Biology subjects

Masier, S.

Publications and source records attributed to Masier, S..

6 recordsLinked to original sources

bioRxiv2024

On the evolution of dispersal strategies under the costs of acquisition of private and social information

Dispersal between patches of suitable habitat is a key behaviour for the survival of animal populations and is impacted by rapid environmental changes. Animals must cope with several costs related to the dispersal process, such as expenses in energy for acquiring information or increased mortality risks. There is a growing interest in studying how the costs of acquisition of information influence the dispersal be- haviour of species, and particularly how the use of social and private information can shape this behaviour over multiple generations. Current models of dispersal rarely incorporate both sources of information, and there is specifically a lack of modelling studies taking into account costs of acquisition for private and social information. We develop an agent-based model simulating a population of butterflies with genetic factors linked to the acquisition of both types of information and their associated reproductive costs. We show that different costs, environmental variability conditions and sensory abilities result in various dispersal behaviours and have an impact on the fitness of the population. In stable environments, low-cost information is used by a varying proportion of agents to disperse, but when the cost rises lightly, all agents stay uninformed. In highly variable environments, the same trend is observed, but agents rely on information even if the cost of acquisition increases up to twice compared to stable environments as it provides an evolutionary advantage. Agents with a limited perceptual range use both information sources equally in variable environments, and those with a bigger perceptual range rely exclusively on private information to take dispersal decisions, except at free cost of acquisition. Globally, the use of information induces a higher fitness for the population in stable environments if costs of acquisition are free or very low. In variable environmental conditions, the highest fitness is maintained with a limited perceptual range when the total cost rises up to twice the value found for stable environments. With a bigger perceptual range, the highest fitness is maintained for the whole range of total costs studied.

ecology↗

bioRxiv2020

Individual heterogeneity and its importance for metapopulation dynamics.

Landscape connectedness shapes the exchange of individuals among patches, and hence metapopulation connectivity and dynamics. Connectedness, and its resulting effects on connectivity are therefore rightfully central in conservation biology. However, besides determining demographic fluxes of individuals between patches, connectedness also generates phenotypic sorting and thus impacts local and regional eco-evolutionary dynamics. Despite the central role of connectedness, its effects on individual phenotypic heterogeneity and spatial organization are so far neglected in theory and applications. Through experimental metapopulations of 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 how regional and local population dynamics are determined both by network connectedness and phenotypic spatial organization. We find that the self-organizing phenotypic spatial structure increases local equilibrium population sizes and variability. It in contrast dampens the effects of imposed connectedness differences on population sizes and is therefore anticipated to improve metapopulation persistence. Contrary to theoretical expectations, the most locally connected patches within the network 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 due to individual heterogeneity. This potential rescue effect stemming from phenotypical self-organization in space is a key point to consider for conservation actions, especially based on translocations.

ecology↗

bioRxiv2020

Evolutionary history determines population spread rate in a stochastic, rather than in a deterministic way

Fragmentation of natural landscapes results in habitat and connectedness loss, making it one of the most impactful avenues of anthropogenic environmental degradation. Populations living in a fragmented landscape can adapt to this context, as witnessed in changing dispersal strategies, levels of local adaptation and changing life-history traits. This evolution, however, can have ecological consequences beyond a fragmented range. Since invasive dynamics are driven by the same traits affected by fragmentation, the question arises whether fragmented populations evolve to be successful invaders. In this study we assess population spread during three generations of two-spotted spider mite (Tetranychus urticae) population in a replicated experiment. Experimental populations evolved independently in replicated experimental metapopulations differing only in the level of habitat connectedness as determined by the inter-patch distance. We find that habitat connectedness did not meaningfully explain variation in population spread rate. Rather, variation within experimental populations that shared the same level of connectedness during evolution was larger than the one across these levels. Therefore, we conclude that experimental populations evolved different population spread capacities as a result of their specific evolutionary background independent but of the connectedness of the landscape. While population spread capacities may be strongly affected by aspects of a populations evolutionary history, predicting it from identifiable aspects of the evolutionary history may be hard to achieve.

