Biology subjects

Scheele, B. C.

Publications and source records attributed to Scheele, B. C..

4 recordsLinked to original sources

bioRxiv2026

Over-the-horizon extinction risk assessment reveals rapidly shifting geographic and taxonomic priorities for conservation

A central challenge in conservation is understanding how climate change interacts with other global-change drivers to shape future species extinction risk, threatened-species hotspots, and the effectiveness of protected areas. Here, we use an integrated over-the-horizon forecasting framework to jointly model changing species range dynamics and shifts in extinction risk for 1,914 Australian terrestrial vertebrates to 2100. Our approach links ensemble species distribution models with machine-learning-based automated threat assessment, incorporating species traits, changing distributions of invasive species, and projections of land use and human population density. Under a high-emissions scenario, up to 109 species are projected to lose all climatically accessible habitat by 2100 and the number of threatened species is predicted to increase, while under a moderate emissions scenario (SSP1.26) the number of threatened species remains relatively stable, and up to 19 lose all climatically accessible habitat. Spatially, threatened-species richness becomes increasingly concentrated in southeastern Australia. These shifts elevate the representation of threatened species within existing protected areas, largely because extinctions and range contractions occur disproportionately outside protected areas. Our results highlight that the identity of at-risk species and the occurrence of threatened-species hotspots will change dramatically, underscoring the need for forward-looking conservation strategies that anticipate future biodiversity patterns.

ecology↗

bioRxiv2026

Imminent invasion of the chytrid fungus threatens the last naive amphibian biodiversity hotspots

While the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is driving catastrophic biodiversity loss worldwide, some amphibian communities persist seemingly unaffected despite occurring in climates conducive to pathogen establishment. These amphibian communities may remain epidemiologically naive. As mitigation of Bd is rarely successful after establishment, identifying remaining Bd-free refuges is imperative. Presently, the only known large-scale Bd-free refuge is the island of New Guinea (NG), safeguarding Australasias amphibian phylogenetic diversity otherwise devastated by Bd. Following extensive multi-year disease surveillance, we here uncover a second large-scale Bd-free refuge in the Sierra Nevada de Santa Marta (SNSM), a Neotropical biodiversity hotspot in northern Colombia. We detected no evidence of Bd in SNSM-wide screening, while we uncovered the presence of hypervirulent Bd-GPL in adjacent areas of the tropical Andes. Population genomic analyses in an SNSM-endemic anuran found no evidence for demographic bottlenecks indicative of cryptic epizootic decline. Niche modelling highlights the high risk for Bd establishment and Bd-induced declines in both the SNSM and NG, and the important role of lowland environmental barriers in restricting Bd invasion. Infection trials using three SNSM-endemic amphibians reveal varying disease susceptibility. Together, these data identify the SNSM as an epidemiologically naive refuge likely facing imminent Bd invasion, which could result in the loss of at least 25 endemic amphibian species. We highlight the urgent need for proactive conservation action and strict implementation of biosecurity to safeguard the unique and vast amphibian diversity of the worlds last major Bd-free refuges. Significance StatementAmphibian chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) has driven unprecedented global biodiversity loss. The Neotropics and Australasia comprise epicenters of declines. Identifying remaining Bd-free refuges is crucial to curb further amphibian extinctions, but so far contemporary absence of Bd has only been demonstrated for New Guinea. Here we identify the last known major Bd-free biodiversity hotspot in the Neotropics: the Sierra Nevada de Santa Marta (SNSM) in Colombia. Our results show that amphibian communities in this hotspot are immunologically naive despite occurrence of hypervirulent Bd lineages nearby and climatic conditions within the SNSM conducive to Bd-induced declines. This creates an imminent risk for Bd-driven declines and highlights the urgent need for preventive actions to avert another wave of biodiversity loss.

ecology↗

bioRxiv2020

Environmental DNA sampling in a terrestrial environment: methods to detect a critically endangered frog and a global pathogen

Environmental DNA techniques have become established as a useful tool for biological monitoring and are used extensively to determine species presence in aquatic systems. However, their application in terrestrial systems has been more limited, likely in part due to difficulties in choosing where to sample and ensuring that collected DNA reflects current species presence. We developed methods to sample eDNA in the terrestrial environment and trialled them under controlled and field conditions. We targeted three species, an elusive critically endangered frog, an abundant non-threatened frog, and the globally distributed amphibian skin pathogen chytrid fungus, which has been implicated in the decline of over 500 amphibian species. We used a sandpaper-sampling surface to trap DNA. After sampling, we washed the surface and filtered the wash water to gather material for DNA extraction and subsequent qPCR. Our controlled condition experiments demonstrated that frog and chytrid fungus DNA was detectable after as few as five contacts between a frog and the sampling surface. Furthermore, this DNA remained detectable after two weeks in cool, shaded, outdoor conditions. Our field experiments demonstrated that these techniques were transferable to natural habitats, where we detected both the common and rare amphibian target species, as well as chytrid fungus. Field sampling eDNA results were broadly consistent with those derived from conventional survey methods. Our methods have potential application in non-invasive sampling of amphibians and other species in terrestrial systems, broadening the applicability of eDNA techniques for species detection and monitoring.

ecology↗

bioRxiv2017

Disease mediated changes to life history and demography threaten the survival of European amphibian populations

Infectious diseases can influence the life history strategy of their hosts and such influences subsequently impact the demography of infected populations, reducing viability independently of increased mortality or morbidity. Amphibians are the most threatened group of vertebrates and emerging infectious diseases play a large role in their population declines. Viruses of genus Ranavirus are responsible for one of the deadliest of these diseases. To date no work has evaluated the impact of ranaviruses on host life-history post metamorphosis or population demographic structure at the individual level. In this study, we used skeletochronology and morphology to evaluate the impact of ranaviruses on the demography of populations of European common frog (Rana temporaria) in the United Kingdom. We compared ecologically similar populations that differed only in their historical presence or absence of ranaviral disease. Our results suggest that ranaviruses are associated with shifts in the age structure of infected populations, potentially caused by increased adult mortality and associated shifts in the life history of younger age classes. Population projection models indicate that such age truncation could heighten the vulnerability of frog populations to stochastic environmental challenges. Our individual level data provide further compelling evidence that the emergence of infectious diseases can alter host demography, subsequently increasing population vulnerability to additional stressors.

ecology↗