Biology subjects

Parmentier, T.

Publications and source records attributed to Parmentier, T..

6 recordsLinked to original sources

bioRxiv2023

A successional shift enhances stability in ant symbiont communities

Throughout succession, communities undergo structural shifts, which can alter the relative abundances of species and how they interact. It is frequently asserted that these alterations beget stability, i.e. that succession selects for communities better able to resist perturbations. Yet, whether and how alterations of network structure affects stability during succession in complex communities is rarely studied in natural ecosystems. Here, we explore how network attributes influence stability of different successional stages of a natural network: symbiotic arthropod communities forming food webs inside red wood ant nests. We conducted extensive field sampling to compare the composition of the symbiont community across 51 host nests of varying age, representing different succession stages. We recorded abundance of 16 functional groups of symbionts spanning different specialization and trophic levels. Joint species distribution modelling indicated nest age as the driver of the compositional shifts: symbiont communities in old nests contained a greater proportion of specialists and more even species abundance distributions. We then reconstructed community matrices and showed that this enhanced evenness lead to an augmented food web stability of the symbiont communities in older nests. Overall, this study demonstrates that succession begets stability in a natural ecological network by making the community more even.

ecology↗

bioRxiv2023

Co-habiting ants and silverfish display a converging feeding ecology

O_LISpecies from a great number of animal taxa have specialized to living with social hosts. Depending on their level of specialization, these symbiotic animals are characterized by distinct behavioural, chemical, and morphological traits that enable close heterospecific interactions. Despite its functional importance, our understanding of the feeding ecology of specialized animals living with social hosts remains limited. C_LIO_LIIn this study, we examined how host specialization of silverfish co-habiting with ants affects several components of their feeding ecology. We combined stable isotope profiling, feeding assays, phylogenetic reconstruction, and microbial community characterization of the Neoasterolepisma silverfish genus and a wider nicoletiid and lepismatid silverfish panel where divergent myrmecophilous lifestyles are observed. C_LIO_LIStable isotope profiling ({delta}13C and {delta}15N) showed that the isotopic niches (proxy for trophic niches) of granivorous Messor ants and Messor-specialized Neoasterolepisma exhibit a remarkable overlap within an ant nest. Trophic experiments and gut dissections further supported that these specialized Neoasterolepisma silverfish transitioned to a diet that includes plant seeds. In contrast, the isotopic niches of generalist Neoasterolepisma silverfish and generalist nicoletiid silverfish were clearly different from their ant hosts within the shared nest environment. C_LIO_LIThe impact of the myrmecophilous lifestyle on feeding ecology was also evident in the internal silverfish microbiome. Compared to generalists, Messor-specialists exhibited a higher bacterial density and a higher proportion of heterofermentative lactic acid bacteria. Moreover, the nest environment explained the infection profile (or the 16S rRNA genotypes) of Weissella bacteria in Messor-specialized silverfish and the ant hosts. C_LIO_LITogether, we show that social hosts are important determinants for the feeding ecology of symbiotic animals, and can induce diet convergence. C_LI

ecology↗

bioRxiv2022

Differential transport of a guild of mutualistic root aphids by the ant Lasius flavus

Mutually beneficial associations are widespread in ecological networks. They are typically assembled as multispecies guilds of symbionts that compete for one or more host species. The ant Lasius flavus engages in an intriguing and obligate mutualistic association with a community of aphids that are cultivated on plant roots in its nests. The ant displays a repertoire of amicable behaviours towards the aphids, including their transport. I examined whether L. flavus preferentially carried some of the root aphids. Using a no-choice and a choice experiment, I comparatively analysed the transport rate of five obligate and one loosely associated species back to the ant nest and used the transport rate of the ant larvae as a reference. All associated root aphids were carried back to the nest, but in a clear preferential hierarchy. Geoica utricularia, Forda Formicaria and Trama rara were rapidly transported, but slower than the own larvae. Tetraneura ulmi and Geoica setulosa were collected at a moderate rate and the loosely associated Aploneura lentisci was slowly retrieved. In contrast, different species of unassociated aphids were not transported and even provoked aggressive behaviour in L. flavus. This study revealed that co-occurring symbionts may induce different degrees of host attraction, which ultimately may affect the coexistence and assembly of ant-symbiont communities.

