Adding pattern and process to eco-evo theory and applications.

Eco-evolutionary dynamics result when interacting biological forces simultaneously produce demographic and genetic population responses. Eco-evolutionary simulators traditionally manage complexity by minimizing the influence of spatial pattern on process. However, such simplifications can limit their utility in real-world applications. We present a novel simulation modeling approach for investigating eco-evolutionary dynamics, centered on the driving role of landscape pattern. Our spatially-explicit, individual-based mechanistic simulation approach overcomes existing methodological challenges, generates new insights, and paves the way for future investigations in four focal disciplines: Landscape Genetics, Population Genetics, Conservation Biology, and Evolutionary Ecology. We developed a simple individual-based model to illustrate how spatial structure drives eco-evo dynamics. By making minor changes to our landscape's structure, we simulated continuous, isolated, and semi-connected landscapes, and simultaneously tested several classical assumptions of the focal disciplines. Our results exhibit expected patterns of isolation, drift, and extinction. By imposing landscape change on otherwise functionally-static eco-evolutionary models, we altered key emergent properties such as gene-flow and adaptive selection. We observed demo-genetic responses to these landscape manipulations, including changes in population size, probability of extinction, and allele frequencies. Our model also demonstrated how demo-genetic traits, including generation time and migration rate, can arise from a mechanistic model, rather than being specified a priori. We identify simplifying assumptions common to four focal disciplines, and illustrate how new insights might be developed in eco-evolutionary theory and applications by better linking biological processes to landscape patterns that we know influence them, but that have understandably been left out of many past modeling studies.

Parasitism in heterogeneous landscapes: Association between conserved habitats and gastrointestinal parasites in populations of wild mammals.

Parasites constitute essential elements of biodiversity, playing fundamental roles for the functioning and configuration of any ecosystem. The continuous and accelerated human expansion into previously pristine territories is changing landscape structure and climatic regimes that could alter host - parasite dynamics. We explore the influence of landscape structure and habitat quality on gastrointestinal parasites in several species of mammals inhabiting remnants of tall evergreen forest within a matrix of anthropic vegetation. Here, we record 32 taxa of gastrointestinal parasites with nematodes as the most diverse group. Landscape variables such as forest edge density, river density and percentage of conserved habitat were among the best predictors of gastrointestinal parasites. Parasite species richness increased with a higher proportion of conserved habitat, but hosts living in disturbed areas show higher intensity of infection. The results presented here indicate that parasites are susceptible to habitat perturbation. It is pertinent to keep monitoring wildlife health in human dominated landscapes to understand disease dynamics, zoonotic risk, and ecosystem health.

Lithium for Carbamazepine-Induced Syndrome of Inappropriate Antidiuretic Hormone.

OBJECTIVES: To examine the effectiveness of low-dose lithium carbonate for managing carbamazepine-induced hyponatremia. METHODS: Single case study in an 88 year old man with bipolar illness and vascular dementia who had failed to respond to other mood stabilizers. RESULTS: The patient had developed hyponatremia on two separate occasions when treated with carbamazepine. Introduction of low-dose lithium resulted in prompt normalization of serum sodium levels, which was maintained for the subsequent 8 weeks. CONCLUSIONS: Carbamazepine may sometimes be the best or only viable treatment option for patients with bipolar illness or other conditions. When its use is complicated by syndrome of inappropriate ADH, dose reduction and fluid restriction are the simplest options but, if ineffective, addition of lithium may be a feasible, albeit somewhat complicated, alternative.

RETROSPECTIVE STUDY EVALUATING ASSOCIATIONS BETWEEN MIDLINE BRAIN SHIFT ON MAGNETIC RESONANCE IMAGING AND SURVIVAL IN DOGS DIAGNOSED WITH MENINGOENCEPHALITIS OF UNKNOWN ETIOLOGY.

Difficulty has been encountered when trying to identify ante mortem prognostic indicators for dogs with meningoencephalitis of unknown etiology (MUE). Identifying MRI imaging parameters associated with prognosis may impact treatment decision-making for clinician and owner. Our hypotheses for this retrospective cohort study are that dogs diagnosed with MUE that had midline shift on brain MRI would have a poorer survival compared to dogs without midline shift; and that younger age, lower weight, and low cerebrospinal fluid (CSF) cell count would be correlated with improved survival. Medical records were reviewed from two institutions. Inclusion criteria included: clinical signs referable to intracranial disease, brain MRI at presentation, abnormal CSF analysis, and negative infectious disease testing. Magnetic resonance imaging scans were evaluated for midline shift using the T2-weighted transverse image at the interthalamic adhesion and at the site of maximal deviation. Fifty-two dogs met the inclusion criteria. Median midline deviation was 0.12 cm. Median survival for dogs with no shift was 906 days and with shift was 84 days. Survival was not significantly different between groups (P = 0.11). This remained true when correcting for age (P = 0.22) and CSF TNCC (total nucleated cell count) (P = 0.12). Age at the time of diagnosis (P = 0.02) and CSF TNCC (P = 0.03) were significantly associated with survival. Cerebrospinal fluid protein value (P = 0.84) and weight (P = 0.82) were not significantly associated with survival. In this study of 52 dogs with MUE, MRI evidence of midline brain shift between 0.04 and 0.3 cm at the level of the interthalamic adhesion was not associated with shorter survival.