Spatial synchrony, that is, correlated population fluctuation over wide geographical areas, has been detected in diverse taxa and over various geographical scales. The most commonly suggested mechanisms to explain spatial synchrony include dispersal and regional stochasticity (i.e., ''the Moran effect''). We analyzed landscape-scale historical outbreak data for six forest insect species: spruce budworm (Choristoneura fumiferana), western spruce budworm (C. occidentalis), larch bud moth (Zeiraphera diniana), forest tent caterpillar (Malacosoma disstria), mountain pine beetle (Dendroctonus ponderosae), and gypsy moth (Lymantria dispar). We used a recently developed statistical method (the nonparametric covariance function) for quantifying the magnitude and spatial range of synchrony in both outbreak and corresponding weather data. The varying dispersal capabilities of the species enabled us to speculate on the relative importance of dispersal vs. the Moran effect as potential mechanisms behind the observed patterns. Our results indicated that spatial synchrony was not directly associated with dispersal capabilities at the spatial scales considered. In contrast, the spatial correlation in weather variables was high enough to account for the levels of synchrony observed in the outbreak data. Therefore, the Moran effect appeared to be the more dominant process affecting the spatial dynamics of these species at the landscape scale. In general, however, the synchrony in outbreaks declined more steeply with geographical distance than the correlation in the weather variables, breaking with the predictions of Moran's theorem. A more detailed analysis of gypsy moth outbreak data showed that local dynamics varied considerably in a spatially dependent manner. The existence of such variation violates one of the assumptions of the Moran's theorem, namely, that the dynamic properties of disjunct populations are identical. We used a simple theoretical model to demonstrate that such geographical variation in local population dynamics may indeed force synchrony to decline more rapidly with distance than the correlation in the environment.

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The gypsy moth has been present in North America for more than 100 years, and in many of the areas where it has become established outbreaks occur with varying degrees of periodicity. There also exists extensive spatial synchrony in the onset of outbreaks over large geographic regions. Density-dependent mortality clearly limits high-density populations, but there is little evidence for strong regulation of low-density populations. Predation by small mammals appears to be the major source of mortality affecting low-density populations, but because these are generalist predators and gypsy moths are a less preferred food item, mammals do not appear to regulate populations in a density-dependent fashion. Instead, predation levels appear to be primarily determined by small mammal abundance, which is in turn closely linked to the production of acorns that are a major source of food for overwintering predator populations. Mast production by host oak trees is typically variable among years, but considerable spatial synchrony in masting exists over large geographic areas. Thus, it appears that the temporal and spatial patterns of mast production may be responsible for the episodic and spatially synchronous behavior of gypsy moth outbreaks in North America. This multitrophic relationship among mast, predators, and gypsy moths represents a very different explanation of forest insect outbreak dynamics than the more widely applied theories based upon predator-prey cycles or feedbacks with host foliage quality.

We draw from cognitive science literature on rule‐based thinking to develop and empirically test a theoretical framework of entrepreneurial opportunity evaluation. We argue that entrepreneurs make use of socially constructed rules to discern the attractiveness of an opportunity, for them, specifically. Using conjoint analysis data of 498 decisions made by 62 entrepreneurs, we find that entrepreneurs' use of rules regarding opportunity novelty, resource efficiency, and worst‐case scenario significantly influences entrepreneurs' evaluations of opportunities and that individual differences in opportunity market and technology knowledge augment the effect of the rules on opportunity attractiveness. Additionally, we document that the worst‐case scenario diminishes the positive effect of other rule criteria (e.g. novelty, resource efficiency) on opportunity evaluation and that market and technology knowledge further influence the negative effects of the worst‐case scenario.

1 One expected effect of global climate change on insect populations is a shift in geographical distributions toward higher latitudes and higher elevations. Southern pine beetle Dendroctonus frontalis and mountain pine beetle Dendroctonus ponderosae undergo regional outbreaks that result in large-scale disturbances to pine forests in the south-eastern and western United States, respectively. 2 Our objective was to investigate potential range shifts under climate change of outbreak areas for both bark beetle species and the areas of occurrence of the forest types susceptible to them. 3 To project range changes, we used discriminant function models that incorporated climatic variables. Models to project bark beetle ranges employed changed forest distributions as well as changes in climatic variables. 4 Projected outbreak areas for southern pine beetle increased with higher temperatures and generally shifted northward, as did the distributions of the southern pine forests. 5 Projected outbreak areas for mountain pine beetle decreased with increasing temperature and shifted toward higher elevation. That trend was mirrored in the projected distributions of pine forests in the region of the western U.S. encompassed by the study. 6 Projected outbreak areas for the two bark beetle species and the area of occurrence of western pine forests increased with more precipitation and decreased with less precipitation, whereas the area of occurrence of southern pine forests decreased slightly with increasing precipitation. 7 Predicted shifts of outbreak ranges for both bark beetle species followed general expectations for the effects of global climate change and reflected the underlying long-term distributional shifts of their host forests.