Behavioral states in space and time: understanding landscape use by an invasive mammal

Animal movement models can be used to understand species behavior and assist with implementation of management activities. We explored behavioral states of an invasive wild pig (Sus scrofa) population that recently colonized central Michigan, USA, 2014–2018. To quantify environmental factors related to wild pig movement ecology and spatio-temporal landscape use, we predicted wild pig behavioral states relative to land cover type, landscape structure (i.e., edge and patch cohesion), and weather conditions. We used global positioning system (GPS)-collars and monitored 8 wild pigs from 2014–2018. We fit local convex hulls and calculated movement metrics revealing 3 wild pig behavioral states (resting, exploratory, and relocating) and constructed a 3-level model to predict behavioral state probabilities relative to biotic and abiotic conditions. Probabilities of exploratory and resting behaviors were higher nearer to riparian and open herbaceous cover types (oftentimes emergent marsh), indicating that these cover types provided security cover during activity and bedding. Hard mast cover types had a strong positive association with relocating behaviors. More cohesive patches of agriculture and shrub cover types were associated with higher probabilities of exploratory behaviors, while resting was more likely in continuous patches of agriculture (mostly mid-summer corn). The probability of exploratory behaviors increased exponentially with warming ambient temperature. Our results may be used by managers to develop control strategies conducive to landscape and environmental conditions where the likelihood of encountering wild pigs is highest or targeting wild pigs when in a behavioral state most vulnerable to a particular removal technique.     

Acclimation of crown structure to drought in Quercus robur L.—intra- and inter-annual variation of abscission and traits of shed twigs

In pedunculate oak (Quercus robur L.) the architecture of the crown is strongly influenced by age and vigour of the tree. In old oak trees cladoptosis is a major mechanism on the transformation of crown architecture. Although it can be seen quite regularly, the causes and timing of shedding of twigs as well as the quantity of affected branches remain unclear. Because abscission is often used as an indicator of reduced vigour or stress in the assessment of stand and ornamental tree health, it deserves detailed investigation, especially in the context of oak decline. We studied the inter- and intra-annual variation of abscission in six stands across the eastern part of Germany in order to identify possible triggering events and controlling factors of abscission.On average, the number of twigs abscised per year increased from 1999 to 2001. While in 1999 approximately 100 abscised twigs per m² per year were shed, this number increased to 250 per m² in 2001. The majority of twigs was actively shed, a significant proportion of the remaining twigs was partly abscised. Only a small part of the abscised twigs had leaves attached to them. From June to September 20 per cent of the twigs had leaves, in the remaining months of the year less than 10 per cent.The analysis of almost 30,000 twig fragments over the course of 3 years demonstrated at least partial control by the tree of the process of abscission. The loss of the terminal bud and the formation of a male flower are traits correlated with abscission.Our data do not support the widely held belief that cladoptosis is mainly an immediate reaction to drought stress that reduces transpiring leaf area. The proportion of leafy twigs was quite low and the main peak of abscission occurred in late autumn, thus having little immediate effect on transpiration. In addition, we observed a time lag of 3 weeks between the onset of drought stress and increased levels of abscission.     

Excitotoxic loss of post-synaptic sites is distinct temporally and mechanistically from neuronal death

Dendritic degeneration and loss of synaptic proteins are early events correlated with functional decline in neurodegenerative disease. The temporal and mechanistic relationship between synapse loss and cell death, however, remains unclear. We used confocal microscopy and image processing to count post-synaptic sites on rat hippocampal neurons by expressing post-synaptic density protein 95 fused to green fluorescent protein. Fluorescent puncta co-localized with neurotransmitter release sites, NMDA-induced Ca²⁺ increases and NMDA receptor immunoreactivity. During excitotoxic neurodegeneration, synaptic sites were lost and synaptic transmission impaired. These changes were mediated by NMDA receptors and required Ca²⁺-dependent activation of the proteasome pathway. Tracking synapses from the same cell following brief neurotoxic insult revealed transient loss followed by recovery. The time-course, concentration-dependence and mechanism for loss of post-synaptic sites were distinct from those leading to cell death. Cells expressing p14ARF, which inhibits ubiquitination of post-synaptic density protein 95 and prevents loss of synaptic sites, displayed an increased sensitivity to glutamate-induced cell death. Thus, excitotoxic synapse loss may be a disease-modifying process rather than an obligatory step leading to cell death. These results demonstrate the importance of assessing synaptic function independent of neuronal survival during neurodegeneration and indicate that this approach will be useful for identifying toxins that degrade synaptic connections and for screening for agents that protect synaptic function.     

A Highlights from MBoC Selection: Locus-specific gene repositioning in prostate cancer

Genes occupy preferred spatial positions within interphase cell nuclei. However, positioning patterns are not an innate feature of a locus, and genes can alter their localization in response to physiological and pathological changes. Here we screen the radial positioning patterns of 40 genes in normal, hyperplasic, and malignant human prostate tissues. We find that the overall spatial organization of the genome in prostate tissue is largely conserved among individuals. We identify three genes whose nuclear positions are robustly altered in neoplastic prostate tissues. FLI1 and MMP9 position differently in prostate cancer than in normal tissue and prostate hyperplasia, whereas MMP2 is repositioned in both prostate cancer and hyperplasia. Our data point to locus-specific reorganization of the genome during prostate disease.     

Assessing invasive plant infestation and disturbance gradients in a freshwater wetland using a GIScience approach

The assessment of aquatic ecosystems requires information on biological and disturbance gradients in order to evaluate quality. As a result decision makers need improved monitoring tools for characterizing relationships between invasive species infestation and disturbance to make informed choices regarding wetland condition and management plans. The overarching goal of this research was to assess invasive plant infestation and disturbance gradients using a GIScience approach. The study was conducted in a fresh-water, coastal wetland in the Muskegon River watershed, Michigan, USA. Airborne hyperspectral imagery (20 bands, 440–880 nm) was classified for Phragmites australis distribution using the Spectral Angle Mapper algorithm. Indicator semivariograms were utilized to define landscape structure and associated spatial scales, and assist in creating a transect scheme to generate landscape pattern metrics quantifying valued ecosystem attributes. Hydrological modifications, as measured by an area-weighted fractal dimension index, served as a proxy for human disturbance and was found to moderately influence Phragmites percent cover (R ² = 0.4, n = 40), mean patch size (R ² = 0.5), and patch shape (R ² = 0.5). A general conclusion was that increased hydrological disturbances were correlated with increased infestation magnitude. The systematic approach executed in this study outlined how geospatial monitoring tools can be used as an assessment framework to provide more meaningful information that lends itself to comprehensive wetlands assessment.     

Untersuchungen zur Parasitierung und Prädation von Puparien der Brachfliege (Delia coarctata (Fall.))

Weidner, H.: Bestimmungstabellen der Vorratsschädlinge und des Hausungeziefers Mitteleuropas (mit einem Beitrag von Dr. Gisela Rack), 5., überarb. u. erw. Aufl., 328 S., 220 Abb., Stuttgart, New York, Gustav Fischer Verlag, 1993, 88.‐DM

Landolt, Z. Unsere Alpenflora. Gustav‐Fischer Verlag. Stuttgart‐Jena, 6. vollst. neu bearb. Aufl. 1992, 318 S., mit zahlr. Zeichnungen sowie 480 Farbabb. auf 120 Bildtafeln, 12 × 18 cm, geb. 48,‐DM, ISBN 3–437–20488–2