Unraveling the polychromatic greenbeard effect: Dictyostelium discoideum's tgr genes through the eyes of balancing selection

• Grant number: 23/18038-6
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Start date: April 18, 2024
• End date: August 17, 2024
• Field of knowledge: Biological Sciences - Genetics
• Principal Investigator: Diogo Meyer
• Grantee: Alfredo Antonio Reis Marin
• Supervisor: Jason B Wolf
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: University of Bath, England
• Associated to the scholarship: 23/08473-7 - A population genetics analysis of Dictyostelium discoideum's greenbeard genes: assessing genetic diversity, population structure and balancing selection, BP.IC

Abstract

Throughout this undergraduate research project, our focus is to investigate genetic diversity in Dictyostelium discoideum's "greenbeard genes," namely tgrB1 and tgrC1. This highly polymorphic gene pair is activated at the beginning of the social phase in the amoeba's life cycle, playing a crucial role in an allorecognition system during aggregation. The dynamics of this system can be conceptualized as a polychromatic greenbeard effect, wherein multiple beard colors coexist, and individuals cooperate exclusively with others of the same color. With the objective of formalizing the model for this polychromatic greenbeard effect, we propose this internship project to integrate balancing selection into the study of the greenbeard effect so as to elucidate the maintenance of a high number of colors in such a system. Our approach begins with an exploration of well-established mechanisms in population genetics, synthesizing their analytical descriptions and key results. Subsequently, we will develop agent-based simulations of greenbeard interactions, incorporating each previously synthesized balancing selection regime to understand their impact on beard color diversity. These simulations will be compared to prior results on tgr gene diversity, assessing their ability to accurately replicate observed patterns. A successful model should proficiently reproduce the diversity of beard colors, their distribution among populations, and the evolution of diversity over time. This last aspect will be further examined in the later stages of the project as we explore the molecular evolution of the tgr genes. Additionally, we will leverage our collaboration with the team that originally sequenced the genomes we have employed, addressing alignment issues identified in certain strains during the course of the project.