conservation status of the Native trees at the local level. A total of 135 native trees from 48 families and 105 genera were recorded. Most species belong to the families of Euphorbiaceae, Lauraceae, Moraceae, Clusiaceae, Myrtaceae, Meliaceae, Fabaceae, and Rutaceae. In this study, 62 species were categorized as threatened, and 72 species as Least Concern, while in IUCN classification 19 threatened species were recorded, and 111 taxa considered as Least Concern respectively. Using the DENR method of classification 15 threatened species were recorded, and 115 taxa considered as Not Evaluated. The Nug-as forest was degraded by illegal cutting, kaingin, hunting and charcoal making. Based from Beynen and Townsend analysis, Nug-as forest was categorized as moderately disturbed. While DENR and IUCN declaration on the status of the Philippine native trees take a very long time, threatened plant species would be gone before we know it, considering the destruction rate in the Philippines.

Experimental warming induces oxidative stress and immunosuppression in a viviparous lizard, Eremias multiocellata.

Reptiles are especially vulnerable to climate warming because their behavior, physiology, and life history are highly dependent on environmental temperature. In this study, we envisaged new probable mechanisms underlying the high vulnerability of lizards, wherein heat exposure induces oxidative stress and leads to immunosuppression. To test this hypothesis, we conducted a warming experiment on a lizard (Eremias multiocellata) from a desert steppe in Inner Mongolia from May to September using open-top chambers set up in their natural habitat and compared the components of oxidative stress (antioxidant ability [Superoxide dismutase (SOD) activity], extent of oxidative damage [malondialdehyde (MDA) content]), and immunocompetence (white blood cells [WBC] counts and immunoglobulin M [IgM] expression) between the warming and control groups. At the end of the experiment, the warming treatment did not affect the survival rate of the lizards. However, MDA content, but not SOD activity, was significantly higher in the warming group than in the control group. The WBC counts and IgM expression were significantly lower in the warming group than in the control group. Our results verified our hypothesis and provided novel cues and methods for the investigation of the mechanisms behind the high probability of extinction of other ectotherms under warming conditions.

Lower levels of human disturbance correspond with longer-term persistence of Endangered Green Peafowl Pavo muticus populations

SummaryGalliformes are one of the most threatened groups of birds in South-East Asia, with 27% of the species threatened with extinction. Long term population viability and extinction probability studies, at different levels of threat and management, are lacking due to weak life history data. This study aimed to define the long-term viability and extinction risk of two populations of the endangered Green Peafowl Pavo muticus, facing different threat and protection levels, using Bayesian Population Viability Analysis (BPVA), which requires less data than traditional methods. The results showed an increasing trend in the Green Peafowl population in HuaiKhaKhaeng Wildlife Sanctuary (western Thailand), with a high protection level and low disturbance and high probability of assuring persistence for the next 100 years. By contrast, the population in YokDon National Park (south-central Vietnam), with a high habitat disturbance level and significant hunting pressure, is predicted to decline and has a high probability (99%) of extinction by 2097. Also, the BPVA showed minimum viable population (MVP) estimates of 250 and 450 calling males for the HuaiKhaKhaeng and YokDon populations respectively, assuring high probabilities of long-term persistence if the minimum numbers of males are available. The population size of 219 calling males at YokDon during the 2013 survey is lower than the MVP threshold of 450 calling males, which suggests the species has a low probability of long-term persistence in the area. Despite limited life history and population data, BPVA predicted the future of this population under site-specific conditions, and the results could be used to promote better management and population restoration.

