Biology subjects

Audusseau, H.

Publications and source records attributed to Audusseau, H..

5 recordsLinked to original sources

bioRxiv2024

Modelling the spatiotemporal dynamics of multispecies population interactions in the context of climate change

O_LISpecies interactions are fundamental to the stability and productivity of ecosystems. To improve our capacity to predict and understand how climate change shapes the distribution of species and the dynamics of biotic interactions, we need to develop spatially explicit multi-species models that are built upon species-specific responses to changing conditions. C_LIO_LIWe developed a two-dimensional diffusion-advection-reaction predator-prey model that integrates species-specific responses to heterogeneous landscapes, affecting species dispersal, reproduction and survival rates. We derived conditions for the stability and feasibility of the coexistence steady-state and observed how temperature variation stabilises or destabilises the system. C_LIO_LIWe conducted numerical simulations to explore the effect of predicted extreme temperatures on the spatial dynamics of a parasitoid-butterfly system and their interactions. Applied to four different climatic environments, the numerical approximations demonstrate the asymmetric impact of a warming climate on interacting species. The output density distribution maps highlight the capability of our model to produce interpretable multiscale predictions which can be used to identify and evaluate species vulnerability locally and across their range. C_LIO_LIBy building upon a solid mechanistic understanding of species-specific responses to environmental change, our model can be extended to other species and variables, including environments where the availability of empirical data is limited, and explore the dynamics and distribution of interacting species under different scenarios of environmental change. C_LI

ecology↗

bioRxiv2023

Shifts in colour morph frequencies along an urbanisation gradient in the ground beetle Pterostichus madidus

Cities impose strong ecological constraints on many species. It is often difficult to know whether phenotypic responses to urbanisation are due to (adaptive) evolutionary responses, as opposed to e.g. plastic responses. A solution is to focus on traits for which variation is only or mostly genetic in origin, since changes are then likely to reflect evolutionary processes. For this purpose, we studied the leg-colour polymorphism of a common carabid beetle, Pterostichus madidus, along an urbanisation gradient. We observed that black-legged individuals were more frequent than red-legged individuals in urban areas. Whether these changes result from natural selection or non-selective evolutionary forces is uncertain. However, if this phenotypic change is adaptive in nature, higher urban temperatures are likely to be the driver. Specifically, our results are consistent with previous data showing that black-legged individuals have a behavioural advantage in warmer (micro)climates, and contradict the thermal melanism hypothesis that predicts they would experience stronger negative effects of higher temperatures in cities.

evolutionary biology↗

bioRxiv2022

Reproductive strategies in a complex of simultaneously hermaphroditic species, the Allolobophora chlorotica case study

An in-depth knowledge of reproductive strategies is essential to understand the evolutionary history of species and their resulting patterns of taxonomic diversity. In particular, the study of life history traits related to reproduction could help to resolve the speciation patterns in the cryptic species complexes recently found in earthworms. Here, we carried out a parentage analysis in such a complex, the Allolobophora chlorotica aggregate. Using four nuclear microsatellite markers and a fragment of the cytochrome c oxidase subunit I mitochondrial gene we investigated (i) the mating strategies between individuals belonging to two divergent mitochondrial lineages (L2 and L3) that cannot be distinguished with nuclear markers and (ii) the reproductive isolation between lineages that are differentiated both at the mitochondrial and nuclear level (L2/L3 and L1). Among the 157 field collected individuals, 66 adults were used in cross-breeding experiments to form 22 trios based on their assignment to a mitochondrial lineage, and 453 obtained juveniles were genotyped. We showed that adults that mated with both their potential mates in the trio produced significantly more juveniles. In L2 and L3 crosses, a sex-specific pattern of reproduction characteristic to each lineage was observed, suggesting a possible conflict of interest between mating partners. In L2/L3 and L1 crosses, a high production of cocoons was counterbalanced by a low hatching rate, suggesting a post-zygotic reproductive isolation. Reproductive strategies are thus likely to contributed to the diversification of this complex of species and we advocate further studies on sexual selection and sex allocation in earthworms.

evolutionary biology↗

bioRxiv2020

Ecology and population genetics of the parasitoid Phobocampe confusa (Hymenoptera: Ichneumonidae) in relation to its hosts, Aglais species (Lepidoptera: Numphalidae).

The biology of parasitoids in natural ecosystems remain very poorly studied, while they are key species for their functioning. Here we focused on Phobocampe confusa, a vanessines specialist, responsible for high mortality rates in very emblematic butterfly species in Europe (genus Aglais). We studied its ecology and genetic structure in connection with those of its host butterflies in Sweden. To this aim, we gathered data from 428 P. confusa individuals reared from 6094 butterfly larvae (of A. urticae, A. io and in two occasions of Araschnia levana) collected over two years (2017 and 2018) and 19 sites distributed along a 500 km latitudinal gradient. We found that P. confusa is widely distributed along the latitudinal gradient. Its distribution is constrained over time by the phenology of its hosts. The large variation in climatic conditions between sampling years explains the decrease in phenological overlap between P. confusa and its hosts in 2018 and the 33.5% decrease in the number of butterfly larvae infected. At least in this study, P. confusa seems to favour A. urticae as host: while it parasitized nests of A. urticae and A. io equally, the proportion of larvae is significantly higher for A. urticae. At the landscape scale, P. confusa is almost exclusively found in vegetated open land and near deciduous forests, whereas artificial habitats are negatively correlated with the likelihood of a nest to be parasitized. The genetic analyses on 89 adult P. confusa and 87 adult A. urticae using COI and AFLP markers reveal a low genetic diversity in P. confusa and a lack of population genetic structure in both species, at the scale of our sampling. Further genetic studies using high-resolution genomics tools will be required to better understand the population genetic structure of P. confusa, its biotic interactions with its hosts, and ultimately the stability and the functioning of natural ecosystems.Competing Interest StatementThe authors have declared no competing interest.View Full Text

zoology↗

bioRxiv2020

Altered parasitism of a butterfly assemblage associated with a range-expanding species

AimBiotic interactions are an important factor structuring ecological communities but data scarcity limits our understanding of the impact of their response to climate and land use changes on communities. We studied the impact of a change in species assemblage on biotic interactions in a community of closely-related butterflies. Specifically, we examined the impact of the recent range expansion of Araschnia levana on the resident species, with a particular focus on natural enemies, parasitoids, shared with other butterfly species in the assemblage. LocationSweden. Time periodTwo years (2017-2018). Major taxa studiedNettle-feeding butterflies (Aglais urticae, Aglais io, Araschnia levana, and Vanessa atalanta) and their parasitoids. MethodsWe assessed parasitism in 6777 butterfly larvae sampled in the field from 19 sites distributed along a 500 km latitudinal gradient, and every two weeks throughout species reproductive seasons. We identified the parasitoid complex of each butterfly species and their overlap, and analysed how parasitism rates were affected by species assemblage, variations in abundance, time, and the arrival of A. levana. ResultsParasitoids caused high mortality, with substantial overlap across the four host species. The composition of the host community influenced parasitism rates and this effect was specific to each species. In particular, the rate of parasitism in resident species was comparatively higher at sites where A. levana has been established for longer. Main conclusionsParasitoid pressure is a significant source of mortality in the nettle-feeding butterfly community studied. Variations in butterfly species assemblages are associated with substantial variations in rates of parasitism. This is likely to affect the population dynamics of their butterfly host species, and, potentially, the larger number of species with which they interact.

ecology↗