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Id | Title * | Authors * ▲ | Abstract * | Picture * | Thematic fields * | Recommender | Reviewers | Submission date | |
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20 Sep 2018
![]() When higher carrying capacities lead to faster propagationMarjorie Haond, Thibaut Morel-Journel, Eric Lombaert, Elodie Vercken, Ludovic Mailleret & Lionel Roques https://doi.org/10.1101/307322When the dispersal of the many outruns the dispersal of the fewRecommended by Matthieu BarbierAre biological invasions driven by a few pioneers, running ahead of their conspecifics? Or are these pioneers constantly being caught up by, and folded into, the larger flux of propagules from the established populations behind them? References [1] Levins, R., & Culver, D. (1971). Regional Coexistence of Species and Competition between Rare Species. Proceedings of the National Academy of Sciences, 68(6), 1246–1248. doi: 10.1073/pnas.68.6.1246 | When higher carrying capacities lead to faster propagation | Marjorie Haond, Thibaut Morel-Journel, Eric Lombaert, Elodie Vercken, Ludovic Mailleret & Lionel Roques | <p>This preprint has been reviewed and recommended by Peer Community In Ecology (https://dx.doi.org/10.24072/pci.ecology.100004). Finding general patterns in the expansion of natural populations is a major challenge in ecology and invasion biology... | ![]() | Biological invasions, Colonization, Dispersal & Migration, Experimental ecology, Population ecology, Spatial ecology, Metacommunities & Metapopulations, Theoretical ecology | Matthieu Barbier | Yuval Zelnik | 2018-04-25 10:18:48 | View |
20 Sep 2024
![]() Body mass change over winter is consistently sex-specific across roe deer (Capreolus capreolus) populationsMark Hewison, Nadège Bonnot, Jean-Michel Gaillard, Petter Kjellander, Jean-François Lemaitre, Nicolas Morellet & Maryline Pellerin https://doi.org/10.1101/2022.09.09.507329Is it sexual mass dimorphism season?Recommended by Denis Réale based on reviews by Patrick Bergeron, Philip McLoughlin and Achaz von HardenbergPolygyny is assumed to have led to the evolution of strong sexual size dimorphism (SSD) in mammals, males often being heavier or showing more developed armaments than females (Weckerly 1998; Loison et al. 1999; Pérez‐Barbería et al. 2002). SSD generally increases with the degree of polygyny of the species. However, the degree of SSD, and particularly of sexual mass dimorphism, is not fixed for each species, and differences exist between populations (Blanckenhorn et al. 2006; Cox & Calsbeek 2010) or even between seasons within populations (Rughetti & Festa‐Bianchet 2011). In this study, Hewison et al. propose that studying seasonal variation in sexual mass dimorphism and how this can be affected by winter harshness and latitude allows us to better assess the energetic costs associated with the eco-evolutionary constraints acting on each sex. To achieve their goal, Hewison et al. use a formidable, long-term dataset of over 7,000 individuals, in five roe deer populations (Capreolus capreolus), from south-west France and Sweden. According to the authors, sexual mass dimorphism should be at its lowest in early spring in this species due to a stronger trade-off between antler growth and body weight maintenance in males over winter than in females. Furthermore, harsher conditions, varying both in time and space (i.e., Sweden vs. France), should increase winter weight loss, and thus, mass change differences between the sexes should be stronger and show more variation in Sweden than in France.
