Dispersal syndromes in challenging environments: A cross‐species experiment

Dispersal is a central biological process tightly integrated into life-histories, morphology, physiology and behaviour. Such associations, or syndromes, are anticipated to impact the eco-evolutionary dynamics of spatially structured populations, and cascade into ecosystem processes. As for dispersal on its own, these syndromes are likely neither fixed nor random, but conditional on the experienced environment. We experimentally studied how dispersal propensity varies with individuals' phenotype and local environmental harshness using 15 species ranging from protists to vertebrates. We reveal a general phenotypic dispersal syndrome across studied species, with dispersers being larger, more active and having a marked locomotion-oriented morphology and a strengthening of the link between dispersal and some phenotypic traits with environmental harshness. Our proof-of-concept metacommunity model further reveals cascading effects of context-dependent syndromes on the local and regional organisation of functional diversity. Our study opens new avenues to advance our understanding of the functioning of spatially structured populations, communities and ecosystems. Keywords: context-dependent dispersal; dispersal strategy; distributed experiment; predation risk; resource limitatio

Eco-evolutionary feedbacks following changes in spatial connectedness

Humans are drastically changing the spatial configuration of habitats. The associated changes in habitat connectedness impose strong selection on dispersal, and dispersal related traits. Evolutionary responses do, however, strongly feedback on the metapopulation dynamics, by further constraining or improving connectivity and impacting local population and food web dynamics. Because these spatial eco-evolutionary interactions occur at contemporary time scales, unique evidence on its importance is especially emerging in the field of entomology as many insects have short generation times and a huge reproductive potential. We review the ecological feedbacks originating from the evolution of dispersal rate, dispersal syndromes and genetic diversity on metapopulation dynamics and range expansions. We thus close the eco-evolutionary loop for insect and arachnid spatial dynamics

Genetically diverse populations spread faster in benign but not in challenging environments

Population spread from a limited pool of founding propagules is at the basis of biological invasions. The size and genetic variation of these propagules eventually affect whether the invasion is successful or not. The inevitable bottleneck at introduction decreases genetic diversity, and therefore should affect population growth and spread. However, many heavily bottlenecked invasive populations have been successful in nature. Negative effects of a genetic bottleneck are typically considered to be relaxed in benign environments because of a release from stress. Despite its relevance to understand and predict invasions, empirical evidence on the role of genetic diversity in relation to habitat quality is largely lacking. We use the mite Tetranychus urticae Koch as a model to experimentally assess spread rate and size of genetically depleted inbred populations vs. enriched mixed populations. This was assessed in replicated linear patch systems consisting of benign (bean), challenging (tomato), or a gradient (bean to tomato) habitat. As expected, we found no effect of genetic diversity on population size in benign habitat but found that it increased population size in challenging habitat. However, we found that population spread rates were increased due to genetic diversity in the benign but not in the challenging habitat. Additionally, variance in spread was consistently higher in genetically poor populations and highest in the challenging habitat. Our experiment challenges the general view that a bottleneck in genetic variation decreases invasion success in challenging but not benign environments

Genetically diverse populations spread faster in benign but not in challenging environments

Population spread from a limited pool of founding propagules is at the basis of biological invasions. The size and genetic variation of these propagules eventually affect whether the invasion is successful or not. The inevitable bottleneck at introduction decreases genetic diversity, and therefore should affect population growth and spread. However, many heavily bottlenecked invasive populations have been successful in nature. Negative effects of a genetic bottleneck are typically considered to be relaxed in benign environments because of a release from stress. Despite its relevance to understand and predict invasions, empirical evidence on the role of genetic diversity in relation to habitat quality is largely lacking. We use the mite Tetranychus urticae Koch as a model to experimentally assess spread rate and size of genetically depleted inbred populations vs. enriched mixed populations. This was assessed in replicated linear patch systems consisting of benign (bean), challenging (tomato), or a gradient (bean to tomato) habitat. As expected, we found no effect of genetic diversity on population size in benign habitat but found that it increased population size in challenging habitat. However, we found that population spread rates were increased due to genetic diversity in the benign but not in the challenging habitat. Additionally, variance in spread was consistently higher in genetically poor populations and highest in the challenging habitat. Our experiment challenges the general view that a bottleneck in genetic variation decreases invasion success in challenging but not benign environments

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

International audienc

Impact of Microscopic Confirmation on Therapeutic Management of Pancreatic Cancer Patients: Lessons from an Italian Regional Tumor Registry

Background: Incidence of pancreatic cancer (PC) is increasing worldwide and is set to become the second leading cause of cancer-related death in 2040 with a poor 5-year overall survival (OS). The aim of this study was to analyze the impact of microscopic diagnosis of PC (MiDPC) on diagnostic–therapeutic management and outcome. Methods: The Veneto region (north-eastern Italy) has been covered by a cancer registry (CR) since 1987. Clinical and oncological data about all cases of PC in the Veneto region from 1987 were extracted from the Veneto CR database. Results: In 2018, 1340 incident cases of PC in the Veneto population were registered (4.1% of all malignant tumors), with an increasing trend in females and stable incidence in males. Five-year OS in patients with PC was 8%. The percentage of MiDPC increased from 44% in 2010 to 60% in 2018 (p = 0.001). MiDPC was higher among patients aged < 75 years old (84.4%) compared to those aged ≥75 years old (38.9%), p = 0.001. Between 2010 and 2018, a significant increase in biopsy on the primary neoplasm (24.9% vs. 13%, p < 0.001) was reported. Patients with MiDPC had higher 5-year survival than patients with no MiDPC (12.9% vs. 1.2%, p < 0.001). Conclusions: The implementation of MiDPC was essential to improve diagnostic–therapeutic pathways and consequently the survival of PC patients

Bottom-up and top-down control of dispersal across major organismal groups

Ecology and evolution unfold in spatially structured communities, where dispersal links dynamics across scales. Because dispersal is multicausal, identifying general drivers remains challenging. In a coordinated distributed experiment spanning organisms from protozoa to vertebrates, we tested whether two fundamental determinants of local dynamics, top-down and bottom-up control, generally explain active dispersal. We show that both factors consistently increased emigration rates and use metacommunity modelling to highlight consequences on local and regional dynamics

Dispersal syndromes in challenging environments: A cross‐species experiment

International audienceDispersal is a central biological process tightly integrated into life-histories, morphology, physiology and behaviour. Such associations, or syndromes, are anticipated to impact the eco-evolutionary dynamics of spatially structured populations, and cascade into ecosystem processes. As for dispersal on its own, these syndromes are likely neither fixed nor random, but conditional on the experienced environment. We experimentally studied how dispersal propensity varies with individuals' phenotype and local environmental harshness using 15 species ranging from protists to vertebrates. We reveal a general phenotypic dispersal syndrome across studied species, with dispersers being larger, more active and having a marked locomotion-oriented morphology and a strengthening of the link between dispersal and some phenotypic traits with environmental harshness