应数学与统计学院的邀请，芬兰赫尔辛基大学（University of Helsinki）数学与统计系教授Stefan A.H. Geritz于6月28日-7月9日来我校进行学术交流并作系列学术报告。
主题是：The theory of adaptive dynamics and its application in ecology and infectious diseases.
报告（一）
题 目：Introduction to adaptive dynamics: basic concepts and techniques
时 间：2014年6月30日（周一）， 上午9：00～11：00
地 点：理科楼202
摘 要：Adaptive dynamics (AD) is a mathematical theory of evolution by mutation and selection. It has roots in both game theory and population dynamics, and can be characterized by the following three questions: Firstly, which new strategies can invade a population of already existing strategies, if this new strategy is introduced at an initially very low population density? Secondly, what will be the outcome of such an invasion event in terms of which strategies (i.e., the old ones and the new one) will remain and which will oust when the population reaches a new demographic attractor? Thirdly, what are the long-term consequences of many consecutive invasion events in terms of how the strategy composition of the population changes. In this lecture we introduce basic concepts and techniques of adaptive dynamics together with their application to various examples including predator-prey coevolution.
报告（二）
题 目：Adaptive dynamics and the role of trade-offs between different traits
时 间：2014年7月2日（周三）， 上午9：00～11：00
地 点：理科楼202
摘 要：Positive as well as negative trade-offs between different traits play an important role in the evolution of almost every strategy, e.g., trade-offs between the number and the quality of the offspring of an individual, between the virulence and the infectivity of a disease, between the effectivity of a learned skill and the time spent exercising that skill, and so forth. Small quantitative differences in a given trade-off may have bid qualitative effects on the evolutionary outcome. This is unfortunate, because in the real world, trade-offs are often difficult to quantify at a level that is accurate enough to make qualitative predictions about evolutionary outcomes. In this lecture, we turn the question around and ask what properties must a given trade-off have to produce a given range of qualitatively different kind of evolutionary behaviour. This is illustrated using different examples including the evolution of virulence of a disease.
报告（三）
题 目：The DeAngelis-Beddington functional response and the evolution of timidity of the prey
时 间：2014年7月4日（周五）， 上午9：00～11：00
地 点：理科楼202
摘 要：We study the evolution of "timidity" of the prey (i.e., its readiness to seek refuge) in a predator-prey model with the DeAngelis-Beddington functional response. Using the theory of adaptive dynamics, we find that a predator-prey population at equilibrium always favours less timidity. Low levels of timidity, however, may destabilize the population and lead to cycles. Large-amplitude cycles favour a positive level of timidity, but if such cycles do not occur, timidity will evolve all the way to zero, where the prey no longer responds to the predator by seeking refuge, and in which case the DeAngelis--Beddington functional response has become identical to the Holling type-II functional response.
报告（四）
题 目：Mechanistic population models: what are they, and why are they important?
时 间：2014年7月7日（周一）， 上午9：00～11：00
地 点：理科楼202
摘 要：A model is an equation with an interpretation. A population model in which all parameters have an interpretation in terms of the behavior of the individual is called a "mechanistic population model". The behaviour of the individuals that result in a particular structure and behaviour of the population is called the underlying mechanism of the model. Using examples, we show that the same population equation can have different underlying mechanisms. We also show that the underlying mechanism can affect the qualitative behaviour of the dynamics in different ways for alternative mechanism if the model becomes subject to environmental or demographic noise or time-delays.
报告人简介：Stefan A.H. Geritz是芬兰赫尔辛基大学（University of Helsinki）数学与统计系教授。主要研究领域是生物数学，特别是适应动力学理论及其在生态系统和传染病中的应用。Stefan A.H. Geritz教授是适应动力学理论的共同创始人之一，共发表了30多篇论文，总的引用次数为2295次，H-指数是18，其中他们发表的2篇论文 (Metz et al. 1992; Geritz et al. 1998) 目前已被引用528次和645次。他目前也是“Theory in Biosciences (Elsevier)”等杂志的编委。
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