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Arjun Srivathsa Sushma Sharma Priya Singh Girish A. Punjabi Madan K. Oli 《Mammal Review》2020,50(4):399-412
- Large carnivores face high extinction risks, often exacerbated by the absence of adequate information on their ecological requirements, and the high economic and socio-political commitments that their conservation warrants. Country-scale conservation plans can serve as effective frameworks to prioritise areas, actions, and conservation investments.
- We explore conservation tenets of retention, recovery, and restoration for the Endangered dhole Cuon alpinus in India – a global stronghold for the species. Specifically, we: 1) examine the current status of dholes in India’s states using a recent distribution assessment; 2) identify areas for directing management interventions – zones to be targeted for population recovery and for habitat recovery; 3) identify potential areas for range expansion; 4) use eco-socio-political criteria to determine state-wise conservation priority scores and likelihood of conservation action; and 5) conduct an exhaustive review of all published literature on dholes.
- Dholes occupy ~49% of potential habitats in 685 of mainland India’s 2342 sub-districts. We identified 143 sub-districts with potential for dhole population recovery, 145 for habitat recovery, and 404 for range expansion. Of the 34 mainland states/union territories, 17 were identified as high priority for dhole conservation. Of these, nine are adequately equipped to implement management actions to conserve dholes, while eight need to improve capacity towards increasing likelihood of conservation success.
- Literature on dholes (from 1874 to 2019; n=237) was dominated by natural history notes, followed by distribution records and studies of population ecology. A majority of the reviewed studies were from India (55% of 215 country-specific papers). The number of studies showed an exponential increase over time: 43% were published in the last decade.
- Our review of published literature revealed significant knowledge gaps in terms of quantitative ecological assessments across all dhole range-countries. Given this context, our results provide a comprehensive, multi-dimensional, and administratively feasible road map for dhole conservation in India, with potential applicability in other dhole range-countries and also for other threatened species.
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Shaenandhoa GARCÍA‐RANGEL 《Mammal Review》2012,42(2):85-119
- 1 A wealth of information has been generated for the Andean bear Tremarctos ornatus during the past four decades, and a thorough review of the species' natural history, ecology and conservation is provided here.
- 2 The Andean bear is the only remaining bear species in South America. Evolutionarily, it is the youngest of all ursids and the only remnant taxon within the subfamily Tremarctinae. The species is distributed throughout the Andes mountain range from Venezuela to Bolivia, but the limits of its current and past range are uncertain.
- 3 The species is polyestrous, capable of delayed implantation and a facultative seasonal breeder. Genetic information is scarce, and species‐specific markers need to be developed for a more appropriate assessment of the genetic structure of wild populations.
- 4 Andean bears inhabit a wide variety of habitats across the Andes including different forest types and high‐elevation grasslands. They are omnivorous with a frugivorous/folivorous emphasis that is reflected by adaptations of the typical tremarctine mandible.
- 5 Andean bears are vulnerable to extinction due to land conversion and poaching. Efforts have been made to protect them, but threats have not been reduced significantly. Therefore, the species is expected to move faster towards extinction than any other carnivore in the region.
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- 1 Chemical communication in mammals includes an array of specific behaviours that are often ignored in terms of their potential relevance to conservation. Often used during territorial or social interactions between animals, chemical communication can also be used as a tool in reintroduction programmes. Reintroductions still exhibit high failure rates and methods to improve success should be investigated. The Eurasian beaver Castor fiber has been widely reintroduced across Europe after its near extinction in the 19th century.
- 2 Using olfactory studies in the beaver, we aim to demonstrate how scent transfers a range of information about the sender which can be used to monitor social and territorial behaviour along with general well‐being. Scent manipulation can be used to reduce human–beaver conflicts, and aid reintroduction success through reducing stress and territorial conflicts, and by influencing dispersal and settlement.
- 3 Two species of beavers, the Eurasian beaver and the North American beaver Castor canadensis, occupy freshwater habitats throughout North America and in parts of South America, most of Europe and parts of Asia. Most of the reviewed literature concerns the wild Eurasian beaver, its chemical communication and conservation; however, captive studies and those addressing North American beavers are also included.
