NPs and animal behaviour

Living creatures use, metabolically, a very wide range of chemicals but NPs are not significant in this respect. The reason why NPs were once considered secondary (Chapters 1, 5 and 9) was because an individual in a population can survive in the short term when it is not making, or accessing, NPs. However, it has been established that while individuals can survive without NPs, individuals that have evolved to make or sense NPs are fitter. Why might that be  

In summary, every organism making NPs has a much smaller number of potential target proteins available to it than one might initially expect. However, it is inevitable that, just by chance, some organisms will make the occasional NP that has a potent ability to bind to some protein in an organism with which it never interacts. Such fortuitous interactions will be selectively unimportant to the producer of the NPs as they do not add or detract direcdy from the fitness of the producer.  

With this short general introduction to the chapter behind us, it is time to look more closely at some specific interactions that involve NPs. Given that NPs evolved in microbes, it is necessary to start our analysis with those organisms, despite the fact that the interaction between microbes has been subject to much less attention than the interactions of higher organisms. 

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