References Blanckenhorn, W. U., Stillwell, R. C., Young, K. A., Fox, C. W., & Ashton, K. G. (2006). When Rensch meets Bergmann: does sexual size dimorphism change systematically with latitude? Evolution, 60(10), 2004-2011. https://doi.org/10.1554/06-110.1 | Body mass change over winter is consistently sex-specific across roe deer (*Capreolus capreolus*) populations | Mark Hewison, Nadège Bonnot, Jean-Michel Gaillard, Petter Kjellander, Jean-François Lemaitre, Nicolas Morellet & Maryline Pellerin | <p>In most polygynous vertebrates, males must allocate energy to growing secondary sexual characteristics, such as ornaments or weapons, that they require to attract and defend potential mates, impacting body condition and potentially entailing fi... | ![]() | Behaviour & Ethology, Life history | Denis Réale | 2022-09-16 15:41:53 | View | |
07 Feb 2025
![]() In defense of the original Type I functional response: The frequency and population-dynamic effects of feeding on multiple prey at a timeMark Novak, Kyle Edward Coblentz, John P DeLong https://doi.org/10.1101/2024.05.14.594210Revising behavioural assumptions leads to a new appreciation of an old functional response modelRecommended by Frédéric BarraquandThe functional response, describing the relation between predator intake rate and prey density, is a pivotal concept to understand foraging behaviour and its consequences for community dynamics. Holling (1959a) introduced three types of functional responses according to their shapes, labelled I, II and III. The type II, also known as the disc equation (Holling 1959b), has become popular among empiricists and theoreticians alike, due to its ability to describe predator intake saturation. The type III is often used to represent predator switching to other prey species when main prey density is low. Although theoretical works identify the linear functional response used in Lotka-Volterra models as a type I, Holling (1959a)’s type I model actually envisioned that at some threshold prey density, the linear increase in predator intake with prey density would give way to an upper predator intake limit, so that Holling’s type I has a rectilinear shape, with an angle joining straight lines. Ecology students can actually see this rectilinear shape reproduced in some texbooks, although not in textbook dynamical models, as they usually transition from Lotka-Volterra models to models with type II response. To many, the rectilinear shape of the original type I looks like a historical curiosity: the type II functional response accounts for intake rate saturation with a more convenient smooth function. Novak et al. (2025) turn this preconception on its head by first pedagogically showing that Holling’s original type I model can be obtained as a limit case of a variant of the celebrated type II model. The derivation follows up earlier work by Sjöberg (1980), which might be unfamiliar to readers outside aquatic ecology. The often untold assumption of the type II functional response model is that searching and handling prey are two exclusive behavioural processes, with predators that can only handle one prey item at a time. Allowing for several prey items to be handled at once while searching, until the predator reaches n prey items, the original type I functional response emerges as a limit case of the « multiprey » functional response as n goes to infinity. Interestingly, the multiprey response looks a lot like the original type I for large yet doable n. Novak et al. (2025) then proceed to look for the prevalence of such multiprey functional response shapes in a large database of functional responses (Uiterwaal et al. 2022). Combining linear type I and multiprey models (the asymptote may not always be visible), they find support for this revised type I hypothesis in about one-third of the cases. Although the type II and III models are still well supported by data, the results do suggest that linearity at low prey density may well be more frequent than one thinks. They complement this analysis by showing that larger predators relative to their prey tend to have larger n in the multiprey response. It is consistent with the hypothesis that the bigger you are relative to your prey, the more prey items you can handle at once. Finally, Novak et al. (2025) investigate the consequences of the multiprey model for community dynamics. They find overall a richer dynamical behaviour than the Lotka-Volterra type I and common parameterizations of the type II, suggesting that observed linearity in some range of prey density does not necessarily translate in simpler dynamical behaviour. Novak et al. (2025) provide here a convincing and pedagogical study showing how seemingly benign behavioural assumptions can in fact profoundly alter the perceived relevance of community dynamics models. As they conclude, their analyses have lessons for future empirical functional response work, which should not necessarily dismiss the type I model and consider perhaps variants to the classical type II and III, as well as for future theoretical analyses, which could generalize this model to multiple prey species, or