91社区

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Adaptive and Non-Adaptive Dynamics

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Gregor Fussmann

Department of Biology, 91社区

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The dogma in evolutionary biology is that the characters of organisms change over time in a way that increases organisms鈥� fitness. This process has been graphically compared with (and mathematically analyzed as) 鈥渃limbing an adaptive hill.鈥� There are many empirical examples for this adaptive view of evolution 鈥� particularly from experimental evolution studies in the laboratory. More recent, critical inspection of results reveals that there are also a large number of counter examples (mostly from natural environments), where organismal traits change without affording any apparent increase in fitness.

I present some examples of adaptive and non-adaptive change from my own experimental studies. I then present a simple mathematical model that might explain why we often observe non-adaptive states in nature. The solution evokes transient evolutionary dynamics that pass through non-adaptive states before they reach their final adaptive endpoint.