Coevolutionary Dynamics: From Finite to Infinite Populations

Traditionally, frequency dependent evolutionary dynamics is described by deterministic replicator dynamics assuming implicitly infinite population sizes. Only recently have stochastic processes been introduced to study evolutionary dynamics in finite populations. However, the relationship between deterministic and stochastic approaches remained unclear. Here we solve this problem by explicitly considering large populations. In particular, we identify different microscopic stochastic processes that lead to the standard or the adjusted replicator dynamics. Moreover, differences on the individual level can lead to qualitatively different dynamics in asymmetric conflicts and, depending on the population size, can even invert the direction of the evolutionary process.Comment: 4 pages (2 figs included). Published in Phys. Rev. Lett., December 200

Stochastic slowdown in evolutionary processes

We examine birth--death processes with state dependent transition probabilities and at least one absorbing boundary. In evolution, this describes selection acting on two different types in a finite population where reproductive events occur successively. If the two types have equal fitness the system performs a random walk. If one type has a fitness advantage it is favored by selection, which introduces a bias (asymmetry) in the transition probabilities. How long does it take until advantageous mutants have invaded and taken over? Surprisingly, we find that the average time of such a process can increase, even if the mutant type always has a fitness advantage. We discuss this finding for the Moran process and develop a simplified model which allows a more intuitive understanding. We show that this effect can occur for weak but non--vanishing bias (selection) in the state dependent transition rates and infer the scaling with system size. We also address the Wright-Fisher model commonly used in population genetics, which shows that this stochastic slowdown is not restricted to birth-death processes.Comment: 8 pages, 3 figures, accepted for publicatio

Evolutionary processes from the perspective of flowering time diversity.

Although it is well appreciated that genetic studies of flowering time regulation have led to fundamental advances in the fields of molecular and developmental biology, the ways in which genetic studies of flowering time diversity have enriched the field of evolutionary biology have received less attention despite often being equally profound. Because flowering time is a complex, environmentally responsive trait that has critical impacts on plant fitness, crop yield, and reproductive isolation, research into the genetic architecture and molecular basis of its evolution continues to yield novel insights into our understanding of domestication, adaptation, and speciation. For instance, recent studies of flowering time variation have reconstructed how, when, and where polygenic evolution of phenotypic plasticity proceeded from standing variation and de novo mutations; shown how antagonistic pleiotropy and temporally varying selection maintain polymorphisms in natural populations; and provided important case studies of how assortative mating can evolve and facilitate speciation with gene flow. In addition, functional studies have built detailed regulatory networks for this trait in diverse taxa, leading to new knowledge about how and why developmental pathways are rewired and elaborated through evolutionary time

The conceptual structure of evolutionary biology: A framework from phenotypic plasticity

In this review, I approach the role of phenotypic plasticity as a key aspect of the conceptual framework of evolutionary biology. The concept of phenotypic plasticity is related to other relevant concepts of contemporary research in evolutionary biology, such as assimilation, genetic accommodation and canalization, evolutionary robustness, evolvability, evolutionary capacitance and niche construction. Although not always adaptive, phenotypic plasticity can promote the integration of these concepts to represent some of the dynamics of evolution, which can be visualized through the use of a conceptual map. Although the use of conceptual maps is common in areas of knowledge such as psychology and education, their application in evolutionary biology can lead to a better understanding of the processes and conceptual interactions of the complex dynamics of evolution. The conceptual map I present here includes environmental variability and variation, phenotypic plasticity and natural selection as key concepts in evolutionary biology. The evolution of phenotypic plasticity is important to ecology at all levels of organization, from morphological, physiological and behavioral adaptations that influence the distribution and abundance of populations to the structuring of assemblages and communities and the flow of energy through trophic levels. Consequently, phenotypic plasticity is important for maintaining ecological processes and interactions that influence the complexity of biological diversity. In addition, because it is a typical occurrence and manifests itself through environmental variation in conditions and resources, plasticity must be taken into account in the development of management and conservation strategies at local and global levels