Biology subjects

Morsky, B.

Publications and source records attributed to Morsky, B..

5 recordsLinked to original sources

bioRxiv2022

The evolution of partner specificity in mutualisms

Mutualistic species vary in their level of partner specificity, which has important evolutionary, ecological, and management implications. Yet, the evolutionary mechanisms which underpin partner specificity are not fully understood. Most work on specialization focuses on the trade-off between generalism and specialism, where specialists receive more benefits from preferred partners at the expense of benefits from non-preferred partners, while generalists receive similar benefits from all partners. Because all mutualisms involve some degree of both cooperation and conflict between partners, we highlight that specialization to a mutualistic partner can be cooperative, increasing benefit to a focal species and a partner, or antagonistic, increasing resource extraction by a focal species from a partner. We devise an evolutionary game theoretic model to assess the evolutionary dynamics of cooperative specialization, antagonistic specialization, and generalism. Our model shows that cooperative specialization leads to bistability: stable equilibria with a specialist host and its preferred partner excluding all others. We also show that under cooperative specialization with spatial effects, generalists can thrive at the boundaries between differing specialist patches. Under antagonistic specialization, generalism is evolutionarily stable. We provide predictions for how a cooperation-antagonism continuum may determine the patterns of partner specificity that develop within mutualistic relationships.

evolutionary biology↗

bioRxiv2021

Suppressing evolution through environmental switching

Ecology and evolution under changing environments are important in many subfields of biology with implications for medicine. Here, we explore an example: the consequences of fluctuating environments on the emergence of antibiotic resistance, which is an immense and growing problem. Typically, high doses of antibiotics are employed to eliminate the infection quickly and minimize the time under which resistance may emerge. However, this strategy may not be optimal. Since competition can reduce fitness and resistance typically has a reproductive cost, resistant mutants fitness can depend on their environment. Here we show conditions under which environmental varying fitness can be exploited to prevent the emergence of resistance. We develop a stochastic Lotka-Volterra model of a microbial system with competing phenotypes: a wild strain susceptible to the antibiotic, and a mutant strain that is resistant. We investigate the impact of various pulsed applications of antibiotics on population suppression. Leveraging competition, we show how a strategy of environmental switching can suppress the infection while avoiding resistant mutants. We discuss limitations of the procedure depending on the microbe and pharmacodynamics and methods to ameliorate them.

ecology↗

bioRxiv2020

Evolution of contribution timing in public goods games

Life history strategies are a crucial aspect of life, which are complicated in group-living species, where payoffs additionally depend on others behaviours. Previous theoretical models of public good games have generally focused on the amounts individuals contribute to the public good. Yet a much less studied strategic aspect of public good games, the timing of contributions, can also have dramatic consequences for individual and collective performance. Here, we develop game theoretical models to explore how the timing of contributions evolves. We show how contributing rapidly is not necessarily optimal, since delayers can act as "cheats," avoiding contributing while reaping the benefits of the public good. However, delaying too long can put the delayers at a disadvantage as they can miss out on the benefits. These effects lead to bistability in a single group, and spatial diversity among multiple interacting groups.

evolutionary biology↗

bioRxiv2018

The blind choreographer: evolution of social norms and correlated equilibria

Social norms regulate and coordinate most aspects of human social life, yet they emerge and change as a result of individual behaviours, beliefs, and expectations. A satisfactory account for the evolutionary dynamics of social norms therefore has to link individual beliefs and expectations to population-level dynamics, where individual norms change according to their consequences for individuals. Here we present a new model of evolutionary dynamics of social norms that encompasses this objective and addresses the emergence of social norms. In this model, a norm is a set of behavioural prescriptions and a set of environmental descriptions that describe the expected behaviours of those with whom the norm holder will interact. These pre-scriptions and descriptions are functions of exogenous environmental events. These events have no intrinsic meaning or effect on the payoffs to individuals, yet beliefs/- superstitions regarding them can effectuate coordination. Though a norm's prescriptions and descriptions are dependent upon one another, we show how they emerge from random accumulations of beliefs. We categorize the space of social norms into several natural classes and study the evolutionary competition between these classes of norms. We apply our model to the Game of Chicken and the Nash Bargaining Game. Further, we show how the space of norms and evolutionary stability is dependent upon the correlation structure of the environment, and under which such correlation structures social dilemmas can be ameliorated or exacerbated.

evolutionary biology↗

bioRxiv2017

Cheater-altruist synergy in immunopathogenic ecological public goods games

Much research has focused on the deleterious effects of free-riding in public goods games, and a variety of mechanisms that suppresses cheating behavior. Here we argue that under certain conditions cheating behavior can be beneficial to the population. In a public goods game, cheaters do not pay for the cost of the public goods, yet they receive the benefit. Although this free-riding harms the entire population in the long run, the success of cheaters may aid the population when there is a common enemy that antagonizes both cooperators and cheaters. Here we study models in which an immune system antagonizes a cooperating pathogen. We investigate three population dynamics models, and determine under what conditions the presence of cheaters help defeat the immune system. The mechanism of action is that a polymorphism of cheaters and altruists optimizes the average growth rate. Our results give support for a possible synergy between cooperators and cheaters in ecological public goods games.

ecology↗