A population genetics analysis of Dictyostelium discoideum's greenbeard genes: assessing genetic diversity, population structure and balancing selection

• Grant number: 23/08473-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2023
• End date: December 31, 2024
• Field of knowledge: Biological Sciences - Genetics
• Principal Investigator: Diogo Meyer
• Grantee: Alfredo Antonio Reis Marin
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 23/18038-6 - Unraveling the polychromatic greenbeard effect: Dictyostelium discoideum's tgr genes through the eyes of balancing selection, BE.EP.IC

Abstract

Dictyostelium discoideum is a social amoeba that displays a unique behavior during periods of food scarcity. Under starvation, the unicellular individuals produce membrane proteins that promote cell adhesion and the resulting multicellular aggregate moves towards a better living environment. There, some of the cells will differentiate into a stalk that supports a spore head, formed by the other individuals. Only the spore-fated cells will actually reproduce, while the stalk-fated ones will act altruistically to improve the other group's success. Two key proteins involved in this process are TgrB1 and TgrC1. They exhibit high degrees of polymorphism in Dictyostelium discoideum populations and act as a kin recognition system, as individuals adhere preferentially to others with the same protein variant resulting in a more efficient aggregate. This entire mechanism closely resembles the greenbeard effect, in which individuals cooperate with others with the same genotype to increase their fitness in relation to non-cooperators. In this project, we aim to analyze the genetic diversity of tgrB1 and tgrC1 genes, their evolutionary rates, and the degree of genetic structure between populations. We will use the findings from these analyses to answer whether balancing selection plays a role in maintaining the high levels of polymorphism observed in these genes. By gaining insights into the mechanisms underlying cooperative behavior at the genetic level, this project aims to contribute to our understanding of the greenbeard effect and its role in social evolution.