The Enigma of Frequency-Dependent Selection [Revised and updated 16 June 1998]

Frequency-dependent selection is so fundamental to modern evolutionary thinking that everyone interested in evolutionary biology 'knows' the concept. It is even so fundamental that many authors of textbooks do not bother to define it. Yet it turns out that different authors (and sometimes even one and the same author) use the term to refer to different types of selection. In this paper we try to uncover the sources of this confusion. The concept is fairly well defined in the original concept of population genetical theory, which focuses on short-term evolutionary change, and basically ignores density-dependence. The problems start when the original concept is used in the context of long-term evolution, in which density-dependence is essential: without density dependence, lines of descent either die out or explode on the relevant time scales. With density-dependence, the definition of frequency-dependent selection, in the form in which it is usually given, becomes ambiguous. The concept of weak and strong frequency-dependence distinguish between two very different forms of frequency-dependent selection occurring in populations which experience density-dependent population regulation

Evolution of Mixed Maturation Strategies in Semelparous Life-histories: the Crucial Role of Dimensionality of Feedback Environment [Updated 18 August 1998]

We study the evolution of age-at-maturity in a semelparous life history with two age-classes. An individual may breed in the first year of its life and die, or delay breeding to the second year. In this setting a mixed strategy means that a fraction of the individual's offspring breed in the first possible breeding event, while the remaining fraction delay breeding. Current theory seems to imply that mixed strategies are not evolutionarily stable strategies (ESS) under a steady state population dynamical regime. We show that a two-dimensional feedback environment may allow the evolution of mixed age-at-maturity. Furthermore, different phenotypes need to perceive the environment differently. The biological reasoning behind these conditions is different resource usage or predation pressure between two age-classes. Thus, the conventional explanations for the occurrence of mixed strategies in natural populations, environmental stochasticity or complex dynamics, are not needed

The heterotrophic glucose uptake potential of three marine dinoflagellates

Kolmen merellisen dinoflagellaatin glukoosinottopotentiaal

Does Density-Dependent Individual Growth Simplify Dynamics in Age-Structured Populations? A General Model Applied to Perch, "Perca fluviatilis"

Availability of resources is a limiting factor for many populations. Diminished resource availability due to intraspecific competition is expected to decrease the annual growth increments of individuals. We study an age- structured population model for individuals with indeterminate growth and annual reproduction; parameters of the model are chosen to characterize a population with life history similar to the Eurasian perch. Different variants of this model are analyzed, all of which have a potential for exhibiting non-equilibrium population fluctuations. We demonstrate that by incorporating density-dependent individual growth into these models changes the dynamics of these populations by damping or even eradicating fluctuations in abundance and biomass. This finding offers an explanation for the observed stable dynamics of unperturbed perch populations. Further, density-dependent individual growth may also be a significant factor for contributing to the conspicuous empirical rarity of non-equilibrium population dynamics in general

Applying Interconnected Game Theory to Analyze Transboundary Waters: A Case Study of the Kura-Araks Basin

A number of environmental problems are international in nature, including many water management issues. Rivers, for example, do not recognize political boundaries. Therefore, pollution generated in one country can affect neighboring countries, while water extraction in an upstream country can affect water flow and water availability in a downstream country. The situation creates an interdependency among countries, which might lead to disputes over the management of transboundary water. Therefore, coordination among the countries is necessary for effective management of these transboundary resources. The focus of a recently published study (Khachaturyan and Schoengold, 2018) is the transboundary Kura-Araks Basin (see Figure 1 for its location), which is a major river system in the South Caucasus, with about 11 million people living in the basin. The countries in the basin are Armenia, Azerbaijan, Georgia, Iran, and Turkey, with Armenia, Azerbaijan, and Georgia having over 80 percent of the streamflow. The Kura-Araks Basin is a primary source of water for agricultural, industrial, and municipal uses in the South Caucasian countries. The study determines whether there are economic benefits to be gained from cooperation in the management of the Kura River (shared between Azerbaijan and Georgia), and under what conditions cooperation is an achievable outcome. Azerbaijan withdraws about 35 percent of the total available renewable water resources while Georgia only withdraws about 3 percent

International Management Strategies for a Migratory Fish Stock: A Bio-economic Simulation Model of the Norwegian Spring-spawning Herring Fishery

In this paper, a three-country dynamic bio-economic model is presented and used to simulate catch levels, stock size and profit potential of alternative management strategies for the Norwegian spring-spawning herring fishery. Management of the herring fishery is complicated by the migratory behaviour of the species moving between coastal state zones and the high seas. The biological model is described by a discrete time age structured model and the economic model is described by a rent maximising model with constant price of herring and different costs of harvesting and efficiency levels for the different national fleets. The simulations are carried out over a 70-year period and show that the benefits of international cooperation far exceed the returns of a competitive open access fishery

Negative density-distribution relationship in butterflies

Peer reviewe

Evolution of predator dispersal in relation to spatio-temporal prey dynamics : how not to get stuck in the wrong place!

Peer reviewedPublisher PD

Advantage of rare infanticide strategies in an invasion experiment of behavioural polymorphism

Killing conspecific infants (infanticide) is among the most puzzling phenomena in nature. Stable polymorphism in such behaviour could be maintained by negative frequency-dependent selection (benefit of rare types). However, it is currently unknown whether there is genetic polymorphism in infanticidal behaviour or whether infanticide may have any fitness advantages when rare. Here we show genetic polymorphism in non-parental infanticide. Our novel invasion experiment confirms negative frequency-dependent selection in wild bank vole populations, where resource benefits allow an infanticidal strategy to invade a population of non-infanticidal individuals. The results show that infanticidal behaviour is highly heritable with genetic correlation across the sexes. Thus, a positive correlative response in male behaviour is expected when selection operates on females only and vice versa. Our results, on one hand, demonstrate potential benefits of infanticide, and on the other, they open a new perspective of correlative evolution of infanticide in females and males

Modeling complex ecological economic systems: toward an evolutionary, dynamic understanding of people and nature

Recent understanding about system dynamics and predictability that has emerged from the study of complex systems is creating new tools for modeling interactions between anthropogenic and natural systems. A range of techniques has become available through advances in computer speed and accessibility and by implementing a broad, interdisciplinary systems view