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Creators/Authors contains: "Grayson, Kristine L"

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  1. Abstract

    Studies of biological invasions at the macroscale or across multiple scales can provide important insights for management, particularly when localized information about invasion dynamics or environmental contexts is unavailable. In this study, we performed a macroscale analysis of the roles of invasion drivers on the local scale dynamics of a high‐profile pest,Lymantria dispar disparL., with the purpose of improving the prioritization of vulnerable areas for treatment. Specifically, we assessed the relative effects of various anthropogenic and environmental variables on the establishment rate of 8010 quadrats at a localized scale (5 × 5 km) across the entireL. dispartransition zone (the area encompassing the leading population edge, currently from Minnesota to North Carolina). We calculated the number of years from first detection ofL. disparin a quadrat to the year when probability of establishment ofL. disparwas greater than 99% (i.e., waiting time to establishment after first detection). To assess the effects of environmental and anthropogenic variables on each quadrat's waiting time to establishment, we performed linear mixed‐effects regression models for the full transition zone and three subregions within the zone. Seasonal temperatures were found to be the primary drivers of local establishment rates. Winter temperatures had the strongest effects, especially in the northern parts ofmore »the transition zone. Furthermore, the effects of some factors on waiting times to establishment varied across subregions. Our findings contribute to identifying especially vulnerable areas to furtherL. disparspread and informing region‐specific criteria by invasion managers for the prioritization of areas for treatment.

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  3. Abstract Aim

    Invasive species are ideal systems for testing geographical differences in performance traits and measuring evolutionary responses as a species spreads across divergent climates and habitats. The European gypsy moth,Lymantria dispar disparL. (Lepidoptera: Erebidae), is a generalist forest defoliator introduced to Medford, Massachusetts, USA in 1869. The invasion front extends from Minnesota to North Carolina and the ability of this species to adapt to local climate may contribute to its continuing spread. We evaluated the performance of populations along the climatic gradient of the invasion front to test for a relationship between climate and ecologically important performance traits.

    Location

    Eastern United States of America

    Taxon

    Lymantria dispar disparL. (Lepidoptera: Erebidae)

    Methods

    Insects from 14 populations across the US invasion front and interior of the invasive range were reared from hatch to adult emergence in six constant temperature treatments. The responses of survival, pupal mass and larval development time were analysed as a function of source climate (annual mean normal temperature), rearing temperature and their interaction using multiple polynomial regression.

    Results

    With the exception of female development time, there were no significant interactions between source climate and rearing temperature, indicating little divergence in the shape of thermal reaction norms among populations. Source population and rearingmore »temperature were significant predictors of survival and pupal mass. Independent of rearing temperature, populations from warmer climates had lower survival than those from colder climates, but attained larger body size despite similar development times. Larval development time was dependent on rearing temperature, but there were not consistent relationships with source climate.

    Main Conclusions

    Thermal adaptation can be an important factor shaping the spread of invasive species, particularly in the context of climate change. Our results suggest thatL. d. disparis highly plastic, but has undergone climate‐related adaptation in thermal performance and life‐history traits as it spread across North America.

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