- 4 Chemical communication is advanced and has been well documented in this highly territorial species. However, few studies directly link olfaction with conservation practices.
- 5 Olfactory studies in beavers can provide non‐invasive methods to monitor translocated animals and indicators of health. We conclude that chemical analysis, olfactory studies and behavioural manipulations involving semiochemicals have important impacts on conservation and can generate practical solutions to conservation problems including aiding animal capture, captive stress reduction, breeding pair formation and release site fidelity.
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Nathan F. Williams Louise McRae Robin Freeman Pol Capdevila Christopher F. Clements 《Ecology and evolution》2021,11(11):7069
- Mutual reinforcement between abiotic and biotic factors can drive small populations into a catastrophic downward spiral to extinction—a process known as the “extinction vortex.” However, empirical studies investigating extinction dynamics in relation to species'' traits have been lacking.
- We assembled a database of 35 vertebrate populations monitored to extirpation over a period of at least ten years, represented by 32 different species, including 25 birds, five mammals, and two reptiles. We supplemented these population time series with species‐specific mean adult body size to investigate whether this key intrinsic trait affects the dynamics of populations declining toward extinction.
- We performed three analyses to quantify the effects of adult body size on three characteristics of population dynamics: time to extinction, population growth rate, and residual variability in population growth rate.
- Our results provide support for the existence of extinction vortex dynamics in extirpated populations. We show that populations typically decline nonlinearly to extinction, while both the rate of population decline and variability in population growth rate increase as extinction is approached. Our results also suggest that smaller‐bodied species are particularly prone to the extinction vortex, with larger increases in rates of population decline and population growth rate variability when compared to larger‐bodied species.
- Our results reaffirm and extend our understanding of extinction dynamics in real‐life extirpated populations. In particular, we suggest that smaller‐bodied species may be at greater risk of rapid collapse to extinction than larger‐bodied species, and thus, management of smaller‐bodied species should focus on maintaining higher population abundances as a priority.
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Larissa Rosa de OLIVEIRA Rocio LOIZAGA DE CASTRO Susana CÁRDENAS‐ALAYZA Sandro Luis BONATTO 《Mammal Review》2012,42(4):275-303
- 1 Most aquatic mammals have high dispersal potential, and there are often severe conservation concerns related to their legal or illegal harvesting. Therefore, economic, social and forensic factors often arise in decisions relating to their population management. Molecular markers are essential tools in modern conservation genetics, revealing previously unknown aspects of aquatic mammal behaviour, natural history, population structure and demography. Molecular markers also have been used to define management units, to recognize taxonomic units, to conduct forensic analyses and to control illegal wildlife trade, providing valuable information for decision‐making in wildlife conservation and management.
- 2 We review studies published in peer‐reviewed journals between 1993 and 2010, in which genetic approaches have been applied to conservation‐related issues involving natural populations of 25 species of aquatic mammals in South America. These studies cover just 34% of the 70 aquatic mammal species recorded in South America.
- 3 Most of the studies are related to population structure, phylogeography, gene flow and dispersal movements. In addition, recent findings relate to evolutionarily significant units, management units, forensics and conservation policy.
- 4 Finally, we look to the future and, based on numbers of studies and conservation concerns, suggest which species, geographic areas and genetic studies should be prioritized. Moreover, we discuss constraints on research and suggest collaborative works that would provide critical information towards the effective conservation and management of aquatic mammals in South America.
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- South Africa is a megadiverse country. Here, natural communities are unevenly distributed across, and within, seven distinct biomes. In such heterogeneous landscapes, understanding spatial patterns of biodiversity is essential for planning and implementing efficient conservation measures.
- The southern Kalahari, forming part of South Africa's savanna biome, is an arid region of peculiarly high diversity and endemism. The responses of orthopteran assemblages to changing environmental conditions across the Kalahari were investigated by comparing alpha and beta diversity levels across discrete vegetation types in the Tswalu Kalahari Reserve. The degree of association between species and specific vegetation types were also studied and how a key life history trait - dispersal ability – influences community composition was determined.
