Mots-Clés

évolution des familles multigéniques phylogénie évolution moléculaire récepteurs olfactifs insectes hyménoptères

Description

INTRODUCTION, SCIENTIFIC CONTEXT:

Sensory systems are at the interface between an animal’s environment and its physiology and behavior. They determine how animals perceive the world, and respond to it through their behavior. Consequently, our working hypothesis is that the evolution of sensory systems plays a central role in the adaptation of behavior to environmental change or the occupation of new ecological niches. By combining new methods in genomics, genetics and neuroethology, we want to explore different facets of the evolution of sensory systems, in particular chemosensory systems, and their involvement in a major transition in the organization of living organisms, i.e. the appearance of the highest degree of social life (eusociality). Our study models are mainly hymenopteran insects, an order known to have undergone at least 9 independent emergences of eusociality (Couto, et al. 2023). We want to work on both social Hymenoptera (honey bees, bumblebees, vespid wasps and ants) and solitary ones (parasitic wasps, solitary bees, etc.) to examine this question, but also other aspects of their evolution such as new prey detection in parasitic wasps.

Hymenopterans are outstanding both in terms of the number of species, more than 150,000 species described, and the diversity at the morphological, physiological, ecological and behavioral levels (Peters, et al. 2017). We know that chemoreception plays an essential role in these insects. Three large gene families are involved in chemoreception, the GRs, the ORs and the IRs. The latter having an origin which is independent to the GR and OR (Wicher and Miazzi 2021). We planned to study the evolutionary dynamics of these gene families in relation with the evolution of biological and ecological characteristics in different Hymenoptera lineages, in particular with respect to eusociality and parasitism. The evolution of these gene families has already been studied in Hymenoptera, but at a small scale, including only a few species and often only a subset of receptor-encoding genes (Zhou, et al. 2015).

RESEARCH PROPOSAL/OBJECTIVES:

Completely automated and reliable pipelines have not been developed to identify all insect chemoreceptors. We wish to develop a bioinformatics tool allowing us to obtain complete repertoires of chemoreceptors for a large number of species, in order to be able to reconstruct finer scenarios on the coevolution of receptor families with biological and environmental factors.

DESCRIPTION OF DATA if applicable (Data must be available before the start of the internship):

The number of Hymenoptera genomes is growing very fast (> 700 genomes currently available) and for a large diversity of species belonging to many families allowing to explore several evolutionary issues.

Moreover, there are several databases containing information about the biology of hymenopterans.

METHODOLOGIES:

To carry out this research program, we will adapt a pipeline developed to study of vertebrate olfactory and taste receptors (Policarpo, et al. 2024). The gene families in vertebrates are not orthologous of those present in insects, that is to say they correspond to independent exaptations. First, we will have to produce databases with known hymenopteran genes coding for OR, GR and IR receptors identified in the genomes of a few model species and fine tune some parameters of the pipeline to automatically identify these genes in other hymenopteran genomes. Once the pipeline will be validated by comparing the gene repertoire identified with the one known for some well-studied species, we will apply our tool to all available genomes. Then, we will use various tools, most based on analyses of phylogenetic trees to examine several evolutionary questions. We will analyze the dynamics of the number of genes in different gene families/subfamilies, looking for extreme expansions or contractions that could be evidence of drastic environmental changes (Policarpo, et al. 2024). Phylogenetic comparative analyses will be performed to find correlation between the dynamics of gene families/subfamilies and anatomical and physiological characters, and environmental factors (Policarpo, et al. 2024).

FIVE REFERENCES:

Couto A, Marty S, Dawson EH, d'Ettorre P, Sandoz J-C, Montgomery SH. 2023. Evolution of the neuronal substrate for kin recognition in social Hymenoptera. Biological Reviews 98:2226-2242.

Peters RS, Krogmann L, Mayer C, Donath A, Gunkel S, Meusemann K, Kozlov A, Podsiadlowski L, Petersen M, Lanfear R, et al. 2017. Evolutionary History of the Hymenoptera. Current Biology 27:1013-1018.

Policarpo M, Baldwin MW, Casane D, Salzburger W. 2024. Diversity and evolution of the vertebrate chemoreceptor gene repertoire. Nature Communications 15:1421.

Wicher D, Miazzi F. 2021. Functional properties of insect olfactory receptors: ionotropic receptors and odorant receptors. Cell Tissue Res 383:7-19.

Zhou X, Rokas A, Berger SL, Liebig J, Ray A, Zwiebel LJ. 2015. Chemoreceptor Evolution in Hymenoptera and Its Implications for the Evolution of Eusociality. Genome Biol Evol 7:2407-2416.