relax other behavioural assumptions. References Holling, C. S. (1959a). The components of predation as revealed by a study of small-mammal predation of the European Pine Sawfly. The Canadian Entomologist, 91(5), 293-320. https://doi.org/10.4039/Ent91293-5 Holling, C. S. (1959b). Some characteristics of simple types of predation and parasitism. The Canadian Entomologist, 91(7), 385-398. https://doi.org/10.4039/Ent91385-7 Novak, M., Coblentz, K. E., & DeLong, J. P (2025). In defense of the original Type I functional response: The frequency and population-dynamic effects of feeding on multiple prey at a time. bioRxiv, ver.4 peer-reviewed and recommended by PCI Ecology https://doi.org/10.1101/2024.05.14.594210 Sjöberg, S. (1980). Zooplankton feeding and queueing theory. Ecological Modelling, 10(3-4), 215-225. https://doi.org/10.1016/0304-3800(80)90060-5 Uiterwaal, S. F., Lagerstrom, I. T., Lyon, S. R., & DeLong, J. P. (2022). FoRAGE database: A compilation of functional responses for consumers and parasitoids. Ecology, 103(7), e3706. https://doi.org/10.1002/ecy.3706 | In defense of the original Type I functional response: The frequency and population-dynamic effects of feeding on multiple prey at a time | Mark Novak, Kyle Edward Coblentz, John P DeLong | <p>Ecologists differ in the degree to which they consider the linear Type I functional response to be an unrealistic versus sufficient representation of predator feeding rates. Empiricists tend to consider it unsuitably non-mechanistic and theoret... | ![]() | Coexistence, Community ecology, Food webs, Foraging, Population ecology, Theoretical ecology | Frédéric Barraquand | 2024-05-21 03:44:00 | View | |
13 May 2024
![]() Getting More by Asking for Less: Linking Species Interactions to Species Co-Distributions in MetacommunitiesMatthieu Barbier, Guy Bunin, Mathew A. Leibold https://doi.org/10.1101/2023.06.04.543606Beyond pairwise species interactions: coarser inference of their joined effects is more relevantRecommended by François MunozBarbier et al. (2024) investigated the dynamics of species abundances depending on their ecological niche (abiotic component) and on (numerous) competitive interactions. In line with previous evidence and expectations (Barbier et al. 2018), the authors show that it is possible to robustly infer the mean and variance of interaction coefficients from species co-distributions, while it is not possible to infer the individual coefficient values. The authors devised a simulation framework representing multispecies dynamics in an heterogeneous environmental context (2D grid landscape). They used a Lotka-Volterra framework involving pairwise interaction coefficients and species-specific carrying capacities. These capacities depend on how well the species niche matches the local environmental conditions, through a Gaussian function of the distance of the species niche centers to the local environmental values. They considered two contrasted scenarios denoted as « Environmental tracking » and « Dispersal limited ». In the latter case, species are initially seeded over the environmental grid and cannot disperse to other cells, while in the former case they can disperse and possibly be more performant in other cells. The direct effects of species on one another are encoded in an interaction matrix A, and the authors further considered net interactions depending on the inverse of the matrix of direct interactions (Zelnik et al., 2024). The net effects are context-dependent, i.e., it involves the environment-dependent biotic capacities, even through the interaction terms can be defined between species as independent from local environment. The results presented here underline that the outcome of many individual competitive interactions can only be understood in terms of macroscopic properties. In essence, the results here echoe the mean field theories that investigate the dynamics of average ecological properties instead of the microscopic components (e.g., McKane et al. 2000). In a philosophical perspective, community ecology has long struggled with analyzing and inferring local determinants of species coexistence from species co-occurrence patterns, so that it was claimed that no universal laws can be derived in the discipline (Lawton 1999). Using different and complementary methods and perspectives, recent research has also shown that species assembly parameter values cannot be unambiguously inferred from species co-occurrences only, even in simple designs where an equilibrium can be reached (Poggiato et al. 2021). Although the roles of high-order competitive interactions and intransivity can lead to species coexistence, the simple view of a single loop of competitive interactions is easily challenged when further interactions and complexity is added (Gallien et al. 2024). But should we put so much emphasis on inferring individual interaction coefficients? In a quest to understand the emerging properties of elementary processes, ecological theory could go forward with a more macroscopic analysis and understanding of species coexistence in many communities. The authors referred several times to an