Sexual behavior courtship

These cues are important in rearing, territorial, courtship and, in particular, sexual behaviors. The vomeronasal organ (VNO) is separate from the main epithelium in mammals, comprising a thin epithelial tissue within a bony capsule in the lateral wall of the nasal cavity. It is probably vestigial in humans. The VNO epithelium contains at least two populations of microvillar chemosensory neurons one is in the more apical aspects of the epithelium, while the other lies in the more basal region. These two populations of vomeronasal neurons (VNs) are defined by the differential expression of several genes. For example, the apical VNs express the G-protein subunit Ga, while the basal neurons express Ga0. Apical and basal VNs also... 

Chemical cues are important to advertise one s sex and to attract the opposite sex as the first step in sexual behavior. Other functions of sexual signals are to signal current sexual status and to alter the behavior of the potential partner(s) via courtship or scent marking to facilitate mating. Typically, the odor of the opposite sex is attractive, at least in the breeding season. (Priming pheromones are covered separately in Chapter 8.)... 

An important step toward the correct identification of the sex pheromone of P. americana was the identification of several phytochemicals, such as bomyl acetate and santalol, that stimulated courtship behavior in males (Bowers and Bodenstein, 1971 see p. 196). Some years later, Tahara etal. (1975) and Kitamuta et al. (1976) reported that germacrene-D, extracted from composite plant species, stimulated sexual behavior in males of P. americana and the Japanese cockroach Periplaneta japonica Karny. Persoons etal. (1974, 1976) determined, on the basis... 

In the screw-worm fly (Cochliomyia hominivorax), courtship is generally very brief as a result, bioassays are generally based on male copulation levels (Hammack, 1986). Some CHCs show different levels between the sexes and are thought to be involved in courtship and mating (Pomonis, 1989). Similarly, in Lucilia cuprina, CHCs are thought to play a role in sexual behavior, but decisive evidence has yet to be produced (Emmens, 1981). 

The long chain CHCs (27-35C) are similar on the cuticle of immature male and female flies of the D. melanogaster and D. virilis group of species (Pechine et al., 1985,1988). In D. melanogaster, mature CHCs have completely replaced the immature compounds on the fly cuticle after 36 hours (Antony and Jallon, 1982). The maturation of CHCs corresponds to the maturation of sexual behavior, but each maturation process is under separate genetic control desatl for CH production (Marcillac et al., 2005a) and prospero for male courtship maturation (Grosjean et al., 2007). 

In addition to the ability to differentiate between sexual behaviors (e.g., courtship display) and signals (e.g., food attractants), it is important to employ a receiver that is physiologically and hormonally receptive to a sender s pheromone (Hayden et al. 2007). Most animals live in complex chemical environments and an individual simultaneously detects multiple chemical signals from a variety of sources (Hazlett 1999, this volume), such as living and dead conspecifics, predators, competitors,... 

Moore, F.L., McCormack, C. and Swanson, L. 1979. Induced ovulation effects of sexual behavior and insemination on ovulation and progesterone levels in Taricha granulosa. Gen. and Comp. Endocrinol., 39, 262—269. Noble, G.K. 1937. The sense organs involved in the courtship of Storeria, Thamnophis, and other snakes. Bull. Am. Mus. Nat. Hist., 73, 61 A—125. 

When a courtship response is used as an indicator of pheromone sensitivity, the failure of immature animals to respond may be a reflection of a reduced state of sexual motivation rather than an inability to detect pheromonal odors. In a wide variety of male and female teleosts, sufficient levels of circulating sex steroids are required before sexual behavior is expressed (Liley and Stacey, 1983). The sex steroid concentrating areas of the ventral telencephalon and preoptic area are thought to mediate this effect by controlling behavioral output, a function distinct from their possible role in the detection of pheromones per se (see discussions in Kyle and Peter, 1982 Kyle et al., 1982 Demski and Hornby, 1982). 