An integrated population model sheds light on the complex population dynamics of a unique colonial breeder

AbstractClimate models forecast increasing climatic variation and more extreme events, which could increase the variability in animal demographic rates. More variable demographic rates generally lead to lower population growth and can be detrimental to wild populations, especially if the particular demographic rates affected are those to which population growth is most sensitive. We investigated the population dynamics of a metapopulation of 25 colonies of a semi‐arid bird species, the sociable weaver Philetairus socius, and how it was influenced by seasonal weather during 1993–2014. We constructed an integrated population model which estimated population sizes similar to observed population counts, and allowed us to estimate annual fecundity and recruitment. Variance in fecundity contributed most to variance in population growth, which showed no trend over time. No weather variables explained overall demographic variation at the population level. However, a separate analysis of the largest colony showed a clear decline with a high extinction probability (0.05 to 0.33) within 5 years after the study period. In this colony, juvenile survival was lower when summers were hot, and adult survival was lower when winters were cold. Rainfall was also negatively correlated with adult survival. These weather effects could be due to increased physiological demands of thermoregulation and rainfall‐induced breeding activity. Our results suggest that the dynamics of the population on the whole are buffered against current weather variation, as individual colonies apparently react in different ways. However, if more and increasingly extreme weather events synchronize colony dynamics, they are likely to have negative effects.

Viability of multiple populations across the range of a species at risk: The case of Pitcher's thistle, Cirsium pitcheri, in Canada

A quantitative, probabilistic approach to species and population assessment can be used to inform a species' legal at-risk designation and help determine priorities and targets for population recovery and protection measures. To that aim, we analysed the viability of a large number of individual populations of a species across its range in Canada, we compared that viability among populations, and we assess the viability of all those populations as a whole. We used Pitcher's thistle, Cirsium pitcheri, as a case because it is listed at risk in both Canada and the United States but its actual risk of extinction remains unclear. Also, for this monocarpic plant endemic to Great Lakes dunes and beaches, there are 35 years of monitoring data available for the populations in Pukaskwa National Park on Lake Superior, and nearly 17 years of data for populations on Lake Huron. Means and variances of the annual population growth rates were computed from those time series, to estimate the cumulative distribution function for time-to-extinction, using the diffusion approximation as well as simulations. We also ran multi-population stochastic projections to estimate the risk of decline of the whole Canadian population. We found that many Pitcher's thistle populations have a high probability of either extinction or undergoing a 50% decline at some point in their future. This is due mainly to steady declines experienced by small populations. However, multi-population stochastic projections and the projected growth of many large individual populations indicate that Pitcher's thistle is likely to persist in Canada over the next 100 years, assuming past conditions continue in the future.

Spatio-temporal analysis of floating islands and their behavioral changes in Loktak Lake with respect to biodiversity using remote sensing and GIS techniques.

The presence of floating islands is a unique characteristic of Loktak Lake. Floating islands play a significant role in ecosystem services and ecological processes and functioning. Rapid urbanization, industrialization, and a demand for more resources have led to changes in the landscape patterns at Loktak Lake in past three decades, thereby degrading and threatening the fragile ecosystem. The aim of the present study is to assess the changes in land use practices of the Phumdis by analyzing data from the past 38years with remote sensing techniques. Landsat images from 1977, 1988, 1999 and an Indian remote sensing image from 2015 were used to assess the land use/land cover changes. The methodology adopted is a supervised classification using the maximum likelihood technique in ERDAS software. Five land used classes were employed: open water bodies, agricultural areas, Phumdis with thick vegetation, and Phumdis with thin vegetation and settlements. The results indicate that the highest loss of land used class was in Phumdis with thin vegetation (49.38km2) followed by Phumdis with thick vegetation (8.59km2), while there was an overall increase in open water bodies (27.00km2), agricultural areas (25.33km2), and settlement (5.75km2). Our study highlights the loss of floating islands from the Loktak as a major concern that will lead to the destruction of the only "floating national park in the world." There is a high probability of extinction of the Sangai, an important keystone species found in the Indo-Burma biodiversity hotspot, if floating islands are not protected through sustainable development.

