Pheromones intrinsic factors

Gleeson RA (1991) Intrinsic factors mediating pheromone communication in the blue crab, Callinectes sapidus. In Martin JW, Bauer RT (eds) Crustacean sexual biology. Columbia University Press, New York... 

Intrinsic and Extrinsic Factors. We propose that the evolution of hormonal pheromones is affected by two fundamentally different factors intrinsic and extrinsic. Intrinsic factors are exclusively associated with interactions between or among conspecifics (i.e. intrinsic to a species pheromonal functions), and would include aspects such as the rate and mode of release of hormonal products by donors, and the sensitivity and specificity with which these products are detected by receivers. Thus, intrinsic factors are directly associated with the origins and continued existence of hormonal pheromones and are subject to evolutionary feedback as a consequence of their actions. 

Once spying is established, further specialization may be restricted to the receiver (Section 5.3.1.2), but this need not always be the case. In particular, if the donor of a pheromone benefits from the receiver s response to it, then the donor may come to develop specializations which optimize pheromone production. The latter relationship we term communication and the specialized products associated with it, signals (Figure 1 Stacey and Sorensen, 1991). Because communication involves co-evolution and specialization of both donor and receiver, it likely is influenced by intrinsic factors different than those that affect spying we therefore discuss intrinsic factors and spying (Section 5.3.1) separately from intrinsic factors and communication (Section 5.3.2). In contrast, spying and communication are both influenced by similar types of extrinsic factors as they are... 

Figure 2. A schematic representation of the influences of intrinsic factors on spying. The top fish in each pair is the donor, shown releasing an array of hormonal products (A-E). The bottom fish in each pair is the receiver. Above the receiver, a horizontal dashed line indicates no olfactory receptor is present for a hormonal product, a filled circle indicates a receptor is present, and an empty circle indicates an olfactory receptor has been recently expressed. Spying evolves when a receiver comes to detect a hormonal product (now termed a pheromonal cue) released by a conspecific donor and benefits from doing so. Most likely, the process starts with development of sensitivity to a single cue but may rapidly expand to include a mixture of compounds, the phenomenon we term, cue elaboration. Pheromonal mixtures will be subject to modification by extrinsic factors. Also they may come to serve a communicatory function (and thus be susceptible to a different suite of pressures) if the pheromone donor comes to benefit directly from releasing the cue.

How Stable Are Hormonal Pheromone Systems Which Employ Specialized Signals Because of the high level of co-evolution and specialization associated with the development of sexual signals, we believe that intrinsic factors promote elaboration of pheromonal complexity, but also make communication systems relatively immune to fundamental change. Change is more likely to result from extrinsic factors as discussed below (Section 5.4). 

The sexual response of adult males depends on both intrinsic and environmental factors. Males become responsive to the pheromone 6-9 days after adult emergence (Wharton et al, 1954 Hawkins and Rust, 1977). Antennation and erect body posture appear at the same hme during sexual maturation, followed by, in this order, increased locomotion, running, wing-raising, and abdominal extension (Silverman,... 

It is apparent from the sheer length of this review that hormonal pheromones may evolve in many directions according to a wide variety of intrinsic and extrinsic factors, the nature of which are as yet poorly understood. A common theme appears to be that these systems might be much more dynamic than presently recognized and that multiple component mixtures are likely to be commonly employed. Research now needs to be conducted to address these possibilities. 

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