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2012

Safouhi, Hassan, Gaudreau, Philippe J. , Slevinsky, Richard M.

Abstract. We use the recently developed algorithm for the G(1) n transformation to approximate tail probabilities of the normal distribution, the gamma distribution, the student’s t-distribution, the inverse Gaussian distribution, and Fisher’s F distribution. Using this algorithm, which can be...

2001-01-01

Holt, R. D., Lewis, Mark A., Keitt, T. H.

All species’ ranges are the result of successful past invasions. Thus, models of species’ invasions and their failure can provide insight into the formation of a species’ geographic range. Here, we study the properties of invasion models when a species cannot persist below a critical population...

2015-01-01

Potapov, Alex, Merrill, Evelyn, Pybus, Margo, Lewis, Mark A.

We consider the problem of estimating the basic reproduction number R0 from data on prevalence dynamics at the beginning of a disease outbreak. We derive discrete and continuous time models, some coefficients of which are to be fitted from data. We show that prevalence of the disease is...

2016-01-01

Avgar, Tal, Potts, Jonathan R., Lewis, Mark A., Boyce, Mark S.

A resource selection function is a model of the likelihood that an available spatial unit will be used by an animal, given its resource value. But how do we appropriately define availability? Step selection analysis deals with this problem at the scale of the observed positional data, by matching...

2006-01-01

McCauley, E., Lewis, Mark A., Lutscher, F.

The question how aquatic populations persist in rivers when individuals are constantly lost due to downstream drift has been termed the “drift paradox.” Recent modeling approaches have revealed diffusion-mediated persistence as a solution. We study logistically growing populations with and...

2014-01-01

Peacock, Stephanie J., Connors, Brendan M., Krkošek, Martin, Irvine, James R., Lewis, Mark A.

The impact of parasites on hosts is invariably negative when considered in isolation, but may be complex and unexpected in nature. For example, if parasites make hosts less desirable to predators then gains from reduced predation may offset direct costs of being parasitized. We explore these...

2017-04-01

Guillaume Bastille-Rousseau, Dennis L. Murray, James A. Schaefer, Mark A. Lewis, Shane P. Mahoney, Jonathan R. Potts

Movement influences a myriad of ecological processes operating at multiple spatial and temporal scales. Yet our understanding of animal movement is limited by the resolution of data that can be obtained from individuals. Traditional approaches implicitly assume that movement decisions are made at...

2016-01-01

Goodsman, Devin W., Lewis, Mark A.

Dispersal can push population density below strong Allee thresholds ensuring the demise of small founding populations. As a result, for isolated populations of dispersing organisms, the minimum founding population size that enables establishment can be quite different from the Allee threshold. 2....

2002-01-01

Lewis, Mark A., Bingtuan Li, Hans F. Weinberger

 One crucial measure of a species' invasiveness is the rate at which it spreads into a competitor's environment. A heuristic spread rate formula for a spatially explicit, two-species competition model relies on `linear determinacy' which equates spread rate in the full nonlinear model with spread...

2020-01-01

S. M. Fischer, M. Beck, L.-M. Herborg, M. A. Lewis

Human traffic along roads can be a major vector for infectious diseases and invasive species. Though most road traffic is local, a small number of long-distance trips can suffice to move an invasion or disease front forward. Therefore, understanding how many agents travel over long distances and...