BackgroundRodents are recognized as hosts for at least 60 zoonotic diseases and may represent a serious threat for human health. In the context of global environmental changes and increasing mobility of humans and animals, contacts between pathogens and potential animal hosts and vectors are modified, amplifying the risk of disease emergence. An accurate identification of each rodent at a specific level is needed in order to understand their implications in the transmission of diseases. Among the Muridae, the Rattini tribe encompasses 167 species inhabiting South East Asia, a hotspot of both biodiversity and emerging and re-emerging diseases. The region faces growing economical development that affects habitats, biodiversity and health. Rat species have been demonstrated as significant hosts of pathogens but are still difficult to recognize at a specific level using morphological criteria. DNA-barcoding methods appear as accurate tools for rat species identification but their use is hampered by the need of reliable identification of reference specimens. In this study, we explore and highlight the limits of the current taxonomy of the Rattini tribe.ResultsWe used the DNA sequence information itself as the primary information source to establish group membership and estimate putative species boundaries. We sequenced two mitochondrial and one nuclear genes from 122 rat samples to perform phylogenetic reconstructions. The method of Pons and colleagues (2006) that determines, with no prior expectations, the locations of ancestral nodes defining putative species was then applied to our dataset. To give an appropriate name to each cluster recognized as a putative species, we reviewed information from the literature and obtained sequences from a museum holotype specimen following the ancient DNA criteria.ConclusionsUsing a recently developed methodology, this study succeeds in refining the taxonomy of one of the most difficult groups of mammals. Most of the species expected within the area were retrieved but new putative species limits were also indicated, in particular within Berylmys and Rattus genera, where future taxonomic studies should be directed. Our study lays the foundations to better investigate rodent-born diseases in South East Asia and illustrates the relevance of evolutionary studies for health and medical sciences.
Protected areas are often promoted as an important solution to preserving biodiversity. However, permeable edges can undermine the effectiveness of preserves because animals may move into adjacent human-dominated unprotected areas. We investigated attitudes toward, and sources of mortality of, a far-ranging apex predator, the king cobra (Ophiophagus hannah; Cantor 1836), in a biosphere reserve in northeastern Thailand. Our questionnaire revealed marked fear of snakes and hostility toward king cobras. Using radiotelemetry, we followed 23 king cobras over a 4-year period, during which time we documented the mortality of 14 individuals. We considered 10 of the deaths to be anthropogenic in origin, including road mortality, pollution, fish traps, and direct persecution; these deaths disproportionately occurred in unprotected areas. Our results highlight how dangerous human-dominated landscapes are for king cobras. Because king cobras move long distances and maintain large home ranges, it is likely that successful conservation of the species cannot be satisfactorily met by protected areas alone; a more holistic, education-focused conservation strategy is required. We stress the importance of a human dimensions approach that leads toward greater understanding of human attitudes toward king cobras, and snakes in general, combined with ecological research for more effective conservation.
13Studying animal movement provides insights into how animals react to land-use changes, specifically 14 how animals can change their behaviour in agricultural areas. Recent reviews show a tendency for 15 species to reduce movements in response to increased human landscape modification, but the study of 16 movement has not been extensively explored in reptiles. We examined movements of a large reptilian 17 predator, the King Cobra (Ophiophagus hannah), in Northeast Thailand. We used a consistent regime 18 of radio-telemetry tracking to document movements across protected forest and adjacent agricultural 19 areas. We then adapted GPS-targeting analytic methods to examine the movement using metrics of site 20 reuse and dynamic Brownian Bridge Movement Model derived motion variance. Examination of 21 motion variance demonstrated that King Cobra movements increased in forested areas and tended to 22 decrease in agricultural areas. Our Integrated Step-Selection Functions indicated that when moving in 23 agricultural areas King Cobras restricted their movements, thereby remaining within vegetated semi-24 natural areas, often located along the banks of irrigation canals. Site reuse metrics of residency time and 25 number of revisits remained unaffected by distance to landscape features. Neither motion variance nor 26 reuse metrics were consistently affected by the presence of threatening landscape features (e.g. roads, 27 human settlements); suggesting that King Cobras will remain in close proximity to threats, provided 28 habitat patches are available. Although King Cobras displayed heterogeneity in their response to 29 agricultural landscapes, the overall trend suggested a reduction in movements when faced with 30 fragmented habitat patches embedded in an otherwise inhospitable land-use matrix. Reductions in 31 movements are consistent with findings for mammals and forest specialist species. 32
This study aims to investigate the species diversity of rodents living in karst ecosystems of Thailand. A survey has been conducted throughout Thailand, 122 karsts sampled and 477 Murinae rodents live-trapped. Phylogenetic reconstructions were carried out using two mitochondrial markers (cytb, COI). A sequence-based species delimitation method completed by the analysis of the level of genetic divergence was then applied to define species boundaries within our dataset. The phylogenetic position of Niviventer hinpoon was also investigated and sequences obtained from the holotype specimen of this species were used to reliably identify samples of N. hinpoon. A total of 12 described Murinae species, corresponding to 17 deeply divergent genetic lineages, were encountered in limestone karsts of Thailand. Our study revealed an important genetic diversity within the traditionally recognized species Maxomys surifer (four highly divergent genetic lineages), Leopoldamys neilli (two highly divergent genetic lineages) and Berylmys bowersi (two highly divergent genetic lineages). These species could be considered as species complex and require further taxonomic work. This study also provides valuable information on the distribution of the two rodent species endemic to limestone karsts of Thailand, L. neilli and N. hinpoon. Leopoldamys neilli was the most abundant species encountered in Thai karsts during our survey. However, L. neilli specimens from western Thailand are genetically highly divergent from the remaining populations of L. neilli and could represent a separate species. Niviventer hinpoon, phylogenetically closely related to N. fulvescens, is much rarer and its distribution limited to central Thailand. Most of the other captured species are typically associated with forest ecosystems. This study suggests that limestone karsts play a key role in the preservation of the rodent species endemic to such habitat, but they would also provide refuges for the forest-dwelling Murinae rodents in deforested regions.
Background: Studying animal movement provides insights into how animals react to land-use changes. As agriculture expands, we can use animal movement to examine how animals change their behaviour in response. Recent reviews show a tendency for mammalian species to reduce movements in response to increased human landscape modification, but reptile movements have not been as extensively studied. Methods: We examined movements of a large reptilian predator, the King Cobra (Ophiophagus hannah), in Northeast Thailand. We used a consistent regime of radio telemetry tracking to document movements across protected forest and adjacent agricultural areas. Using dynamic Brownian Bridge Movement Model derived motion variance, Integrated Step-Selection Functions, and metrics of site reuse, we examined how King Cobra movements changed in agricultural areas. Results: Motion variance values indicated that King Cobra movements increased in forested areas and tended to decrease in agricultural areas. Our Integrated Step-Selection Functions revealed that when moving in agricultural areas King Cobras restricted their movements to remain within vegetated semi-natural areas, often located along the banks of irrigation canals. Site reuse metrics of residency time and number of revisits appeared unaffected by distance to landscape features (forests, semi-natural areas, settlements, water bodies, and roads). Neither motion variance nor reuse metrics were consistently affected by the presence of threatening landscape features (e.g. roads, human settlements), suggesting that King Cobras will remain in close proximity to threats, provided habitat patches are available. Conclusions: Although King Cobras displayed individual heterogeneity in their response to agricultural landscapes, the overall trend suggested reduced movements when faced with fragmented habitat patches embedded in an otherwise inhospitable land-use matrix. Movement reductions are consistent with findings for mammals and forest specialist species.
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