Snakes, as a group, are visually cryptic and auditorially impoverished. Therefore, it is probable that chemical cues are quite important in mate location. The utilization of pheromone trails in the reproductive activity of snakes has been examined to some extent in temperate zone colubrids. In these snakes, sexual behavior occurs primarily in the spring. Males leave the hibernacula first and remain in the vicinity to court the females when they emerge. At this time, female snakes leave trails for the males to follow. The pheromone involved is likely the same lipoprotein (vitellogenin) which the females produce in the liver and secrete through the skin to stimulate male courtship activity (Garstka and Crews, 1981, this volume), although the only evidence for this is that the sexual pheromone trails are also produced by skin secretions and, like a lipoprotein, are non-volatile and persistent (Ford and Low, 1984). 

Females of the desert spider Agenelopsis aperta emit a volatile pheromone that attracts conspecihc males (Riechert and Singer, 1995). This pheromone was identified as 8-methyl-2-nonanone (1 Fig. 4.1), a previously unknown arthropod semio-chemical. It was found by headspace analysis and abdominal washings of females 2 weeks after their hnal molt, when they become sexually receptive it was absent in females of other age classes. The pheromone attracted males in a three-choice arena system at doses as low as 500 ng (Papke et al., 2001). Another female-specific ketone, 6-methyl-3-heptanone (2), was not attractive. Very low doses of 1 (10-9 mg/ml applied to a hlter paper placed in empty juvenile female webs) also induced courtship behavior in males (Papke et al., 2001). The normal behavioral sequence was followed, except for phases which required input from the female. The ED50 value (mean effective dose) of 1 was 5.5x 10-4 mg/ml hexane. In contrast, ketone 2 only induced a response in some males at unnaturally high concentrations... 

As in B. germanica, newly molted males and nymphs elicit wing-raising courtship responses from sexually mature N. cinerea males (Fukui and Takahashi, 1983, 1999 Schal and Bell, 1983). It seems that all individuals, when newly molted, can stimulate male courtship, and that males and nymphs, but not females, produce secondary compounds as they age that reduce this effect. A compound that inhibits male courtship was identified from older nymphs as cis-25,26-epoxyhenpentacontadiene (Fukui and Takahashi, 1999). Whether there is an adaptive advantage for nymphs to stimulate courtship soon after the molt and later inhibit this behavior in mature males is not clear. It is possible that by mimicking females teneral cockroaches are better protected from aggressive males, but this has not been demonstrated. 

Cobb M., Burnet B. and Connolly K. (1988) Sexual isolation and courtship behavior in Drosophila simulans, D. mauritiana, and their interspecific hybrids. Behav. Genet. 18, 211-225. 

Oguma Y., Jallon J. M., Tomaru M. and Matsubayashi H. (1996) Courtship behavior and sexual isolation between Drosophila auraria and D. triauraria in darkness and light. J. Evol. Biol. 9, 803-815. 

First, a correlation was found between the occurrence, latency and duration of a series of male behaviors and the absolute and relative levels of some CHCs. Latency to initiate courtship (orientation and tapping) was inversely related to the amount of 5-T. This relatively volatile CHC is produced mainly - but not exclusively - by males and may increase female receptivity in some strains. Males of some Zimbabwean strains produce more 5-T than cosmopolitan males (Grillet et al., unpublished data). Female flies from Zimbabwe show a strong sexual discrimination against cosmopolitan males (e.g. Wu et al., 1995), but it is not yet clear whether 5-T is involved in this strong intraspecific sexual isolation. 

In the tse-tse fly (Glossina tachinoides) courtship is very brief and difficult to characterize. First, the male uses visual cues to recognize a potential conspecific partner. Then, several pheromonal components carried by flies of both sexes seem to reciprocally facilitate sexual receptivity whereas other molecules are required for successful mating. When placed on solvent-washed dummies, biological doses of synthetic 11,23-, and (to a lesser extent) of 13,25-dimethylheptatriacontane elicit most of the behaviors normally induced by a female (Carlson et al., 1978 El Messoussi et al., 1994 Carlson et al., 1998). In G. austeni, the... 

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