Species diversification

Ordovician 500 Myr Diversification of echinoderms, other invertebrate phyla, jawless fishes. Mass extinction at end of period (ca. 85To of all species disappear)... 

Protein dephosphorylation is catalyzed by phospho-hydrolases called protein phosphatases. While the number of protein tyrosine kinases is roughly comparable to the number of protein tyrosine phosphatases, protein serine-threonine kinases vastly outnumber the protein serine-threonine phosphatases, of which about 25 different species are known to exist. This relative under-representation may be accounted for by the alternative diversification... 

Multicomponent reaction systems are highly valued in solid-phase organic synthesis because several elements of diversity can be introduced in a single transformation.1 The Mannich reaction is a classic example of a three-component system in which an active hydrogen component, such as a terminal alkyne, undergoes condensation with the putative imine species formed from the condensation of an amine with an aldehyde.2 The resultant Mannich adducts contain at least three potential sites for diversification specifically, each individual component—the amine, aldehyde, and alkyne—can be varied in structure and thus provide an element of diversity. 

Diversification of structure of glycosides often accompanies coradiation of pi ant and herbivore species. 

We may hypothesize for the present that columnar cacti produce alkaloids as a general deterrent to herbivory, and triterpenoid glycosides and associated hydrolytic glycosidases as a specific toxification mechanism against specialist Drosophila species. Radiation and diversification of triterpenoids may have occurred in response to continued interaction between the cacti and Drosophila This process is dependent upon coevolution with specialized yeasts which may interfere with hydrolysis of triterpenoids or hydrolyze individual compounds selectively. 

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. 

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. 

One of the hypotheses regarding evolutionary aspects of flavonoid diversification concerns the concept of flavonol accumulation in basal Angiosperms versus flavone accumulation in advanced families. Recently, some further efforts have been made towards defining the flavone/flavonols ratio in Dicotyledonae and their relation to lignification, indicating an increased tendency towards flavonol accumulation in lignified plants, whereas herbaceous species tend to accumulate more of the flavones. From the presented entries, it appears that flavone derivatives are more abundant in Lamiaceae than flavonols. In the Asteraceae, however, more data concern the flavonols. Both families are more or less herbaceous and members of the more advanced Angiosperms. 

Another example of pheromone diversification occurs in the larch budmoth, Zeiraphera diniana, complex. The two species use ( )-9- and (E)- 1-tetradecenyl acetates as a pheromone, the larch-feeding type in a 100 1 ratio and the pine-feeding... 

The focus of the chapter has been antibody diversification in humans and mice, the species that have been most thoroughly studied for the longest time. However, in the last several years it has become clear that, although the principal features of antibody diversification are shared by all vertebrates, the specifics can vary considerably from one species to another, even within the class of mammals. Evolution may achieve workable solutions in a variety of ways, none necessarily optimal." Among the tasks of the next few years will be exploration of the limits of this variation. 

Kohn MJ, Fremd TJ (2007) Tectonic controls on isotope compositions and species diversification, John Day Basin, central Oregon. PaleoBios (in press)... 

Stanhope, M.J., Hartwick, B., and Baillie, D., Molecular phylogeographic evidence for multiple shifts in habitat preference in the diversification of an amphipod species, Mol. Ecol., 2, 99, 1993. 

The most prominent examples of pheromone diversification are found in Noctuidae. The sex pheromones of the Noctuidae species are mixtures of at least three compounds that differ mainly in carbon chain length (Lofstedt et al., 1982 Teal... 

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