What factors influence the rediscovery of lost tetrapod species?

We created a database of lost and rediscovered tetrapod species, identified patterns in their distribution and factors influencing rediscovery. Tetrapod species are being lost at a faster rate than they are being rediscovered, due to slowing rates of rediscovery for amphibians, birds and mammals, and rapid rates of loss for reptiles. Finding lost species and preventing future losses should therefore be a conservation priority. By comparing the taxonomic and spatial distribution of lost and rediscovered tetrapod species, we have identified regions and taxa with many lost species in comparison to those that have been rediscovered-our results may help to prioritise search effort to find them. By identifying factors that influence rediscovery, we have improved our ability to broadly distinguish the types of species that are likely to be found from those that are not (because they are likely to be extinct). Some lost species, particularly those that are small and perceived to be uncharismatic, may have been neglected in terms of conservation effort, and other lost species may be hard to find due to their intrinsic characteristics and the characteristics of the environments they occupy (e.g. nocturnal species, fossorial species and species occupying habitats that are more difficult to survey such as wetlands). These lost species may genuinely await rediscovery. However, other lost species that possess characteristics associated with rediscovery (e.g. large species) and that are also associated with factors that negatively influence rediscovery (e.g. those occupying small islands) are more likely to be extinct. Our results may foster pragmatic search protocols that prioritise lost species likely to still exist.

Expert range maps of global mammal distributions harmonised to three taxonomic authorities.

Aim: Comprehensive, global information on species' occurrences is an essential biodiversity variable and central to a range of applications in ecology, evolution, biogeography and conservation. Expert range maps often represent a species' only available distributional information and play an increasing role in conservation assessments and macroecology. We provide global range maps for the native ranges of all extant mammal species harmonised to the taxonomy of the Mammal Diversity Database (MDD) mobilised from two sources, the Handbook of the Mammals of the World (HMW) and the Illustrated Checklist of the Mammals of the World (CMW). Location: Global. Taxon: All extant mammal species. Methods: Range maps were digitally interpreted, georeferenced, error-checked and subsequently taxonomically aligned between the HMW (6253 species), the CMW (6431 species) and the MDD taxonomies (6362 species). Results: Range maps can be evaluated and visualised in an online map browser at Map of Life (mol.org) and accessed for individual or batch download for non-commercial use. Main conclusion: Expert maps of species' global distributions are limited in their spatial detail and temporal specificity, but form a useful basis for broad-scale characterizations and model-based integration with other data. We provide georeferenced range maps for the native ranges of all extant mammal species as shapefiles, with species-level metadata and source information packaged together in geodatabase format. Across the three taxonomic sources our maps entail, there are 1784 taxonomic name differences compared to the maps currently available on the IUCN Red List website. The expert maps provided here are harmonised to the MDD taxonomic authority and linked to a community of online tools that will enable transparent future updates and version control.

Impacts of land cover change on the plant resources of an endangered pollinator.

One of the key drivers of pollinator declines is land cover change. We documented for the first time the impacts of over three decades of land cover change in Mexico on the plant resources of an endangered migratory pollinator, the Mexican long-nosed bat, Leptonycteris nivalis. This species is considered endangered under national and international criteria due to population declines over 50% in the past 10 years. Pregnant females of this bat species migrate every year following the blooms of Agave spp. from central Mexico to the southern United States; moving pollen over its 1,200 km long migratory corridor and pollinating distant populations of Agave spp. Increases in human populations density and agricultural expansion may be reducing agave habitat over time. The objective of our study is to understand the land cover change trends in the northern range of the bat and identify potential fragmentation patterns in the region. We analyzed changes that occurred in three vegetation types where agaves are found in five time periods 1985, 1993, 2002, 2007 and 2011. The area of the three vegetation types selected was reduced by using only the overlap with potential agave habitat created with ecological niche modeling algorithms to obtain the available agave habitat. We then calculated fragmentation metrics for each period. We found a significant portion of habitat lost mainly due to expansion in agriculture. The total number of patches increased after 1985. Only 9% of the available agave habitat in 2011 is inside the limits of protected areas. We recommend restoring agave populations in depleted areas to help prevent soil erosion and provide multiple socio-economic benefits for the region in the short term, and, in the long-term maintaining foraging resources for nectar-feeding bats.

Author Correction: Climate change, range shifts, and the disruption of a pollinator-plant complex.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Climate change, range shifts, and the disruption of a pollinator-plant complex.

Climate change has significant impacts on the distribution of species and alters ecological processes that result from species interactions. There is concern that such distribution shifts will affect animal-plant pollination networks. We modelled the potential future (2050 and 2070) distribution of an endangered migratory bat species (Leptonycteris nivalis) and the plants they pollinate (Agave spp) during their annual migration from central Mexico to the southern United States. Our models show that the overlap between the Agave and the endangered pollinating bat will be reduced by at least 75%. The reduction of suitable areas for Agave species will restrict the foraging resources available for the endangered bat, threatening the survival of its populations and the maintenance of their pollination service. The potential extinction of the bat L. nivalis will likely have negative effects on the sexual reproduction and genetic variability of Agave plants increasing their vulnerability to future environmental changes.