interesting paper from Schaffer (1981), entitled « Ecological abstraction: the consequences of reduced dimensionality in ecological models ». It proposes that estimating individual species competition coefficients is not possible, but that competition can be assessed at the coarser level of organisation, i.e., between ecological guilds. This idea implies that the dimensionality of the competition equations should be greatly reduced to become tractable in practice. Taking together this claim with the results of the present Barbier et al. (2024) paper, it becomes clearer that the nature of competitive interactions can be addressed through « abstracted » quantities, as those of guilds or the moments of the individual competition coefficients (here the average and the standard deviation). Therefore the scope of Barbier et al. (2024) framework goes beyond statistical issues in parameter inference, but question the way we must think and represent the numerous competitive interactions in a simplified and robust way. References Barbier, Matthieu, Jean-François Arnoldi, Guy Bunin, et Michel Loreau. 2018. « Generic assembly patterns in complex ecological communities ». Proceedings of the National Academy of Sciences 115 (9): 2156‑61. https://doi.org/10.1073/pnas.1710352115 | Getting More by Asking for Less: Linking Species Interactions to Species Co-Distributions in Metacommunities | Matthieu Barbier, Guy Bunin, Mathew A. Leibold | <p>AbstractOne of the more difficult challenges in community ecology is inferring species interactions on the basis of patterns in the spatial distribution of organisms. At its core, the problem is that distributional patterns reflect the ‘realize... | ![]() | Biogeography, Community ecology, Competition, Spatial ecology, Metacommunities & Metapopulations, Species distributions, Statistical ecology, Theoretical ecology | François Munoz | 2023-10-21 14:14:16 | View | |
03 Apr 2020
![]() A macro-ecological approach to predators' functional responseMatthieu Barbier, Laurie Wojcik, Michel Loreau https://doi.org/10.1101/832220A meta-analysis to infer generic predator functional responseRecommended by Samir Simon Suweis based on reviews by Ludek Berec and gyorgy barabasSpecies interactions are classically derived from the law of mass action: the probability that, for example, a predation event occurs is proportional to the product of the density of the prey and predator species. In order to describe how predator and prey species populations grow, is then necessary to introduce functional response, describing the intake rate of a consumer as a function of food (e.g. prey) density. References [1] Volterra, V. (1928). Variations and Fluctuations of the Number of Individuals in Animal Species living together. ICES Journal of Marine Science, 3(1), 3–51. doi: 10.1093/icesjms/3.1.3 | A macro-ecological approach to predators' functional response | Matthieu Barbier, Laurie Wojcik, Michel Loreau | <p>Predation often deviates from the law of mass action: many micro- and meso-scale experiments have shown that consumption saturates with resource abundance, and decreases due to interference between consumers. But does this observation hold at m... | ![]() | Community ecology, Food webs, Meta-analyses, Theoretical ecology | Samir Simon Suweis | 2019-11-08 15:42:16 | View | |
31 Aug 2023
![]() Assessing species interactions using integrated predator-prey modelsMatthieu Paquet, Frederic Barraquand https://doi.org/10.32942/X2RC7WAddressing the daunting challenge of estimating species interactions from count dataRecommended by Tim CoulsonTrophic interactions are at the heart of community ecology. Herbivores consume plants, predators consume herbivores, and pathogens and parasites infect, and sometimes kill, individuals of all species in a food web. Given the ubiquity of trophic interactions, it is no surprise that ecologists and evolutionary biologists strive to accurately characterize them. The outcome of an interaction between individuals of different species depends upon numerous factors such as the age, sex, and even phenotype of the individuals involved and the environment in which they are in. Despite this complexity, biologists often simplify an interaction down to a single number, an interaction coefficient that describes the average outcome of interactions between members of the populations of the species. Models of interacting species tend to be very simple, and interaction coefficients are often estimated from time series of population sizes of interacting species. Although biologists have long known that this approach is often approximate and sometimes unsatisfactory, work on estimating interaction strengths in more complex scenarios, and using ecological data beyond estimates of abundance, is still in its infancy. In their paper, Matthieu Paquet and Frederic Barraquand (2023) develop a demographic model of a predator and its prey. They then simulate demographic datasets that are typical of those collected by ecologists and use integrated population modelling to explore whether they can accurately retrieve the values interaction coefficients included in their