Clarifying the Range of the Endangered Largetooth Sawfish in the United States

The United States population of the endangered Largetooth Sawfish (Pristis pristis) has a high probability of extinction. It is critical to identify areas with valid historical records as these areas may be important to the recovery of the species. The U.S. range is reported to extend as far east as Florida based on one vouchered specimen and 3 historical records from this state. Three of these reports presume a local capture location despite a lack of locality data. The vouchered specimen was presumed captured in southern Florida, but evidence suggests otherwise. Dried specimens observed in Florida were most likely imported to Florida from the Indo—Pacific region, or from the Caribbean, for the marine curio trade. A vouchered rostrum, purportedly from Louisiana, lacks locality data and it cannot reliably be assigned to this state. We believe that the range of the Largetooth Sawfish in the U.S. never extended farther east than Texas, which was likely the northern limit of its range in the western Atlantic Ocean. Future conservation efforts should be directed to areas in Texas rather than states to the east where the species likely never occurred.

Extinction‐driven changes in frugivore communities on oceanic islands

Global change and human expansion have resulted in many species extinctions worldwide, but the geographic variation and determinants of extinction risk in particular guilds still remain little explored. Here, we quantified insular extinctions of frugivorous vertebrates (including birds, mammals and reptiles) across 74 tropical and subtropical oceanic islands within 20 archipelagos worldwide and investigated extinction in relation to island characteristics (island area, isolation, elevation and climate) and species’ functional traits (body mass, diet and ability to fly). Out of the 74 islands, 33 islands (45%) have records of frugivore extinctions, with one third (mean: 34%, range: 2–100%) of the pre‐extinction frugivore community being lost. Geographic areas with more than 50% loss of pre‐extinction species richness include islands in the Pacific (within Hawaii, Cook Islands and Tonga Islands) and the Indian Ocean (Mascarenes, Seychelles). The proportion of species richness lost from original pre‐extinction communities is highest on small and isolated islands, increases with island elevation, but is unrelated to temperature or precipitation. Large and flightless species had higher extinction probability than small or volant species. Across islands with extinction events, a pronounced downsizing of the frugivore community is observed, with a strong extinction‐driven reduction of mean body mass (mean: 37%, range: –18–100%) and maximum body mass (mean: 51%, range: 0–100%). The results document a substantial trophic downgrading of frugivore communities on oceanic islands worldwide, with a non‐random pattern in relation to geography, island characteristics and species’ functional traits. This implies severe consequences for ecosystem processes that depend on mutualistic plant–animal interactions, including ecosystem dynamics that result from the dispersal of large‐seeded plants by large‐bodied frugivores. We suggest that targeted conservation and rewilding efforts on islands are needed to halt the defaunation of large and non‐volant seed dispersers and to restore frugivore communities and key ecological interactions.

MaxEnt modeling for predicting suitable habitats and identifying the effects of climate change on a threatened species, Daphne mucronata, in central Iran

Climate changes pose serious challenges to the persistence of plant species, especially those with narrow habitats. Failure to adopt timely measures would lead to the permanent loss of valuable endangered species. This study used maximum entropy to predict the geographical distribution of a medicinal and vulnerable plant species, Daphne mucronata Royle, under current and future climatic conditions (A2a/HadCM3) in central Iran. A total of 100 locations with the species occurrence were recorded. Three topographic variables (slope, elevation, and aspect) and 19 bioclimatic variables derived from monthly data (spatial resolution=1km) were used in the modeling process. The results showed that D. mucronata distribution was largely affected by elevation, annual precipitation, and precipitation of coldest quarter. According to species response curves, this species preferred habitats with mean precipitation of coldest quarter from 120 to 140mm, annual precipitation of 240–280mm, and elevation more than 2600m above sea level. The climate change projection (A2a/HadCM3) indicated that by 2030 and 2080, D. mucronata would disappear in sites located below 2000m, remain unchanged in elevations more than 3000m, and undergo a drastic change in sites located at 2000–3000m above sea level. This information is essential for conservation planners and rangeland managers who work on protecting the species from extinction. A similar approach can be adopted to identify sites with high extinction probability of endangered species and to protect susceptible habitats from the effects of climate change and future modifications.