Most pathogens threatening to cause extinction of a host species are maintained on one or more reservoir hosts, in addition to the species that is threatened by disease. Further, most conventional host-pathogen theory assumes that transmission is related to host density, and therefore a pathogen should become extinct before its sole host. Tasmanian devil facial tumor disease is a recently emerged infectious cancer that has led to massive population declines and grave concerns for the future persistence of this largest surviving marsupial carnivore. Here we report the results of mark-recapture studies at six sites and use these data to estimate epidemiological parameters critical to both accurately assessing the risk of extinction from this disease and effectively managing this disease threat. Three sites were monitored from before or close to the time of disease arrival, and at three others disease was well established when trapping began, in one site for at least 10 years. We found no evidence for sex-specific differences in disease prevalence and little evidence of consistent seasonal variation in the force of infection. At all sites, the disease was maintained at high levels of prevalence (>50% in 2-3-year-old animals), despite causing major population declines. We also provide the first estimates of the basic reproductive rate R0 for this disease. Using a simple age-structured deterministic model, we show that our results are not consistent with transmission being proportional to the density of infected hosts but are consistent with frequency-dependent transmission. This conclusion is further supported by the observation that local disease prevalence in 2-3-year-olds still exceeds 50% at a site where population density has been reduced by up to 90% in the past 12 years. These findings lend considerable weight to concerns that this host-specific pathogen will cause the extinction of the Tasmanian devil. Our study highlights the importance of rapidly implementing monitoring programs to determine how transmission depends on host density and emphasizes the need for ongoing management strategies involving a disease-free "insurance population," along with ongoing field monitoring programs to confirm whether local population extinction occurs.

Late Quaternary megafauna extinctions impoverished mammalian diversity worldwide. The causes of these extinctions in Australia are most controversial but essential to resolve, because this continent-wide event presaged similar losses that occurred thousands of years later on other continents. Here we apply a rigorous metadata analysis and new ensemble-hindcasting approach to 659 Australian megafauna fossil ages. When coupled with analysis of several high-resolution climate records, we show that megafaunal extinctions were broadly synchronous among genera and independent of climate aridity and variability in Australia over the last 120,000 years. Our results reject climate change as the primary driver of megafauna extinctions in the world's most controversial context, and instead estimate that the megafauna disappeared Australia-wide ∼13,500 years after human arrival, with shorter periods of coexistence in some regions. This is the first comprehensive approach to incorporate uncertainty in fossil ages, extinction timing and climatology, to quantify mechanisms of prehistorical extinctions.

Successful establishment and range expansion of non-native species often require rapid accommodation of novel environments. Here, we use commongarden experiments to demonstrate parallel adaptive evolutionary response to a cool climate in populations of wall lizards (Podarcis muralis) introduced from southern Europe into England. Low soil temperatures in the introduced range delay hatching, which generates directional selection for a shorter incubation period. Non-native lizards from two separate lineages have responded to this selection by retaining their embryos for longer before ovipositionhence reducing the time needed to complete embryogenesis in the nest-and by an increased developmental rate at low temperatures. This divergence mirrors local adaptation across latitudes and altitudes within widely distributed species and suggests that evolutionary responses to climate can be very rapid. When extrapolated to soil temperatures encountered in nests within the introduced range, embryo retention and faster developmental rate result in one to several weeks earlier emergence compared with the ancestral state. We show that this difference translates into substantial survival benefits for offspring. This should promote short-and long-term persistence of nonnative populations, and ultimately enable expansion into areas that would be unattainable with incubation duration representative of the native range.

Summary 1.Culling, either of all animals or infected animals only, is often suggested as a way of managing infectious diseases in wildlife populations. However, replicated experiments to investigate culling strategies are often impractical because of costs and ethical issues. Modelling therefore has an important role. Here, we describe a suite of models to investigate the culling of infected animals to control an infectious cancer in the Tasmanian devil Sarcophilus harrisii. 2. The Tasmanian devil is threatened by an infectious cancer, Tasmanian devil facial tumour disease. We developed deterministic susceptible, exposed and infectious (SEI) models with differing ways of incorporating the time delays inherent in the system. We used these to investigate the effectiveness for disease suppression of various strategies for the removal of infected animals. 3. The predictions of our models were consistent with empirical time series on host population dynamics and disease prevalence. This implies that they are capturing the essential dynamics of the system to a plausible extent. 4. A previous empirical study has shown that removals every 3 months did not appear to be sufficient to suppress disease in a semi-isolated infected population. Our models are in accordance with this observed result. The models further predict that while more frequent removals are more likely to be effective, the removal rate necessary to successfully eliminate disease may be too high to be achievable. 5. Synthesis and applications. Our results, in association with a previous experimental study, show that culling is unlikely to be a feasible strategy for managing Tasmanian devil facial tumour disease. Similar conclusions have been reached in studies of other wildlife diseases. We conclude that culling is rarely appropriate for controlling wildlife diseases and should only be attempted if models predict that it will be effective.

Confidence in fossil ages is a recognized constraint for understanding changes in archaeological and palaeontological records. Poor estimates of age can lead to erroneous inferences-such as timing of species arrival, range expansions and extinctions-preventing robust hypothesis testing of the causes and consequences of past events. Therefore, age reliability must be demonstrated before patterns and mechanisms are inferred. Here we present a generalized quality-rating scheme based on a two-stage set of objective criteria: first, our method assesses the reliability of an age regarding the dating procedure, and second, if the age is based on association, it assesses the confidence in its association with the target vertebrate fossil. We developed this quality rating specifically for Australian applications, but it could be applied to other regions and to longer timescales with some modification. Our method ranks ages in four categories of reliability (A* and A are reliable; B and C are unreliable). In our case study of the late Pleistocene megafauna of Sahul, accounting for reliability (i.e., accepting only reliable ages) reduced the number of useful records within chronologies by 70%; for most species, this greatly affects any inferences regarding the timing and possible drivers of extinction. Our method provides a simple, replicable and general tool for assessing the age quality of dated fossils, as well as provides a guide for selecting useful protocols and samples for dating. Disciplines Medicine and Health Sciences | Social and Behavioral Sciences Publication DetailsRodríguez-Reya, M., Herrando-Perez, S., Gillespie, R., Jacobs, Z., Saltréa, F., Brook, B. W., Prideaux, G. J., Roberts, R. present a generalized quality-rating scheme based on a two-stage set of objective criteria: 7 first, our method assesses the reliability of an age regarding the dating procedure, and second, 8 if the age is based on association, it assesses the confidence in its association with the target 9 vertebrate fossil. We developed this quality rating specifically for Australian applications, but 10 it could be applied to other regions and to longer timescales with some modification. Our