model. They show that they can with good precision and accuracy. The work takes an important step in showing that accurate interaction coefficients can be estimated from the types of individual-based data that field biologists routinely collect, and it paves for future work in this area. As if often the case with exciting papers such as this, the work opens up a number of other avenues for future research. What happens as we move from demographic models of two species interacting such as those used by Paquet and Barraquand to more realistic scenarios including multiple species? How robust is the approach to incorrectly specified process or observation models, core components of integrated population modelling that require detailed knowledge of the system under study? Integrated population models have become a powerful and widely used tool in single-species population ecology. It is high time the techniques are extended to community ecology, and this work takes an important step in showing that this should and can be done. I would hope the paper is widely read and cited. References Paquet, M., & Barraquand, F. (2023). Assessing species interactions using integrated predator-prey models. EcoEvoRxiv, ver. 2 peer-reviewed and recommended by Peer Community in Ecology. https://doi.org/10.32942/X2RC7W | Assessing species interactions using integrated predator-prey models | Matthieu Paquet, Frederic Barraquand | <p style="text-align: justify;">Inferring the strength of species interactions from demographic data is a challenging task. The Integrated Population Modelling (IPM) approach, bringing together population counts, capture-recapture, and individual-... | ![]() | Community ecology, Demography, Euring Conference, Food webs, Population ecology, Statistical ecology | Tim Coulson | Ilhan Özgen-Xian | 2023-01-05 17:02:22 | View |
31 May 2023
Conservation networks do not match the ecological requirements of amphibiansMatutini Florence, Jacques Baudry, Marie-Josée Fortin, Guillaume Pain, Joséphine Pithon https://doi.org/10.1101/2022.07.18.500425Amphibians under scrutiny - When human-dominated landscape mosaics are not in full compliance with their ecological requirementsRecommended by Sandrine CharlesAmong vertebrates, amphibians are one of the most diverse groups with more than 7,000 known species. Amphibians occupy various ecosystems, including forests, wetlands, and freshwater habitats. Amphibians are known to be highly sensitive to changes in their environment, particularly to water quality and habitat degradation, so that monitoring abundance of amphibian populations can provide early warning signs of ecosystem disturbances that may also affect other organisms including humans (Bishop et al., 2012). Accordingly, efforts in habitat preservation and sustainable land and water management are necessary to safeguard amphibian populations. In this context, Matutini et al. (2023) compared ecological requirements of amphibian species with the quality of agricultural landscape mosaics. Doing so, they identified critical gaps in existing conservation tools that include protected areas, green infrastructures, and inventoried sites. Matutini et al. (2023) focused on nine amphibian species in the Pays-de-la-Loire region where the landscape has been fashioned over the years by human activities. Three of the chosen amphibian species are living in a dense hedgerow mosaic landscape, while five others are more generalists. Matutini et al. (2023) established multi-species habitat suitability maps, together with their levels of confidence, by combining single species maps with a probabilistic stacking method at 500-m resolution. From these maps, habitats were classified in five categories, from not suitable to highly suitable. Then, the circuit theory was used to map the potential connections between each highly suitable patch at the regional scale. Finally, comparing suitability maps with existing conservation tools, Matutini et al. (2023) were able to assess their coverage and efficiency. Whatever their species status (endangered or not), Matutini et al. (2023) highlighted some discrepancies between the ecological requirements of amphibians in terms of habitat quality and the conservation tools of the landscape mosaic within which they are evolving. More specifically, Matutini et al. (2023) found that protected areas and inventoried sites covered only a small proportion of highly suitable habitats, while green infrastructures covered around 50% of the potential habitat for amphibian species. Such a lack of coverage and efficiency of protected areas brings to light that geographical sites with amphibian conservation challenges are known but not protected. Regarding the landscape fragmentation, Matutini et al. (2023) found that generalist amphibian species have a more homogeneous distribution of suitable habitats at the regional scale. They also identified two bottlenecks between two areas of suitable habitats, a situation that could prove critical to amphibian movements if amphibians were forced to change habitats to global change. In conclusion, Matutini et al. (2023) bring convincing arguments in support of land-use species-conservation planning based on a better consideration of human-dominated landscape mosaics in full compliance with ecological requirements of the species that inhabit the regions concerned. ReferencesBishop, P.J., Angulo, A., Lewis, J.P., Moore, R.D., Rabb, G.B., Moreno, G., 2012. The Amphibian Extinction Crisis - what will it take to put the action into the Amphibian Conservation Action Plan? Sapiens - Surveys and Perspectives Integrating Environment and Society 5, 1–16. http://journals.openedition.org/sapiens/1406 Matutini, F., Baudry, J., Fortin, M.