- This study identified 46 grasshopper species within the reserve, which compares well with richness levels in other more productive habitats of the country. Local (alpha) diversity was higher in mountain and mountain-ecotone sites versus vegetation types on the plains, and species turnover was also exceptionally high – approaching 100% - across these two groups. The few (3) dispersal limited species recovered were associated only with the mountain-ecotone group, with emergent dominance patterns suggesting that competitive rather than dispersal abilities determine the species composition of unique assemblages in the landscape.
- Topology plays a key role in maintaining spatial diversity across the southern Kalahari landscape. Mountains, and their ecotones, promote not only species turnover, but also richness and functional diversity. These can be viewed as islands of diversity, and should be targeted priority areas for conservation beyond the boundaries of protected areas.
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Anine Jamin Markus Peintinger Urs Gimmi Rolf Holderegger Ariel Bergamini 《Ecology and evolution》2020,10(3):1264-1277
- Habitat loss leading to smaller patch sizes and decreasing connectivity is a major threat to global biodiversity. While some species vanish immediately after a change in habitat conditions, others show delayed extinction, that is, an extinction debt. In case of an extinction debt, the current species richness is higher than expected under present habitat conditions.
- We investigated wetlands of the canton of Zürich in the lowlands of Eastern Switzerland where a wetland loss of 90% over the last 150 years occurred. We related current species richness to current and past patch area and connectivity (in 1850, 1900, 1950, and 2000). We compared current with predicted species richness in wetlands with a substantial loss in patch area based on the species‐area relationship of wetlands without substantial loss in patch area and studied relationships between the richness of different species groups and current and historical area and connectivity of wetland patches.
- We found evidence of a possible extinction debt for long‐lived wetland specialist vascular plants: in wetlands, which substantially lost patch area, current species richness of long‐lived specialist vascular plants was higher than would have been expected based on current patch area. Additionally and besides current wetland area, historical area also explained current species richness of these species in a substantial and significant way. No evidence for an extinction debt in bryophytes was found.
- The possible unpaid extinction debt in the wetlands of the canton of Zürich is an appeal to nature conservation, which has the possibility to prevent likely future extinctions of species through specific conservation measures. In particular, a further reduction in wetlands must be prevented and restoration measures must be taken to increase the number of wetlands.
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Sean Tomlinson Wolfgang Lewandrowski Carole P. Elliott Ben P. Miller Shane R. Turner 《Ecology and evolution》2020,10(2):763-777
- Short‐range endemic plants often have edaphic specializations that, with their restricted distributions, expose them to increased risk of anthropogenic extinction.
- Here, we present a modeling approach to understand habitat suitability for Ricinocarpos brevis R.J.F.Hend. & Mollemans (Euphorbiaceae), a threatened shrub confined to three isolated populations in the semi‐arid south‐west of Western Australia. The model is a maximum entropy species distribution projection constructed on the basis of physical soil characteristics and geomorphology data at approximately 25 m2 (1 arc‐second) resolution.
- The model predicts the species to occur on shallow, low bulk density soils that are located high in the landscape. The model shows high affinity (72.1% average likelihood of occurrence) for the known populations of R. brevis, as well as identifying likely locations that are not currently known to support the species. There was a strong relationship between the likelihood of R. brevis occurrence and soil moisture content that the model estimated at a depth of 20 cm.
- We advocate that our approach should be standardized using publicly available data to generate testable hypotheses for the distribution and conservation management of short‐range endemic plant species for all of continental Australia.
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- 1 Changes in otter Lutra lutra distribution in Italy were examined by analysing geographical, historical and survey data.
- 2 As in other European countries, otters declined sharply in Italy during the late 1970s and throughout the 1980s. Between 1985 and 2004 the species became extinct, except for some reintroductions, in northern and most of central Italy while the species appears to have substantially recovered in its southern range. This recovery of the otter population is apparently not due to increased research effort, but reflects a real expansion of range.
- 3 Differences in the degree of range reduction during the second half of the 20th century and in the availability of suitable habitats are probably the major factors that have determined the two opposite trends shown by otter populations in the last 20 years.
- 4 Better knowledge of otter status and distribution is needed for effective conservation management. We suggest that a national survey of the Italian otter population that employs genetic approaches should represent a first step of the national action plan for otter conservation.
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