Evolutionary considerations

Reproductive pheromones are powerful isolating agents between species, as is well known for insects such as moths and drosophilas (Wyatt, 2003). 

Males and females of the North American slimy salamander Pkthodon glutinosus prefer substrates previously occupied by a conspecific over their own, but they do not discriminate between the sexes. However, in an olfactometer with live salamanders as odor source, male and female P. glutinosus, male Fkthodonjordani, and a related phenotype ( species A ) all preferred female over male odors. Male P. glutinosus and species A chose conspecific over heterospecific female odors in the olfactometer. This indicates that airborne odors may constitute an important pre-mating isolation mechanism (Dawley, 1984). 

Red-sided garter snakes from different regions of Manitoba, Canada show signs of isolation by chemical cues. In choice tests, males from a hiber-naculum (overwintering den) in central Manitoba preferred females from their own population to females from western Manitoba. Males from western Manitoba showed no preference. When confronted with experimental trails, males made the same choices. This demonstrated that a chemical factor is involved. Furthermore, the sexual attractiveness pheromone of females, a series of ty-9-cis-unsaturated methyl ketones, varies between the populations. Specifically, the 

Discrimination of species odors, and hy inference, reproductive isolation between species by means of odors, has been demonstrated for many species. Early examples are bank voles, Ckthrionomysglareolus (Godfrey, 1958), Peromyscus spp. (Moore, 1965 Doty, 1972),M sspp. (Bowers and Alexander, 1967), andger-bils (Dagg and Windsor, 1971). Male naked mole rats (superspecies Spalax ehren-hergi, Spalacidae) preferred odors from estrous females of their own to a different karyotype in a two-choice apparatus. The odors used were those of soiled bedding and urine from females (Nevo etah, 1976). 

Odors - as any other body features or social signals - are both product and agent of evolutionary processes. Are there extreme results of runaway evolution As such examples are not immediately accessible to our senses, we have yet to discover the olfactory equivalents of the bizarre Irish elk s antlers, the wings of the Argus pheasant, or the antics of the bowerbirds. 

In the evolution of the immunoglobulin superfamily (Fig. 12) three critical steps can be discerned (1) the assembly of the primordial V unit. According to one hypothesis [201], the primordial building block was a unit half the size of present day 

V units, with a high propensity to self-assemble into a stable, symmetric dimer. This hypothesis derives from the observation of a highly symmetrical topology in 

V units and is supported by the findings that the CD4 V unit coding sequence is split into two halves by an intron [163] and that the squid Thy-l-like molecule is homologous to a half-unit [187]. In a different theory, the V domain may have re- 

C04 poly. Ig receptor IgG FcR Thy-1 MRC OX-2 MHC CD1 molecules molecules T cell receptors 

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Powell, A. M. and Guppy, C. S. 1988b. Evolutionary considerations based on... 

Behnke, J.M., Barnard, C.J. and Wakelin, D. (1992) Understanding chronic nematode infections evolutionary considerations, current hypotheses, and the way forward. Internationalfoumal for Parasitology 22, 861-907. 

This is perhaps one of the most neglected emotions, being absent from most psychologists lists. No other omission better illustrates the folly of ignoring evolutionary considerations in drawing up lists of emotions. 

Broda E, Peschek GA. 1980. Evolutionary considerations on the thermodynamics of nitrogen fixation. Biosystems 13 47-56. 

Chapter 6 discussed signaling pheromones that allow discrimination, recognition, and broadcasting dominance and territorial status. This chapter explores the role of pheromones and other odors in reproduction, alarm, trail following, and in connection with food. Some evolutionary considerations conclude the discussion of signaling pheromones. 

Klrsch, J.F. Eliot, A.C. (2004) Pyridoxal phosphate enzymes mechanistic, structural and evolutionary considerations. Annu. 

A number of studies have been performed in the context of a theory that proteins and polynucleotides were formal in a suspension of proteinoid microspheres and the microspheres could then have evolved to contemporary cells. The experimental results and evolutionary considerations have been summarized in the textbook of Fox and Dose published in 1977 2). This review therefore deals with studies since 1977, although some description of literature before 1977 is reviewed as occasion demands. Since the evolutionary consideration of proteinoids and proteinoid micro-spheres has been discussed in much literature and many books, (e.g. 2, 3), the attention in this paper is focussed on the description of the biochemical and experimental parts of the literature. Inasmuch as protobiological activities of proteinoids in solution are carried into microspheres 2), experiments with proteinoids in solution are not excluded. 

Evolutionary considerations of nitrogen metabolism and excretion. In Fish Physiology, Vol. 18, pp. 1-16, ed. P.M. Anderson and P.A. Wright. New York Academic Press. 

McLennan S. M., BockB., HemmingS. R., Hurowitz J. A., Lev S. M., and McDaniel D. K. (2003) The roles of provenance and sedimentary processes in the geochemistry of sedimentary rocks. In Geochemistry of Sediments and Sedimentary Rocks Evolutionary Considerations to Mineral Deposit-Forming Environments, (ed. D. R. Lentz), Geol. Assoc. Canada GEOtext. St. John s, Nfld, vol. 5, pp. 1-31. 

Eliot, A. C... and Kirsch, J F. 2004 Pyridoxal phosphate cnzvmcs Vlechanistic, structural, and evolutionary considerations.. Imiii. Rev. Biochem. 73 38.1-41.5. 

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