-J., Pain, G., Pithon, J., 2023. Conservation networks do not match ecological requirements of amphibians. bioRxiv, ver. 3 peer-reviewed and recommended by Peer Community in Ecology. https://doi.org/10.1101/2022.07.18.500425 | Conservation networks do not match the ecological requirements of amphibians | Matutini Florence, Jacques Baudry, Marie-Josée Fortin, Guillaume Pain, Joséphine Pithon | <p style="text-align: justify;">1. Amphibians are among the most threatened taxa as they are highly sensitive to habitat degradation and fragmentation. They are considered as model species to evaluate habitats quality in agricultural landscapes. I... | Biodiversity, Biogeography, Human impact, Landscape ecology, Macroecology, Spatial ecology, Metacommunities & Metapopulations, Species distributions, Terrestrial ecology | Sandrine Charles | 2022-09-20 14:40:03 | View | ||
06 Nov 2023
![]() Influence of mimicry on extinction risk in Aculeata: a theoretical approachMaxime Boutin, Manon Costa, Colin Fontaine, Adrien Perrard, Violaine Llaurens https://doi.org/10.1101/2022.10.21.513153Mullerian and Batesian mimicry can influence population and community dynamicsRecommended by Amanda Franklin based on reviews by Jesus Bellver and 1 anonymous reviewerMimicry between species has long attracted the attention of scientists. Over a century ago, Bates first proposed that palatable species should gain a benefit by resembling unpalatable species (Bates 1862). Not long after, Müller suggested that there could also be a mutual advantage for two unpalatable species to mimic one another to reduce predator error (Müller 1879). These forms of mimicry, Batesian and Müllerian, are now widely studied, providing broad insights into behaviour, ecology and evolution. Numerous taxa, including both invertebrates and vertebrates, show examples of Batesian or Müllerian mimicry. Bees and wasps provide a particularly interesting case due to the differences in defence between females and males of the same species. While both males and females may display warning colours, only females can sting and inject venom to cause pain and allow escape from predators. Therefore, males are palatable mimics and can resemble females of their own species or females of another species (dual sex-limited mimicry). This asymmetry in defence could have impacts on both population structure and community assembly, yet research into mimicry largely focuses on systems without sex differences. Here, Boutin and colleagues (2023) use a differential equations model to explore the effect of mimicry on population structure and community assembly for sex-limited defended species. Specifically, they address three questions, 1) how do female noxiousness and sex-ratio influence the extinction risk of a single species?; 2) what is the effect of mimicry on species co-existence? and 3) how does dual sex-limited mimicry influence species co-existence? Their results reveal contexts in which populations with undefended males can persist, the benefit of Müllerian mimicry for species coexistence and that dual sex-limited mimicry can have a destabilising impact on species coexistence. The results not only contribute to our understanding of how mimicry is maintained in natural systems but also demonstrate how changes in relative abundance or population structure of one species could impact another species. Further insight into the population and community dynamics of insects is particularly important given the current population declines (Goulson 2019; Seibold et al 2019). References Bates, H. W. 1862. Contributions to the insect fauna of the Amazon Valley, Lepidoptera: Heliconidae. Trans. Linn. Soc. Lond. 23:495- 566. https://doi.org/10.1111/j.1096-3642.1860.tb00146.x Boutin, M., Costa, M., Fontaine, C., Perrard, A., Llaurens, V. 2022 Influence of sex-limited mimicry on extinction risk in Aculeata: a theoretical approach. bioRxiv, ver. 2 peer-reviewed and recommended by Peer Community in Ecology. https://doi.org/10.1101/2022.10.21.513153 Goulson, D. 2019. The insect apocalypse, and why it matters. Curr. Biol. 29: R967-R971. https://doi.org/10.1016/j.cub.2019.06.069 Müller, F. 1879. Ituna and Thyridia; a remarkable case of mimicry in butterflies. Trans. Roy. Entom. Roc. 1879:20-29. Seibold, S., Gossner, M. M., Simons, N. K., Blüthgen, N., Müller, J., Ambarlı, D., ... & Weisser, W. W. 2019. Arthropod decline in grasslands and forests is associated with landscape-level drivers. Nature, 574: 671-674. https://doi.org/10.1038/s41586-019-1684-3 | Influence of mimicry on extinction risk in Aculeata: a theoretical approach | Maxime Boutin, Manon Costa, Colin Fontaine, Adrien Perrard, Violaine Llaurens | <p style="text-align: justify;">Positive ecological interactions, such as mutualism, can play a role in community structure and species co-existence. A well-documented case of mutualistic interaction is Mullerian mimicry, the convergence of colour... | ![]() | Biodiversity, Coexistence, Eco-evolutionary dynamics, Evolutionary ecology, Facilitation & Mutualism | Amanda Franklin | 2022-10-25 19:11:55 | View | |
