The highs and lows of dispersal: how connectivity and initial population size jointly shape establishment dynamics in discrete landscapes

Morel‐Journel, Thibaut; Girod, Pierre; Mailleret, Ludovic; Auguste, Alexandra; Blin, Aurélie; Vercken, Elodie

doi:10.1111/oik.02718

Cited by 23 publications

(41 citation statements)

References 49 publications

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“…Presence of positive density-dependent dispersal analysis Using Approximate Bayesian Computation (ABC), we checked for the presence of positive density-dependent dispersal for Trichogramma chilonis in our experimental design by comparing two different scenarios, one with fixed dispersal and one with positive density-dependent dispersal (with a dependence of the form (7)). This analysis confirmed that the positive density-dependent dispersal scenario is the most likely, as suggested by a previous study with a comparable protocol (Morel-Journel et al, 2016). More details on the ABC analysis are presented as Supplementary Information S2.…”

Section: Experimental Study: Propagation Of a Parasitoid Wasp In A MIsupporting

confidence: 87%

When higher carrying capacities lead to faster propagation

Haond

Morel‐Journel

Lombaert

et al. 2018

Preprint

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This preprint has been reviewed and recommended by Peer Community In Ecology (https://dx.doi.org/10.24072/pci.ecology.100004). Finding general patterns in the expansion of natural populations is a major challenge in ecology and invasion biology. Classical spatio-temporal models predict that the carrying capacity (K) of the environment should have no influence on the speed (v) of an expanding population. We tested the generality of this statement with reactiondiffusion equations, stochastic individual-based models, and microcosms experiments with Trichogramma chilonis wasps. We investigated the dependence between K and v under different assumptions: null model (Fisher-KPP-like assumptions), strong Allee effects, and positive densitydependent dispersal. These approaches led to similar and complementary results. Strong Allee effects, positive density-dependent dispersal and demographic stochasticity in small populations lead to a positive dependence between K and v. A positive correlation between carrying capacity and propagation speed might be more frequent than previously expected, and be the rule when individuals at the edge of a population range are not able to fully drive the expansion.

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Section: Experimental Study: Propagation Of a Parasitoid Wasp In A MIsupporting

confidence: 87%

When higher carrying capacities lead to faster propagation

Haond

Morel‐Journel

Lombaert

et al. 2018

Preprint

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“…While individuals were able to move freely between patches by walking through pipes, the dispersal rates in this experimental system remained low. Previous experiments (Morel-Journel et al 2016) in similar conditions showed that most individuals remained in their natal patch, and no individual was ever found further that one patch away from its natal patch.…”

Section: Methodsmentioning

confidence: 83%

“…Dispersal mortality risks and Allee effects were considered separately during the simulations, and previous results by Morel-Journel et al (2016) concluded that T. chilonis suffered from no demographic Allee effect in this particular experimental setting. However, the two mechanisms can also influence each other.…”

Section: Discussionmentioning

confidence: 99%

“…Yet, the experiment showed that patches neighbouring small populations were less likely to be colonised. Indeed, small populations are less likely to produce enough successful dispersing individuals to colonise other patches (Morel-Journel et al 2016). Although the scale of habitat clustering we used in this study did not prevent dispersal between rich patches altogether, it made it more challenging.…”

Section: Discussionmentioning

confidence: 99%

“…The model used here is adapted from Morel-Journel et al (2016) and describes the dynamics of a population in a one-dimensional stepping-stone landscape W. This model aims at describing general population dynamics and bringing insight on invasion dynamics regardless of the species considered.…”

Section: Model and Simulationsmentioning

confidence: 99%

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Clustered or scattered? The impact of habitat quality clustering on establishment and early spread

Morel‐Journel¹,

Hautier²,

Vercken³

et al. 2018

Ecography

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The match between the environmental conditions of an introduction area and the preferences of an introduced species is the first prerequisite for establishment. Yet, introduction areas are usually landscapes, i.e. heterogeneous sets of habitats that are more or less favourable to the introduced species. Because individuals are able to disperse after their introduction, the quality of the habitat surrounding the introduction site is as critical to the persistence of introduced populations as the quality of the introduction site itself. Moreover, demographic mechanisms such as Allee effects or dispersal mortality can hamper dispersal and affect spread across the landscape, in interaction with the spatial distribution of favourable habitat patches. In this study, we investigate the impact of the spatial distribution of heterogeneous quality habitats on establishment and early spread. First, we simulated introductions in one‐dimensional landscapes for different dispersal rates and either dispersal mortality or Allee effects. The landscapes differed by the distribution of favourable and less favourable habitats, which were either clustered into few large aggregates of the same quality or scattered into multiple smaller ones. Second, we tested the predictions of simulations by performing experimental introductions of hymenopteran parasitoids (Trichogramma chilonis) in ‘clustered’ and ‘scattered’ microcosm landscapes. Results highlighted two impacts of the clustering of favourable habitat: by decreasing the risks of dispersal from the introduction site to unfavourable habitat early during the invasion, it increased establishment success. However, by increasing the distance between favourable habitat patches, it also hindered the subsequent spread of introduced species over larger areas.

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