ecology↗

bioRxiv2019

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

Dispersing individuals are expected to encounter costs during transfer and in the novel environment, and may also have experienced stress in their natal patch. Given this, a non-random subset of the population should engage in dispersal and eventually show divergent stress-related responses towards new conditions. Dispersal allows escape from stress, but is equally subjecting individuals to it.\n\nPhysiological shifts expressed in the metabolome form a major part of responses to stress exposure and are expected to be associated with the dispersal phenotype, thereby shaping physiological dispersal syndromes. We analyzed how metabolic profiles and life-history traits varied between dispersers and residents of the model two-spotted spider mite Tetranychus urticae, and whether and how these syndromes varied with exposure to a stressful new host plant (tomato). Regardless of the effect of host plant, we found a physiological dispersal syndrome where, relative to philopatric individuals, dispersers were characterized by lower leaf consumption rates and a lower concentration of several amino acids, indicating a potential dispersal-foraging trade-off. As a possible consequence of this lower food intake, dispersers also showed a lower reproductive performance. Responses to tomato exposure were consistent with this plant being a stressor for Tetranychus urticae, including reduced fecundity and reduced feeding by mites. Tomato-exposed mites laid larger eggs, which can be interpreted as a plastic response to food stress, increasing the likelihood of survival to maturity. Contrary to what could be expected from the costs of dispersal and stress resistance and from previous meta-population level studies, there was no interaction between dispersal status and host plant for any of the examined traits, indicating that the impacts of a new stressful host plant are equally incurred by residents and dispersers.\n\nWe thus provide novel insights in the processes that shape dispersal and the putative feedbacks on ecological dynamics in spatially structured populations.

ecology↗

bioRxiv2018

Unexpected evolution following connectedness loss

Dispersal evolution impacts the fluxes of individuals and hence, connectivity in metapopulations. Connectivity is therefore decoupled from the structural connectedness of the patches within the spatial network. Because of demographic feedbacks, local selection can additionally steer the evolution of other life history traits. We investigated how different levels of connectedness affect dispersal and life history evolution by varying the interpatch distance in replicated experimental metapopulations of the two-spotted spider. We implemented a shuffling treatment to separate local- and metapopulation-level selection.\n\nWith lower metapopulation connectedness, an increased starvation resistance and delayed dispersal evolved. Intrinsic growth rates evolved at the local level by transgenerational plasticity or epigenetic processes. Changes in patch connectedness thus induce the genetic and non-genetic evolution of dispersal costs and demographic traits at both the local and metapopulation level. These trait changes are anticipated to impact metapopulations eco-evolutionary dynamics, and hence, the persistence and performance of spatially structured populations.

ecology↗

bioRxiv2017

Bottom-up and top-down control of dispersal across major organismal groups: a coordinated distributed experiment

Organisms rarely experience a homogeneous environment. Rather, ecological and evolutionary dynamics unfold in spatially structured and fragmented landscapes, with dispersal as the central process linking these dynamics across spatial scales. Because dispersal is a multi-causal and highly plastic life-history trait, finding general drivers that are of importance across species is challenging but highly relevant for ecological forecasting.\n\nWe here tested whether two fundamental ecological forces and main determinants of local population dynamics, top-down and bottom-up control, generally explain dispersal in spatially structured communities. In a coordinated distributed experiment spanning a wide range of actively dispersing organisms, from protozoa to vertebrates, we show that bottom-up control, that is resource limitation, consistently increased dispersal. While top-down control, that is predation risk, was an equally important dispersal driver as bottom-up control, its effect depended on prey and predator space use and whether dispersal occurred on land, in water or in the air: species that routinely use more space than their predators showed increased dispersal in response to predation, specifically in aquatic environments. After establishing these general causes of dispersal, we used a metacommunity model to show that bottom-up and top-down control of dispersal has important consequences for local population fluctuations as well as cascading effects on regional metacommunity dynamics. Context-dependent dispersal reduced local population fluctuations and desynchronized dynamics between communities, two effects that increase population and community stability.\n\nOur study provides unprecedented insights into the generality of the positive resource dependency of dispersal as well as a robust experimental test of current theory predicting that predator-induced dispersal is modulated by prey and predator space use. Our experimental and theoretical work highlights the critical importance of the multi-causal nature of dispersal as well as its cascading effects on regional community dynamics, which are specifically relevant to ecological forecasting.

ecology↗