Chemical signals population variation

Variations in sex-specific population densities, e.g., due to extraction by fisheries, may also affect the dynamics of chemical communication in crustaceans (e.g., van Son and Thiel 2007). At low population densities, members from the mate-attracting sex may have to invest more in chemical advertisement than at high densities. On the other hand, individuals from the mate-searching sex that are efficient and rapid in responding to chemical signals may be at an advantage at low population densities. 

Critical investigations are just beginning, but analyses of salamander courtship pheromones potentially can offer compelling insights at the population level into sources of individual variation in reproductive success. At another level, these pheromones are candidates for examining predictions of sexual selection theory. At either level, the taxonomic variety and evolutionary persistence of courtship pheromone delivery in salamanders is a testimony to the reproductive significance of these chemical signals. 

Temporal Variation of Ion Signal of an Inert Ion. 1. Problem Definition Several assumptions are required if correct correlations between ion signal and chemical reactivity are to be made from ion kinetic studies using FTMS. The first assumption must be that the sensitivity of the ion trap remains constant with time so that ion signals are representative of the ion population with time. The second assumption is that losses of reactant ions are due to consumption of those ions in a chemical reaction and not by physical processes. 

Another technique that is specific for radical processes is known as CK)NP, an abbreviation for chemically induced dynamic nuclear polarization The instrumentation required for such studies is an NMR spectrometer. CIDNP is observed as a strong perturbation of the intensity of NMR signals in products formed in certain types of free radical reactions. The variation in intensity results when the normal population of... 

---