Species Identity Supersedes the Dilution Effect Concerning Hantavirus Prevalence at Sites across Texas and México.

Recent models suggest a relationship exists between community diversity and pathogen prevalence, the proportion of individuals in a population that are infected by a pathogen, with most inferences tied to assemblage structure. Two contrasting outcomes of this relationship have been proposed: the "dilution effect" and the "amplification effect." Small mammal assemblage structure in disturbed habitats often differs from assemblages in sylvan environments, and hantavirus prevalence is often negatively correlated with habitats containing high species diversity via dilution effect dynamics. As species richness increases, prevalence of infection often is decreased. However, anthropogenic changes to sylvan landscapes have been shown to decrease species richness and/or increase phylogenetic similarities within assemblages. Between January 2011 and January 2016, we captured and tested 2406 individual small mammals for hantavirus antibodies at 20 sites across Texas and México and compared differences in hantavirus seroprevalence, species composition, and assemblage structure between sylvan and disturbed habitats. We found 313 small mammals positive for antibodies against hantaviruses, evincing an overall prevalence of 9.7% across all sites. In total, 40 species of small mammals were identified comprising 2 taxonomic orders (Rodentia and Eulipotyphla). By sampling both habitat types concurrently, we were able to make real-world inferences into the efficacy of dilution effect theory in terms of hantavirus ecology. Our hypothesis predicting greater species richness higher in sylvan habitats compared to disturbed areas was not supported, suggesting the characteristics of assemblage structure do not adhere to current conceptions of species richness negatively influencing prevalence via a dilution effect.

In situ effects of pesticides on amphibians in the Sierra Nevada.

For more than 20 years, conservationists have agreed that amphibian populations around the world are declining. Results obtained through laboratory or mesocosm studies and measurement of contaminant concentrations in areas experiencing declines have supported a role of contaminants in these declines. The current study examines the effects of contaminant exposure to amphibians in situ in areas actually experiencing declines. Early larval Pseudacris regilla were translocated among Lassen Volcanic, Yosemite and Sequoia National Parks, California, USA and caged in wetlands in 2001 and 2002 until metamorphosis. Twenty contaminants were identified in tadpoles with an average of 1.3-5.9 (maximum = 10) contaminants per animal. Sequoia National Park, which had the greatest variety and concentrations of contaminants in 2001, also had tadpoles that experienced the greatest mortality, slowest developmental rates and lowest cholinesterase activities. Yosemite and Sequoia tadpoles and metamorphs had greater genotoxicity than those in Lassen during 2001, as determined by flow cytometry. In 2001 tadpoles at Yosemite had a significantly higher rate of malformations, characterized as hemimelia (shortened femurs), than those at the other two parks but no significant differences were observed in 2002. Fewer differences in contaminant types and concentrations existed among parks during 2002 compared to 2001. In 2002 Sequoia tadpoles had higher mortality and slower developmental rates but there was no difference among parks in cholinesterase activities. Although concentrations of most contaminants were below known lethal concentrations, simultaneous exposure to multiple chemicals and other stressors may have resulted in lethal and sublethal effects.

Survey for antibody to hantaviruses in Tamaulipas, Mexico.

Wild rodents (n=248) were trapped in two ecologically distinct sites at El Cielo Biosphere Reserve in the state of Tamaulipas, Mexico, during the summer of 2003. Samples from 199 individuals were tested for Hantavirus antibodies by an indirect enzyme-linked immunosorbent assay (ELISA). Hantavirus antibodies to recombinant Sin Nombre virus nucleocapsid protein were found in seven rodents (3.5%) of a single species, Peromyscus levipes. Antibody-positive rodents were found only in the Cloud Forest site, which had lower rodent species diversity than the Tropical Subdecidous Forest site. Although the identity of the virus in P. levipes remains to be determined, our study provides further evidence that Hantavirus antibody-positive individuals are prevalent in the rodent fauna of Mexico. This is the first survey for Hantavirus antibodies in the rodent fauna of Tamaulipas and the first report of P. levipes as a potential host for a Hantavirus.

The status of the world's land and marine mammals: diversity, threat, and knowledge.

Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action.

Home range perturbations in Tamias striatus : Food supply as a determinant of home range and density.

A 12-week experimental study on the responses of home range size and population density of eastern chipmunks, Tamias striatus, to perturbations in food resources was conducted at the Pymatuning Laboratory of Ecology in Pennsylvania. The study involved a total of 97 animals and 1,036 captures. Home ranges were determined for all animals marked and captured four or more times. Mean home ranges were calculated for three different experimental periods; a before-seeding period, a seeding period, during which an essentially unlimited supply of a preferred food (sunflower seeds) was available, and a post-seeding period when all seeds were withdrawn. Home ranges during the seeding period contracted in response to the food source supplied in seed trays distributed throughout the plot. The differences between the before and during mean home ranges was significant (P<0.05). Home ranges subsequently expanded after removal of the seeds. The population density also increased over 50% during the seeding period, both in response to the abundant food source and the contraction of resident home ranges. The density subsequently declined to its initial level in the post-seeding period. The replacement of home ranges of chipmunks which died during the study by the establishment of new, similar home ranges by immigrants, and the expansion of existing home ranges by residents into the vacated areas was also observed.