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Abstract: We live in a time where climate models predict future increases inenvironmental variability and biological invasions are becoming increasinglyfrequent. A key to developing effective responses to biological invasions inincreasingly variable environments will be estimates of their rates of spatialspread and the associated uncertainty of these estimates. Using stochastic,stage-structured, integro-difference equation models, we show analytically thatinvasion speeds are asymptotically normally distributed with a variance thatdecreases in time. We apply our methods to a simple juvenile-adult model withstochastic variation in reproduction and an illustrative example with publisheddata for the perennial herb, \emph{Calathea ovandensis}. These examplesbuttressed by additional analysis reveal that increased variability in vitalrates simultaneously slow down invasions yet generate greater uncertainty aboutrates of spatial spread. Moreover, while temporal autocorrelations in vitalrates inflate variability in invasion speeds, the effect of theseautocorrelations on the average invasion speed can be positive or negativedepending on life history traits and how well vital rates ``remember- thepast.



Author: Sebastian J. Schreiber, Maureen E. Ryan

Source: https://arxiv.org/







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