Estimating Black Bear Density Using DNA Data From Hair Snares

ABSTRACT DNA-based mark-recapture has become a methodological cornerstone of research focused on bear species. The objective of such studies is often to estimate population size; however, doing so is frequently complicated by movement of individual bears. Movement affects the probability of detection and the assumption of closure of the population required in most models. To mitigate the bias caused by movement of individuals, population size and density estimates are often adjusted using ad hoc methods, including buffering the minimum polygon of the trapping array. We used a hierarchical, spatial capture-recapture model that contains explicit components for the spatial-point process that governs the distribution of individuals and their exposure to (via movement), and detection by, traps. We modeled detection probability as a function of each individual's distance to the trap and an indicator variable for previous capture to account for possible behavioral responses. We applied our model to a 2006 hair-snare study of a black bear (Ursus americanus) population in northern New York, USA. Based on the microsatellite marker analysis of collected hair samples, 47 individuals were identified. We estimated mean density at 0.20 bears/km². A positive estimate of the indicator variable suggests that bears are attracted to baited sites; therefore, including a trap-dependence covariate is important when using bait to attract individuals. Bayesian analysis of the model was implemented in WinBUGS, and we provide the model specification. The model can be applied to any spatially organized trapping array (hair snares, camera traps, mist nests, etc.) to estimate density and can also account for heterogeneity and covariate information at the trap or individual level.     

Anatomy and Distribution of Secretory Glands and Other Emergences in Tofieldia (Liliaceae)

Secretory glands are rare in Liliaceae. We surveyed the scapesof herbarium specimens of all 23 species of Tofieldia and found13 with glabrous scapes, two with sparse emergences on a fewspecimens, and eight that invariably bore emergences which rangedfrom clearly secretory to clearly non-secretory. Gland-bearingspecies are concentrated in North America. Paraffin sectionsshowed anatomical differences among the emergences. Field-fixedscapes of T. glutinosa, with secretory glands, were studiedby the paraffin method and scanning electron microscopy. Themost distinctive feature is a distal pore where usually oneor two epidermal cells appear to be lacking, thereby exposingthe internal, presumably secretory, cells. The secretory productin T. glutinosa is tasteless, colourless, and sticky to thetouch.     

The influence of age and season on dispersal and recapture of Anopheles culicifacies in Sri Lanka

Abstract. 1. Three mark—release—recapture experiments with Anopheles culicifacies were carried out at different seasons in Sri Lanka. Blood fed females were collected daily in cattle baited huts, marked with fluorescent powder and released in the same village. In two of the experiments males and females were reared, marked when newly emerged, and released. The recapture rates were recorded in the same village and in a second village 2 km away.
2. The mosquitoes marked when already mature yielded an estimate that 2–7% of the mosquitoes in the second village had flown from the first. The recapture rate of reared mosquitoes in the first village was much lower than with those marked when already mature. This difference could be at least partly attributed to a tendency to disperse when young, as shown by the considerable number of recaptures of young mosquitoes in the second village.
3. By varying the colour used for marking, estimates were made of the amount of dispersal from hut to hut in the first village, the daily survival rate and the proportion of the wild population resting in the collecting huts each day.
4. Using the latter two estimates equations have been solved predicting the rate of build-up of the proportion of recaptures. These predictions were compared with the observed results. The data on dispersal are discussed in relation to possible method for delaying the build-up of insecticide resistance.     

Amplification and analysis of human DNA present in mosquito bloodmeals

Abstract. DNA fingerprinting should permit the identification of individual human hosts of haematophagous arthropods, providing epidemi-ologically useful information, for example, the biting rates on different people and the impact of insecticide-impregnated bednets.
Investigations reported here demonstrate that it is possible to extract, amplify and fingerprint human DNA from the bloodmeals of individual female Anopheles gambiae mosquitoes kept at 24^oC for up to 10–15 h post-ingestion.     

A ZYGOTE COULD BE A HUMAN: A DEFENCE OF CONCEPTIONISM AGAINST FISSION ARGUMENTS

In this paper I defend the view that a zygote is a human from the fission objection that is widely thought to be decisive against the view. I do so, drawing upon a recent discussion of this issue by John Burgess, by explaining in detail the metaphysical position the proponent of the view should adopt in order to rebut the objection.     

Serological identification and quantification of potato cyst nematodes from clean cysts and processed soil samples

Two monoclonal antibodies which specifically recognise each of the two species of potato cyst nematodes (PCN) and do not cross react with other species of soil nematodes, were used successfully in an immunoassay to identify and quantify PCN species using clean cysts and mixed populations. These antibodies show reactivity only towards antigens prepared from live eggs and they recognise antigens which are easily released from the nematodes. The results presented in this paper show that serological identification and quantification of PCN, not only from clean cysts but also from processed soil samples is achievable. A simple procedure to recover nematodes from soil samples and then to release nematode antigens was devised. The use of these procedures and the immunoassay for quantification of PCN was validated in tests with soil samples from Northern Portugal. The flotation method proved to be as efficient as the Fen wick Can for cyst recovery from soil samples. A significant correlation was obtained between results from immunoassay estimates and the traditional method of cyst picking and egg counting. The amount of organic matter (OM) present in the soil samples affected the sensitivity of the immunoassay but quantification of nematodes extracted from soil samples was possible with soils containing up to 14% of OM. The challenge remains to optimise the extraction procedures and the immunoassay, in practical conditions with highly organic soils containing cysts of different sizes and ages.