Biology subjects

Schtickzelle, N.

Publications and source records attributed to Schtickzelle, N..

6 recordsLinked to original sources

bioRxiv2025

Character displacement in shorebirds

Modification of phenotypic traits induced by character displacements allow species to coexist by reducing interspecific competition. This study explores if and how shorebirds partition feeding ressources by foraging at different water depths outside the breeding season. During this period, communities of up to dozen shorebird species coexist on suitable habitats at land-water interfaces. By video recording 22 species of migrating and wintering shorebirds in different sites, we show that their distribution according to the water height at which they forage is not random but follows a gradient of increasing water height according to increasing species body size. Species-specific beak and tarsus lengths are positively correlated with the water height at which the different species forage. Our data do not support a trade-off in investment between beak length and tarsus length in our study species set. Congeneric species that are expected to be morphologically and ecologically more similar forage at contrasted water heights. Altogether, our findings supports the idea of resource partitioning, and consequently of competition relaxation, by morphological and/or by behavioral character displacements.

evolutionary biology↗

bioRxiv2025

Beak elongation as key innovation in shorebird adaptive radiation

Adaptive radiations are often associated with phenotypic innovations that broaden ecological opportunity and bias subsequent ecological divergence. In shorebirds (Charadriiformes), variation in beak length has long been linked to resource partitioning, yet its role as a functional innovation has remained largely untested. Here, we integrate behavioural, morphological, and phylogenetic data from 29 Western Palearctic shorebird species to evaluate whether beak elongation fulfils key expectations of a candidate innovation by being repeatedly associated with ecological and functional transitions. Species with longer than expected beaks relative to body size consistently exhibit distinct locomotor, prey-capture, and food-transport strategies. These integrated morphological-behavioural syndromes recur across independent lineages, suggesting convergent evolution driven by shared ecological constraints. Phylogenetic analyses indicate multiple independent origins of relative beak elongation, supporting its role as a repeated evolutionary solution. Together, our results support a functionally integrated view of adaptation, in which coordinated changes in morphology, sensory investment, and behaviour facilitate access to alternative foraging microhabitats and enable repeated ecological transitions within shorebirds. More broadly, this study provides a testable framework for identifying candidate innovations based on replicated trait-niche associations. O_FIG O_LINKSMALLFIG WIDTH=198 HEIGHT=200 SRC="FIGDIR/small/671984v2_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@185f912org.highwire.dtl.DTLVardef@a33baforg.highwire.dtl.DTLVardef@a37b35org.highwire.dtl.DTLVardef@ee0831_HPS_FORMAT_FIGEXP M_FIG C_FIG

evolutionary biology↗

bioRxiv2021

Dispersal syndromes affect ecosystem functioning in ciliate microcosms

Dispersal is a key process mediating ecological and evolutionary dynamics. Its effects on metapopulations dynamics, population genetics or species range distribution can depend on phenotypic differences between dispersing and non-dispersing individuals (i.e., dispersal syndromes). However, scaling up to the importance of dispersal syndromes for meta-ecosystems have rarely been considered, despite intraspecific phenotypic variability is now recognised as an important factor mediating ecosystem functioning. In this study, we characterised the intraspecific variability of dispersal syndromes in twenty isolated genotypes of the ciliate Tetrahymena thermophila to test their consequences for biomass productivity in communities composed of five Tetrahymena species. To do so, dispersers and residents of each genotype were introduced, each separately, in ciliate communities composed of four other competing species of the genus Tetrahymena to investigate the effects of dispersal syndromes. We found that introducing dispersers led to a lower biomass compared to introducing residents. This effect was highly consistent across the twenty T. thermophila genotypes despite their marked differences of dispersal syndromes. Finally, we found a strong genotypic effect on biomass production, confirming that intraspecific variability in general affected ecosystem functions in our system. Our study shows that intraspecific variability and the existence of dispersal syndromes can impact the functioning of spatially structured ecosystems in a consistent and therefore predictable way.

