Arms race

May. The nuclear arms race ends—for the first time since 1945, the United States builds no nuclear weapons. 

Harbome, J.R. (1993). Introduction to Ecological Biochemistry, 4th edition—A very popular text that contains chapters on the toxic compounds of plants and the coevolutionary arms race. 

The role of antiproliferative effects of an activated defense reducing the next generation of herbivores compared with the straightforward action of toxins or feeding deterrent metabolites in the evolutionary arms race is still under discussion. The proposed mechanism suggests natural selection at the group level,... 

A one-page essay in which it is suggested that evolution in plankton is driven by a watery arms race has attracted much attention (Smetacek 2001). Smetacek discusses the concept that defence of phytoplankton by mechanical protection, increased cell size, formation of spines, or production of noxious chemicals leads to the adaptation of zooplankton to these measures. This process resulted in the shape and properties of phyto- and zooplankton that we observe today. In the years following that essay several candidate molecules were discovered and intensely studied. The concept that chemical signals and defence metabolites are important factors in plankton ecology has now become widely accepted. 

Maor R, Shrrasu K (2005) The arms race continues battle strategies between plants and fungal pathogens. Curr Opin Microbiol 8 399... 

Plant-Pathogen Interactions A Never-Ending Arms Race... 

Coevolution is defined as reciprocal stepwise adaptations between at least two species (Ehrlich and Raven, 1964). Coevolution without the criterion of reciprocity is indistinguishable from evolution and hence a useless concept (Lindroth, 1988). Consider the following scenario. A plant develops effective antiherbivore defenses. In response, a herbivore counteradapts to circumvent these defenses and is at a competitive advantage over other herbivores. The plant, in turn, responds to this breach of its defenses. In insects, such pairwise reciprocal evolution can take the form of a chemical arms race (Dawkins and Krebs, 1979). Coevolution differs from evolution by being narrower, with fewer participants, perhaps even only two species or two populations. In reality, in most ecosystems, many species prey on many other species. Therefore, we can at best speak of diffuse coevolution, with a number of participants that exert diluted selection pressures. 

Dawkins, R. and Krebs, J. R. (1979). Arms races between and within species. Proceedings of the Royal Society of London Series B 205,489-511. 

Berenbaum, M. R. and Feeny, P. P. 1981. Toxicify of angular furanocoumarins to swallowtail butterflies escalation in a coevolutionary arms race Science, 212 927-929. 

These speculations provide some possible reasons why the low frequency of occurrence of antibiotics in microbes cannot be used as a conclusive argument that microbes must have evolved NTs to serve a role other than competing with each other. Could it be that the term chemical arms race often used when discussing NP evolution is really less appropriate than economic arms race ... 

The establishment of plant integrated defenses involves the preferential evolutionary retention and production of those SCs exerting synergistic toxic effects and is possible only if a diversification of secondary metabolism in a given plant has previously occurred. This preliminary diversification of secondary metabolism could be mediated via the classical reciprocal co-evolutionary interactions between a host plant and its major pests, as predicted by the chemical arms race model (Beren-baum and Zangerl, 1996). The PICD hypothesis is consequently not an exclusive evolutionary hypothesis because it is compatible with and dependent on other evolutionary processes. The contribution of the PICD hypothesis is to provide both a functional explanation for the diversity of SCs within plants (Romeo et al, 1996) and a reconciliation between different evolutionary models. 

Plant integrated chemical defenses comparisons with chemical arms race model... 

These considerations regarding the major differences between the chemical arms race model and the PICD hypothesis are summarized in Table 1.2. It is suggested that... 

Table 1.2. Differences between the chemical arms race and the integrated chemical defenses hypotheses...

Chemical arms race Integrated chemical defense... 

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