Population spread in patchy landscapes under a strong Allee effect

Musgrave, Jeffrey; Girard, Alexandre; Lutscher, Frithjof

doi:10.1007/s12080-015-0252-1

Cited by 16 publications

(10 citation statements)

References 32 publications

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“…This is in accordance with the study by Musgrave et al . (), who have shown that the percentage of hostile patches at which populations collapse can depend on individuals’ movement behaviour, as introducing hostile patches can increase spread rates if individuals move fast enough.…”

Section: Discussionmentioning

confidence: 99%

Spread rates on fragmented landscapes: the interacting roles of demography, dispersal and habitat availability

Barros

Palmer

Bocedi

et al. 2016

Diversity and Distributions

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Aim We still lack a comprehensive understanding of the relative importance of demographic, dispersal and landscape characteristics on species' rates of range expansion (RRE) and on how these factors interact. Here, we provide an analysis of these effects for passive dispersers, by investigating how habitat characteristics, such as habitat quality, availability and fragmentation, interplay with species' dispersal characteristics in determining species' RRE. In addition, we assessed the predictability of RRE in cases where we have the knowledge of a species' demography, dispersal and habitat availability.Methods Using the newly available individual-based modelling platform, RANGESHIFTER we simulated the range expansion of species with different dispersal abilities, by varying mean dispersal distance and number of emigrants, on various landscapes. Landscapes varied in habitat quality (in terms of carrying capacity and species' growth rates) and in habitat availability (in terms of the proportion of suitable habitat and its degree of fragmentation).Results Our results show that 55% of the total variation in RRE was explained by our six main effects, being considerably faster in landscapes with more suitable habitat, but only slightly affected by the degree of habitat fragmentation. Also, synergies between the amount of suitable habitat and species dispersal characteristics had significant positive effects on range expansion. Notably, however, 33% of variation in RRE was not explained by any of the tested factors or interactions between them and can be considered inherent and irreducible uncertainty.Main conclusions Simulation-based approaches provide important insights into the drivers of RRE that are relevant for conservation planning. For instance, our results indicate when it is likely to be better to allocate resources to improve existing habitat rather than creating new habitat, and vice versa. Additionally, our results emphasize that there will often be substantial uncertainty in the RRE, which needs to be taken into account for ecological management.

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Section: Discussionmentioning

confidence: 99%

Spread rates on fragmented landscapes: the interacting roles of demography, dispersal and habitat availability

Barros

Palmer

Bocedi

et al. 2016

Diversity and Distributions

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“…Positive density dependence (Allee effects) generally leads to more restrictive conditions for invasion (Dewhirst and Lutscher , Musgrave et al. ). Density‐dependent movement can also affect rates of range expansion (Altwegg et al.…”

Section: Predicting Range Expansion In Heterogeneous Landscapesmentioning

confidence: 99%

Faster movement in nonhabitat matrix promotes range shifts in heterogeneous landscapes

Crone

Brown

Hodgson

et al. 2019

Ecology

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Ecologists often assume that range expansion will be fastest in landscapes composed entirely of the highest‐quality habitat. Theoretical models, however, show that range expansion depends on both habitat quality and habitat‐specific movement rates. Using data from 78 species in 70 studies, we find that animals typically have faster movement through lower‐quality environments (73% of published cases). Therefore, if we want to manage landscapes for range expansion, there is a trade‐off between promoting movement with nonhostile matrix, and promoting population growth with high‐quality habitat. We illustrate how this trade‐off plays out with the use of an exemplar species, the Baltimore checkerspot butterfly. For this species, we calculate that the expected rate of range expansion is fastest in landscapes with ~15% high‐quality habitat. Behavioral responses to nonhabitat matrix have often been documented in animal populations, but rarely included in empirical predictions of range expansion. Considering movement behavior could change land‐planning priorities from focus on high‐quality habitat only to integrating high‐ and low‐quality land cover types, and evaluating the costs and benefits of different matrix land covers for range expansion.

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“…Our model did not include an Allee effect, yet Allee effects play a role in many invasion processes. Even in a homogeneous landscape, there is no simple speed formula when an Allee effect is present, but two recent numerical and semi-analytical studies explored the impacts of landscape heterogeneity and Allee effect on invasion speeds Lutscher 2015, Musgrave et al 2015). Equally important, our model did not include an increased mortality risk in bad patches for the dispersing individuals (e.g., due to energy requirements or predation).…”

Section: Combined Behaviormentioning

confidence: 99%

Behavioral responses to resource heterogeneity can accelerate biological invasions

Lutscher

Musgrave

2017

Ecology

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The abundance and spatial distribution of resources in a landscape and the behavioral response of individuals determines whether and how fast an invasive species spreads in an environment. Whether and how landscape manipulations can be used to slow invasive species is of great interest, in particular in forest ecosystems, where tree removal, thinning, and increasing tree diversity are discussed as management options. Classically, the focus is on availability and accessibility of resources; more recent considerations include individual-level behavioral movement responses to a spatially heterogeneous resource distribution. We derive a novel model for insect-host dynamics that includes three common behavioral aspects of foraging: higher movement rate in resource-poor areas, lower ovipositioning rate in resource-poor areas, and movement preference for resource-rich areas. We show that each of these basic mechanisms can increase the speed of invasion in a source-sink landscape above that in a homogeneous landscape with larger overall resource availability. We parameterize our model and illustrate our results with data for emerald ash borer, a recent highly destructive forest pest in North America. Our results highlight the importance of empirical work on movement behavior in different landscape types and near the interface between types.

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Population spread in patchy landscapes under a strong Allee effect

Cited by 16 publications

References 32 publications

Spread rates on fragmented landscapes: the interacting roles of demography, dispersal and habitat availability

Spread rates on fragmented landscapes: the interacting roles of demography, dispersal and habitat availability

Faster movement in nonhabitat matrix promotes range shifts in heterogeneous landscapes

Behavioral responses to resource heterogeneity can accelerate biological invasions

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