Plasmid dynamics in bacterial communities

Salazar de Dios, Afra Nadyesda (2021) Plasmid dynamics in bacterial communities. Master's Research Project 1, Ecology and Evolution.

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Abstract

Plasmids are considered a major driving force of bacterial ecology and evolution. Unlike bacterial chromosomes, plasmids frequently move horizontally from one cell to another. Although plasmid horizontal transmission is usually intraspecific, it can often occur between phylogenetically distant organisms. The collection of distinct organisms that a single plasmid can infect is called the host range. Despite many of the mechanistic barriers limiting host ranges are well known, it is not clear how plasmid host ranges evolve. Evolutionary studies on plasmid host ranges have shown these ranges are very dynamic. Here, I ask what is the expected change in plasmid host range assuming the plasmid’s main objective is to increase its fitness. To answer this question, first it is necessary to identify the components of plasmid fitness on which natural selection can act upon. To derive such components, I develop an eco-evolutionary model of plasmid population dynamics. Specifically, I perform an evolutionary invasion analysis of a trait encoded on a plasmid that affects host growth, competition, conjugation, and plasmid loss. From this analysis, I obtain a fitness function to predict the invasion prospects of a plasmid mutant in an existing plasmid population. My results indicate that there are multiple ways in which plasmids can increase their fitness. I further my analysis by considering trade-offs between different life history traits of the plasmid and discuss possible implications of the plasmid fitness components on host range dynamics. In other words, I discuss how plasmid host ranges would be expected to evolve given the maximization of the plasmid fitness components under scrutiny.

Item Type:	Thesis (Master's Research Project 1)
Supervisor name:	Doorn, G.S. van and Vos, M.G.J. de
Degree programme:	Ecology and Evolution
Thesis type:	Master's Research Project 1
Language:	English
Date Deposited:	30 Jun 2021 09:09
Last Modified:	27 Jul 2021 07:23
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/24521

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