Coevolution of plants and insects

I will extend this argument to encompass the diversification of such systems in lineages of plants in an effort to correlate enzyme-mediated glycoside toxicity with the evolution of host plant specificity and the coevolution of plants and insects. 

The coevolution of plants and insects, birds and bats with respect to the pollination of flowers gave rise to the formation of special morphological features and chemical characteristics. The main reason why pollinators visit flowers is to gather nectar and pollen as nutrients which contain carbohydrates, fats, and proteins. With respect to secondary products... 

Life in the oceans differs in most respects from life on land. The most remarkable observation is that the oceans are poorer in species but richer in phyla with respect to land (Chapter 1.2). This finds no easy answer, however. Perhaps the reason for the larger number of species on land lies in a wider diversification of habitat and climate than in the sea, which required a great deal of adaptation, accompanied by speciation. In these affairs, coevolution of plants with insects was a major trigger of biodiversity. 

This coevolution between plants and animals for their mutual benefit has not only resulted in the complex and individual fragrances that they produce but in the wonderful color and structure of flowers themselves. We do not know whether insects such as bees can smell precisely the same range of materials as ourselves or whether their olfactory world differs from ours in the same way as does their vision. Bees are able to "see" ultraviolet, and the patterns of flowers that guide the bee toward the source of food appear quite different to the bee than they do to us. But, since we are able to smell most constituents of essential oils, it is probably fair to assume that our range of smell is quite similar. Perhaps bees have a much clearer idea of the smell of benzyl alcohol, which occurs in many flowers, than do most perfumers. How it would actually smell to them we cannot imagine any more than we can imagine the color of ultraviolet. 

The coevolution of plants with the bacteria, fungi, insects, nematodes, viruses, and others that attack them has led to... 

Rothschild, M., Carotenoids in the evolution of signals. Experiments with insects (1974-1976), in Biochemical Aspects of Plant and Animal Coevolution (J. B. Harborne, ed.), 259-276, Academic Press, New York, 1978. 

McNeil, S. and Southwood, T. R. E. (1978) The role of nitrogen in the development of insect plant relationships. In Biochemical Aspects of Plant and Animal Coevolution (Harborne, J. B., ed.) pp. 77-98. Academic Press, London. 

Feeny, P. P. (1975) Biochemical coevolution between plants and their insect herbivores. In Coevolution of Animals and Plants (Gilbert, L. E. and Raven, P. R., eds) pp. 3-19. University of Texas Press, Austin. 

Glycoside diversification also has occurred in the coevolution of monarch butterflies and milkweeds (7). It may be desirable to relate the toxicity of cardenolides to the hydrolytic capabilities of susceptible and nonsusceptible insects. Cardenolides from Rsclepias species can be hydrolyzed by 3-glucosidases present in the plant (6), yet specialized Danans species are able to sequester these compounds, a process wh ich requires control of hydrolysis. 

In order to understand fully the importance of these chemical factors, it is necessary to consider the processes which are probably responsible for their diversification. A mechanism of coevolution of insects and plants was set forth eloquently by Erlich and Raven (4). According to their hypothesis, angiosperms produced a series of chemical compounds which were not directly related to their basic (or primary) metabolic pathways, but which were otherwise not harmful to the plants growth and development. 

Evans HC. Co-evolution of entomogenous fungi and their insect hosts. In Pirozynski KA, Hawksworth DL, eds. Coevolution of Fungi with Plants and Animals. London, New York Academic Press, 1988, pp 149-171. 

An improved knowledge of the monoterpenoids (as well as sesquiterpenes, diterpenes, triterpenes, tetraterpenes) and their effects on insects contributes to unraveling the intricate interactions that have shaped the coevolution of insects and plants. It also provides leads for possible utility of these safe, degradable compounds in modern pest control, and, as more advanced genetic engineering capabilities develop, the potential for... 

Bowers, M. D., Chemistry and coevolution Iridoid glycosides, plants, and herbivorous insects, in Chemical Mediation of Coevolution (K. C. Spencer, ed.), 133-165, Academic Press, San Diego, CA, 1988. 

The process of coevolution of the plant and the predatory insect may be either simple or complicated. A rather simple case would be as follows A species of plant is broadly distributed, it has a spectrum of predators, and a balanced system exists. The number of herbivorous insects developed on... 

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. 

Such a strong impact on survivorship or fecundity, and on the fitness of individuals, means exerting strong natural selection on herbivorous insects. This should favor the rapid evolution of insect adaptations which overcome it. This is, of course, a common occurrence in the application of pesticides or the development of resistant crop plant cultivars (11). The supposition that plant defenses select for detoxication adaptations in insects is the foundation of the concept of coevolution (12). 

---