26 Aug 2024
![]() Urban Cepaea nemoralis snails are less likely to have nematodes trapped within their shellsMaxime Dahirel, Hannah Reyné, Katrien De Wolf, Dries Bonte https://doi.org/10.1101/2024.03.07.583959Urbanisation linked to a decline in the proportion of snails with trapped nematodes in their shellRecommended by Alison Duncan based on reviews by Robbie Rae and 1 anonymous reviewerUrbanisation modifies species’ habitats affecting their density, distribution, fitness, and behaviour with knock-on effects for their parasites’ abundance and transmission (Bradley & Altizer 2007). A meta-analysis found that changes in resource provisioning due to anthropogenic change can have both positive and negative effects on parasite infection in wildlife populations, but that feeding on urban waste had an effect of reducing infection, especially for helminths and protozoa (Becker, Streicker & Altizer 2015). Another study found that urbanisation reduced ectoparasite load in birds, but had no effect on endoparasites or avian flu (Reid et al. 2024). These changes may be due to novel diets reducing transmission via predation upon trophic hosts (Becker, Streicker & Altizer 2015) or behavioural, leading to more time available to preen (Reid et al. 2024). Less is known about how urbanisation affects invertebrates (but see Lewthwaite et al., 2024) and their parasites. This is important considering that invertebrates are often intermediate hosts of, and/or vector other parasites. Recent work has found that snails and slugs can trap nematodes in their shells to prevent infection (Rae 2017). This newly discovered resistance mechanism reveals that the shell serves an immune defence function. It also provides a record of nematode exposure and documents incidences of resistance to infection as the trapped nematode becomes fixed onto the shell surface (Rae 2017). Dahirel and co-authors exploit this to investigate whether snail-nematode interactions change in response to increasing levels of urbanisation (Dahirel et al. 2024). They explore whether the proportion of Cepaea nemoralis snails with trapped nematodes in their shell changes across an urbanisation gradient. They also explore whether different phenotypic snail traits, notably shell size, colour, band number and fusion explain the likelihood of having trapped nematodes in their shells. An increase in urbanisation was associated with a decrease in the proportion of snails with trapped nematodes in their shells. At the same time larger shells were more likely to have trapped nematodes, but this effect did not change across the urbanisation gradient. The authors discuss that reduced nematode encapsulation in urban environments may be due to lower encounter rate due to either fewer nematodes in urban environments, changes in snail behaviour reducing exposure, or alternatively that urban snails were less resistant to nematode infection. It will be interesting to investigate how this resistance mechanism is related to other forms of snail immunity and whether high rates of nematode encapsulation are an indicator of high resistance or high exposure. This will enable nematode trapping to be used as a marker to indicate environments and/or snail populations harbouring high levels of parasitism and further exploitation of museum collections to understand host-parasite interactions in the past (Rae 2017). References Becker, D.J., Streicker, D.G. & Altizer, S. (2015) Linking anthropogenic resources to wildlife-pathogen dynamics: a review and meta-analysis. Ecol Lett, 18, 483-495. https://doi.org/10.1111/ele.12428 Bradley, C.A. & Altizer, S. (2007) Urbanization and the ecology of wildlife diseases. Trends Ecol Evol, 22, 95-102. https://doi.org/10.1016/j.tree.2006.11.001 Maxime Dahirel, Hannah Reyné, Katrien De Wolf, Dries Bonte (2024) Urban Cepaea nemoralis snails are less likely to have nematodes trapped within their shells. bioRxiv, ver.4 peer-reviewed and recommended by PCI Ecology https://doi.org/10.1101/2024.03.07.583959 Lewthwaite, J.M.M., Baiotto, T.M., Brown, B.V., Cheung, Y.Y., Baker, A.J., Lehnen, C., McGlynn, T.P., Shirey, V., Gonzalez, L., Hartop, E., Kerr, P.H., Wood, E. & Guzman, L.M. (2024) Drivers of arthropod biodiversity in an urban ecosystem. Sci Rep, 14, 390. https://doi.org/10.1038/s41598-023-50675-3 Rae, R. (2017) The gastropod shell has been co-opted to kill parasitic nematodes. Sci Rep, 7, 4745. https://doi.org/10.1038/s41598-017-04695-5 Reid, R., Capilla-Lasheras, P., Haddou, Y., Boonekamp, J. & Dominoni, D.M. (2024) The impact of urbanization on health depends on the health metric, life stage and level of urbanization: a global meta-analysis on avian species. Proc Biol Sci, 291, 20240617. https://doi.org/10.1098/rspb.2024.0617 | Urban *Cepaea nemoralis* snails are less likely to have nematodes trapped within their shells | Maxime Dahirel, Hannah Reyné, Katrien De Wolf, Dries Bonte | <p style="text-align: justify;">Urbanisation is a major human-induced environmental change which can impact not only individual species, but also the way these species interact with each other. As a group, terrestrial molluscs interact frequently ... | ![]() | Host-parasite interactions, Human impact | Alison Duncan | 2024-03-11 11:35:15 | View | |