ecology↗

bioRxiv2019

Anthropogenic disturbance drives dispersal syndromes, demography, and gene flow in spatially structured amphibian populations

There is growing evidence that anthropogenic landscapes can strongly influence the evolution of dispersal, particularly through fragmentation, and may drive organisms into an evolutionary trap by suppressing dispersal. However, the influence on dispersal evolution of anthropogenic variation in habitat patch turnover has so far been largely overlooked. In this study, we examined how human-driven variation in patch persistence affects dispersal rates and distances, determines dispersal-related phenotypic specialization, and drives neutral genetic structure in spatially structured populations. We addressed this issue in an amphibian, Bombina variegata, using an integrative approach combining capture-recapture modeling, demographic simulation, common garden experiments, and population genetics. B. variegata reproduces in small ponds that occur either in habitat patches that are persistent (i.e. several decades or more), located in riverine environments with negligible human activity, or in patches that are highly temporary (i.e. a few years), created by logging operations in intensively harvested woodland. Our capture-recapture models revealed that natal and breeding dispersal rates and distances were drastically higher in spatially structured populations (SSPs) in logging environments than in riverine SSPs. Population simulations additionally showed that dispersal costs and benefits drive the fate of logging SSPs, which cannot persist without dispersal. The common garden experiments revealed that toadlets reared in laboratory conditions have morphological and behavioral specialization that depends on their habitat of origin. Toadlets from logging SSPs were found to have higher boldness and exploration propensity than those from riverine SSPs, indicating transgenerationally transmitted dispersal syndromes. We also found contrasting patterns of neutral genetic diversity and gene flow in riverine and logging SSPs, with genetic diversity and effective population size considerably higher in logging than in riverine SSPs. In parallel, intra-patch inbreeding and relatedness levels were lower in logging SSPs. Controlling for the effect of genetic drift and landscape connectivity, gene flow was found to be higher in logging than in riverine SSPs. Taken together, these results indicate that anthropogenic variation in habitat patch turnover may have an effect at least as important as landscape fragmentation on dispersal evolution and the long-term viability and genetic structure of wild populations.

ecology↗

bioRxiv2019

Transgenerational dispersal plasticity and its fitness consequences are under genetic control

Phenotypic plasticity, the ability of one genotype to produce different phenotypes in different environments, plays a central role in species response to environmental changes. Transgenerational plasticity (TGP) allows the transmission of this environmentally-induced phenotypic variation across generations, and can influence adaptation. To date, the genetic control of TGP, its long-term stability, and its potential costs remain largely unknown, mostly because empirical demonstrations of TGP across many generations in several genetic backgrounds are scarce. Here, we examined how genotype determines the TGP of dispersal, a fundamental process in ecology and evolution. We used an experimental approach involving ~200 clonal generations in a model-species of ciliate to determine if and how TGP influences the expression of dispersal-related traits in several genotypes. Our results show that morphological and movement traits associated with dispersal are plastic, and that these modifications are inherited over at least 35 generations. We also highlight that genotype modulates the fitness costs and benefits associated with plastic dispersal strategies. Our study suggests that genotype-dependent TGP could play a critical role in eco-evolutionary dynamics as dispersal determines gene flow and the long-term persistence of natural populations. More generally, it outlines the tremendous importance that genotype-dependent TGP could have in the ability of organisms to cope with current and future environmental changes.\n\nSignificanceThe genetic control of the transgenerational plasticity is still poorly understood despite its critical role in species responses to environmental changes. We examined how genotype determines transgenerational plasticity of a complex trait (i.e., dispersal) in a model-species of ciliate across ~200 clonal generations. Our results provide evidence that plastic phenotypic variation linked to dispersal is stably inherited over tens of generations and that cell genotype modulates the expression and fitness cost of transgenerational plasticity.

evolutionary biology↗

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↗