Data from: How topography induces reproductive asynchrony and alters gypsy moth invasion dynamics

1. Reproductive asynchrony, a temporal mismatch in reproductive maturation between an individual and potential mates, may contribute to mate-finding failure and Allee effects that influence the establishment and spread of invasive species. Variation in elevation is likely to promote variability in maturation times for species with temperature-dependent development, but it is not known how strongly this influences reproductive asynchrony or the population growth of invasive species. 2. We examined whether spatial variation in reproductive asynchrony, due to differences in elevation and local heterogeneity in elevation (hilliness), can explain spatial heterogeneity in the population growth rate of the gypsy moth, Lymantria dispar (L.), along its invasion front in Virginia and West Virginia, USA. 3. We used a spatially explicit model of the effects of reproductive asynchrony on mating success to develop predictions of the influences of elevation and elevational heterogeneity on local population growth rates. Population growth rates declined with increased elevation and more modestly with increased elevational heterogeneity. As in earlier work, we found a positive relationship between the population growth rate and the number of introduced egg masses, indicating a demographic Allee effect. At high elevations and high heterogeneity in elevation, the population growth rate was lowest and the density at which the population tended to replace itself (i.e., the Allee threshold) was highest. 4. An analysis of 22 years of field data also showed decreases in population growth rates with elevation and heterogeneity in elevation that were largely consistent with the model predictions. 5. These results highlight how topographic characteristics can affect reproductive asynchrony and influence mate-finding Allee effects in an invading non-native insect population. Given the dependence of developmental rates on temperature in poikilotherms, topographic effects on reproductive success could potentially be important to the population dynamics of many organisms.field_data_tabularThese data represent gypsy moth population growth rates, topographic characteristics, and resource density over 22850 1x1 km locations in western Virginia and West Virginia, USA. They were derived from a combination of sources. Gypsy moth population data were derived from pheromone-baited trap catch data provided by the gypsy moth Slow the Spread Program, Inc. The basal area of gypsy moth preferred host trees is from: Morin, et al. 2005. Mapping host-species abundance of three major exotic forest pests. USDA Forest Service Research Paper NE-726. Topographic variables were derived from a digital elevation model from the National Elevation Dataset, United States Geologic Survey (2009). Please find additional details in the ReadMe file.lambda_wgtlag.csvmating_success_model_commentedR code for a model of gypsy moth mating success with phenology varying due to changes in elevation and latitude. Comments to aid in understanding the model are provided in-code