The distinct phenotypic signatures of dispersal and stress in an arthropod model: from physiology to life history

Bonte

et al. 2019

Preprint

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ABSTRACTBackgroundA central tenet of the evolutionary theory of communities is that competition impacts evolutionary processes such as local adaptation. Species in a community exert a selection pressure on other species and may drive them to extinction. We know, however, very little about the influence of unsuccessful or ghost species on the evolutionary dynamics within the community.MethodsHere, we studied the long-term influence of a ghost competitor on the performance of a more successful species using experimental evolution. We transferred the spider mite Tetranychus urticae onto a novel host plant under initial presence or absence of a competing species, the congeneric mite T. ludeni.ResultsThe latter species unintentionally went extinct soon after the start of the experiment, but we nevertheless completed the experiment and found that the initial density of this ghost competitor positively affected the performance (i.e. fecundity) of the more successful species.This effect on T. urticae even lasted for at least 25 generations.DiscussionOur study supports the hypothesis that early experienced selection pressures can exert a persistent evolutionary signal on species’ performance in novel environments.

Section: Methodsmentioning

confidence: 99%

Performance in a novel environment subject to ghost competition

Bisschop

Bonte

et al. 2019

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“…The removed old plants may have contained mites or unhatched eggs, but we nevertheless chose this refreshment procedure to maintain relatively natural movement dynamics. It is for instance known that especially young fertilised females disperse more (Li & Margolies, 1993) and dispersive individuals may differ in their body condition or performance compared to sedentary individuals (Bonte et al, 2014;Dahirel et al, 2019). This refreshment procedure may have caused an extra competitive pressure if one species was more dispersive or delayed its dispersal for avoiding competition, but we preferred to design the experiment in a way that it resembled more the actual life strategy of spider mites (colonisation with few founders followed by rapid growth).…”

Section: Experimental Set-upmentioning

confidence: 99%

Performance in a novel environment subject to ghost competition

Bisschop

Bonte

et al. 2020

PeerJ

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Background A central tenet of the evolutionary theory of communities is that competition impacts evolutionary processes such as local adaptation. Species in a community exert a selection pressure on other species and may drive them to extinction. We know, however, very little about the influence of unsuccessful or ghost species on the evolutionary dynamics within the community. Methods Here we report the long-term influence of a ghost competitor on the performance of a more successful species using experimental evolution. We transferred the spider mite Tetranychus urticae onto a novel host plant under initial presence or absence of a competing species, the congeneric mite T. ludeni. Results The competitor species, T. ludeni, unintentionally went extinct soon after the start of the experiment, but we nevertheless completed the experiment and found that the early competitive pressure of this ghost competitor positively affected the performance (i.e., fecundity) of the surviving species, T. urticae. This effect on T. urticae lasted for at least 25 generations. Discussion Our study suggests that early experienced selection pressures can exert a persistent evolutionary signal on species’ performance in novel environments.

“…This phenotypic plasticity is usually expressed in body size, morphology, physiology, and behavior (Parsons et al 2011; Koeller, Mohn, and Etter 2000; Kamioka and Iwasa 2017; Le Galliard, Paquet, and Mugabo 2015; Woodworth et al 2017). Since dispersal is performed by a non-random subset of individuals from the population that share specific life history traits (Bonte et al 2012; Clobert et al 2012; Dahirel et al 2019) and physiology (Goossens et al 2020), connectivity changes will equally affect the sorting of phenotypes, and therefore phenotypic variation ( kind structure ) among patches. The spatial organization of phenotypes among and within patches then again has the potential to affect population dynamics.…”

Section: Introductionmentioning

confidence: 99%

“…We used the two-spotted spider mite Tetranychus urticae as a model to demonstrate how the spatial self-organization of phenotypes (i.e., the emerging kin and kind structure) equalizes metapopulation dynamics across connectedness levels (Urban et al 2020). The prerequisites for such a phenotypic self-organization are present: phenotypic variation in relation to local densities, stage and sex structure (Dahirel et al 2019; De Roissart, Wang, and Bonte 2015), density and kin-competition related dispersal (Van Petegem et al 2018; Fronhofer, Poethke, and Dieckmann 2015). Moreover, previous studies showed that this species’ phenotype-dependent dispersal maximizes fitness (Dahirel et al 2019; Bonte et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Individual heterogeneity and its importance for metapopulation dynamics

Masier

Dahirel

et al. 2020

Preprint

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Habitat fragmentation reduces the area of habitat patches and their connectedness in the landscape. It is well established that the level of connectedness impacts connectivity and metapopulation dynamics, and is therefore a central tenet in conservation biology. Connectedness equally generates sorting of phenotypes within the spatial network and therefore impacts local and regional eco-evolutionary dynamics. Paradoxically, recommendations for species conservation rely on principles derived from theory that neglects any individual phenotypic heterogenety and spatial organization.By creating experimental metapopulations using the model species Tetranychus urticae (two-spotted spider mite) with three levels of landscape connectedness and by regularly removing phenotypic structure in a subset of these populations, we tested the degree to which regional and local population dynamics are determined both by network connectedness and the phenotypic spatial organization.Our results show that some aspects of metapopulation dynamics can be attributed to the evolution of dispersal. More importantly, we find self-organization of phenotypic spatial structure to equalize the effects of reduced connectedness on metapopulation dynamics. These changes were all in the direction of improved metapopulation persistence. Contrary to expectations, the most connected local patches showed an overall reduced local population size, possibly originating from a faster depletion of resources from immigrants or transiting individuals.This experiment shows how metapopulation dynamics can significantly deviate from theoretical expectations if individual heterogeneity is considered, and more importantly that disruption of this phenotypic self-structuring may drive metapopulation dynamics towards higher risks of extinction.Significance StatementChanges in connectedness impact metapopulation dynamics but also the spatial organization of individual phenotypic heterogeneity. The extent to which metapopulation dynamics depend on this phenotypic structuring is unknown, despite the fact metapopulation theory is at the heart of conservation biology. By using experimental metapopulations and a randomization treatment, we demonstrate that the emerging spatial organization of individuals (both genetically and phenotypically) is a major driver of metapopulation dynamics. This spatial organization may be important as it may equalize all variation in metapopulation dynamics across a gradient of connectivity. This potentially rescuing effect stemming from the self-organization of phenotypes in metapopulations is of uttermost importance for conservation and translocation actions.