ecology↗

bioRxiv2022

Human Cerebral Spheroids Undergo Activity Dependent Changes In Cellular Composition And MicroRNA Expression

Activity-induced neurogenesis has been extensively studied in rodents but the lack of ante mortem accessibility to human brain at the cellular and molecular levels limits studies of the process in humans. Using cerebral spheroids derived from human induced pluripotent stem cells (iPSCs), we investigated the effects of increased neuronal activity on neurogenesis. Our studies demonstrate that increasing neuronal activity with 4-aminopyridine in 3-month-old cerebral spheroids is associated with increases in the numbers of new neurons and decreases in the population of new glial cells. We also observed a significant decrease in the expression of miR-135a, which has previously been shown to be decreased in exercise-induced neurogenesis. Predicted targets of miR-135a include key participants in the SMAD2/3 and BDNF pathways. Together, our results suggest that iPSC-derived cerebral spheroids are an attractive model to study some aspects of activity-induced neurogenesis.

neuroscience↗

bioRxiv2021

Honest cues contribute to male choice for female guarding in a herbivorous spider mite.

Mate choice is a wide-spread phenomenon with important effects on ecological and evolutionary dynamics of successive generations. Increasing evidence shows that males can choose females if females vary in quality and these mating choices can strongly impact fitness. In the herbivorous spider mite Tetranychus urticae males engage in precopulatory mate guarding of quiescent females, and it is known that females vary in their time to sexual maturity and fecundity. However, our understanding of how males maximize their reproductive success and which female phenotypic traits are important cues for their mating decisions are still limited. In many arthropod species, female body size and pheromones are well known proxies for fecundity. These traits--and thus possibly male mating decisions--are however sensitive to environmental (dietary) stress. By allowing males to freely choose amongst many (synchronized) females in a controlled semi natural environment, we found that guarded females have a higher fecundity and are closer to sexual maturity than non-guarded females. Despite the fact that female body size was positively correlated with fecundity and significantly influenced by the environment, males did not discriminate on body size nor did we find evidence that they used other cues like cuticular pheromones or copying behavior (social cues). In conclusion we were able to show male mate preference for females that are closer to sexual maturity and have higher fecundity, but we were unable to identify the female traits that signal this information

animal behavior and cognition↗

bioRxiv2019

Unravelling ant-symbiont network topology across Europe

Long-term associations between different species are key drivers in community composition in all ecosystems. Understanding the ecological and evolutionary drivers of these symbiotic associations is challenging because of the diversity of species and interaction types hosted in natural ecological networks. Here, we compiled the most complete database on natural ant-symbiont networks in Europe to identify the drivers of bipartite network topology. These ant-symbiont networks host an unrivalled diversity of symbiotic associations across the entire mutualism-antagonism continuum, of which the most diverse types of symbionts are (1) trophobionts: mutualistic aphids and scale insects (2) myrmecophiles: commensalistic and parasitic arthropods, and (3) social parasites: parasitic ant species. These diverse ant-symbiont networks provide a unique opportunity to tease apart ecological and evolutionary drivers. To do so, we dissected network topology and asked what determines host specificity and which host factors drive symbiont species richness and facilitate host switching for the different types of symbionts. We found an unexpectedly high number of 701 obligate symbionts associated with European ants. Symbiont type explained host specificity and the average relatedness of the targeted host species. Social parasites were associated with few, but phylogenetically highly related hosts, whereas trophobionts and myrmecophiles interacted with a higher number of hosts across a wider taxonomic distribution. Colony size, host range and habitat type predicted total symbiont richness, where ants hosts with larger colony size or larger distribution range contained more symbiont species. However, we found that different sets of host factors affected diversity in the different types of symbionts. Ecological factors, such as colony size, host range and niche width predominantly drive myrmecophile species richness, whereas evolutionary factors, such as host phylogeny and biogeography, mainly determine richness of mutualistic trophobionts and social parasites. Lastly, we found that hosts with a common biogeographic history support a more similar community of symbionts. Phylogenetic related hosts also shared more trophobionts and social parasites, but not myrmecophiles. Taken together, these results suggest that ecological and evolutionary processes drive host specificity and symbiont richness in large-scale ant-symbiont networks, but these drivers may shift in importance depending on the type of symbiosis. Our findings highlight the potential of well-characterized bipartite networks composed of different types of symbioses to identify candidate processes driving community composition.

ecology↗