Evolutionary and Molecular Determinants of a Nutritional Polyphenism

Introduction

Environmental fluctuations are a general challenge for organisms, exacerbated in the context of global change. Many animals evolve phenotypically plastic responses to adjust to new conditions. Polyphenism is an original mechanism that produces specialized morphs to track environmental changes.

Research Question

Whether the molecular mechanisms underlying polyphenism evolve from the acquisition of novel genes or the rewiring of conserved environment-sensing pathways is an unresolved and challenging question. This requires well-characterized regulatory networks, including the involvement of host-microbiota molecular interactions, and relevant phylogenetic frameworks to root the evolutionary steps through which polyphenism emerged.

Project Objectives

ALTEREVO aims to understand how a nutrient-sensitive polyphenism evolves and is regulated. The specific objectives include:

1. Characterizing the molecular regulation of nutritional polyphenism using aphids and their symbionts.
2. Inducing alternative morphs adapted to distinct host plants.
3. Elucidating how this polyphenism machinery became genetically encoded.
4. Addressing for the first time the role of symbionts on the evolution and regulation of animal polyphenisms.

Methodology

To fulfill these objectives, ALTEREVO proposes an original approach linking the evolutionary, molecular, and ecological components of polyphenism, incorporating the involvement of symbionts. The methodology includes:

• Metabolomics: Identifying plant compounds inducing alternative phenotypes.
• Large-scale gene expression and epigenetic analyses: Revealing the molecular cascade regulating morph determination.
• Functional characterization of candidate genes.
• Phylogenomics: Elucidating nutritional polyphenism evolution.

Expected Outcomes

This project will lead to major progress on the mechanisms allowing rapid phenotypic adjustments to environmental fluctuations and on the role of phenotypic plasticity in evolution in a holobiont context. These advances are of fundamental importance for assessing the resilience of populations to human-induced changes.