26 May 2023
Using repeatability of performance within and across contexts to validate measures of behavioral flexibilityMcCune KB, Blaisdell AP, Johnson-Ulrich Z, Lukas D, MacPherson M, Seitz BM, Sevchik A, Logan CJ https://doi.org/10.32942/X2R59KDo reversal learning methods measure behavioral flexibility?Recommended by Aurélie CoulonAssessing the reliability of the methods we use in actually measuring the intended trait should be one of our first priorities when designing a study – especially when the trait in question is not directly observable and is measured through a proxy. This is the case for cognitive traits, which are often quantified through measures of behavioral performance. Behavioral flexibility is of particular interest in the context of great environmental changes that a lot of populations have to experiment. This type of behavioral performance is often measured through reversal learning experiments (Bond 2007). In these experiments, individuals first learn a preference, for example for an object of a certain type of form or color, associated with a reward such as food. The characteristics of the rewarded object then change, and the individuals hence have to learn these new characteristics (to get the reward). The time needed by the individual to make this change in preference has been considered a measure of behavioral flexibility. Although reversal learning experiments have been widely used, their construct validity to assess behavioral flexibility has not been thoroughly tested. This was the aim of McCune and collaborators' (2023) study, through the test of the repeatability of individual performance within and across contexts of reversal learning, in the great-tailed grackle. This manuscript presents a post-study of the preregistered study* (Logan et al. 2019) that was peer-reviewed and received an In Principle Recommendation for PCI Ecology (Coulon 2019; the initial preregistration was split into 3 post-studies).
The first hypothesis was tested by measuring the repeatability of the time needed by individuals to switch color preference in a color reversal learning task (colored tubes), over serial sessions of this task. The second one was tested by measuring the time needed by individuals to switch solutions, within 3 different contexts: (1) colored tubes, (2) plastic and (3) wooden multi-access boxes involving several ways to access food. Despite limited sample sizes, the results of these experiments suggest that there is both temporal and contextual repeatability of behavioral flexibility performance of great-tailed grackles, as measured by reversal learning experiments. Those results are a first indication of the construct validity of reversal learning experiments to assess behavioral flexibility. As highlighted by McCune and collaborators, it is now necessary to assess the discriminant validity of these experiments, i.e. checking that a different performance is obtained with tasks (experiments) that are supposed to measure different cognitive abilities. Coulon, A. (2019) Can context changes improve behavioral flexibility? Towards a better understanding of species adaptability to environmental changes. Peer Community in Ecology, 100019. https://doi.org/10.24072/pci.ecology.100019 Logan, CJ, Lukas D, Bergeron L, Folsom M, & McCune, K. (2019). Is behavioral flexibility related to foraging and social behavior in a rapidly expanding species? In Principle Acceptance by PCI Ecology of the Version on 6 Aug 2019. http://corinalogan.com/Preregistrations/g_flexmanip.html McCune KB, Blaisdell AP, Johnson-Ulrich Z, Lukas D, MacPherson M, Seitz BM, Sevchik A, Logan CJ (2023) Using repeatability of performance within and across contexts to validate measures of behavioral flexibility. EcoEvoRxiv, ver. 5 peer-reviewed and recommended by Peer Community in Ecology. https://doi.org/10.32942/X2R59K | Using repeatability of performance within and across contexts to validate measures of behavioral flexibility | McCune KB, Blaisdell AP, Johnson-Ulrich Z, Lukas D, MacPherson M, Seitz BM, Sevchik A, Logan CJ | <p style="text-align: justify;">Research into animal cognitive abilities is increasing quickly and often uses methods where behavioral performance on a task is assumed to represent variation in the underlying cognitive trait. However, because thes... | Behaviour & Ethology, Evolutionary ecology, Preregistrations, Zoology | Aurélie Coulon | 2022-08-15 20:56:42 | View |
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