Bondar - Wild Sex

To my Mom

Human females are certainly influenced by the crooning abilities of our male counterparts. A sexy radio voice or a beautiful song can seduce us even without a visual signal to match it. Like many other sexual characteristics across a wide range of species, a males vocalizations are a means by which to gain access to females. Many females rely on a males song to gain information about his biological fitness, and they may be doing so without laying eyes on him. As with any kind of sexual ornament, a song has both easy and difficult aspects to its production and it is the difficult aspects that separate the men from the boys. In other words, anyone can tweet out Row-Row-Row Your Boat, but what about a stunning rendition of Beethovens Fifth? Songbird females can judge a male on the length, dialect, repertoire and complexity of his songs. Even the consistency in the reproduction of similar notes, or a songs trill (where a single syllable is repeated in quick succession) is up for adjudication. Bachelor-birds generally sing different songs than those already paired with a female (you can insert your own joke here about the sad song of a saddled-down guy). This makes a lot of sense because a male who has yet to find a mate has a completely different set of signalling priorities than one who is presently spoken for. Presently is the key word, because in most socially monogamous bird species, extra-pair copulations are the rule rather than the exception. This means that males of several bird species are constantly changing their tune depending on whether they are at home with the old lady or whether they are out looking for a one-night stand.

In addition to creating mating calls alone, some bird species engage in a calling behaviour termed duetting. This generally takes place in socially monogamous species, and is thought to function in demonstrating pair commitment. Duetting couples use distinct song codes to signal exclusively to each other, perhaps akin to the pet names or words that human couples share. It makes sense that such a couple-specific signal would serve to strengthen the pair bond in duetting birds, although there remains much debate about its biological significance, especially in light of the high incidence of extra-pair copulations that I mentioned above.

Birds are not the only organisms to utilize the sexual power of song. In fact the sheer complexity of songs utilized by organisms like amphibians and insects is astonishing. Male Emei music frogs (Babina daunchina) build small burrows at the edges of ponds where the female lays her eggs. The male tends to the fertilized eggs until they are tadpoles, and this again takes place within his burrow. Just how does a male attract a potential female partner? With song. Males produce courtship songs from both inside and outside of their burrows, although females have been shown to prefer calls that emanate from within. This is probably due to the fact that important information about the burrow can be gained from the acoustic properties of the songs. Its crucial for a female to evaluate both the male himself and the kinds of resources hes bringing to the table, including the area and depth of the burrow where she will make her ever-important genetic deposit. Male tree-hole frogs exhibit a similar level of acoustic prowess. They demonstrate the power of song by exploiting the properties of the tree-trunk cavities in which they nest. The cavities tend to be partially filled with water, which creates variation in the acoustics that result from a certain call frequency. Males will begin calling to potential female mates with a ranging pitch, but once they hit the frequency that results in maximum amplitude of their signal, they keep their calls steady. In this way, they maximize their chances of attracting a mate.

A great number of organisms across the animal kingdom can be thankful for the chemical processes that bring them reproductive success. The power of olfaction (smell) is extremely important for a multitude of biological processes including predation, resource collection and of course finding a mate. Minute changes in the chemical signatures of various secretions can transform their ecological meanings. Although we Homo sapiens are not without natural signals of sexual chemistry (pheromones), we unfortunately spend a lot of time and effort clearing them away. Humans are under the incorrect impression that our natural scents are somehow dirty and unwelcome. We scrub our bodies with soaps and shampoos, and we use deodorants and perfumes and other unnatural chemicals to hide away what comes naturally. What people neglect to realize is that chemical cues are widespread, used by creatures from massive mammals to microscopic invertebrates, and for the most part they serve to bring receptive parties to the sexual arena. Many courtship pheromones have evolved for maximum efficiencies in both energy expenditure and gamete allocation. In other words, the chemical signals emitted by bachelorette #1 may be superior to those of bachelorette #2, resulting in a greater sperm allocation to the former. Imagine if you could identify an appropriate mate by simply smelling them.

The sheer diversity in the strategies of sexual chemistry is mind-blowing. There is a wide spectrum of approaches to sex via chemical help, from organisms who broadcast spawn (and therefore use chemical signals to ensure that their gametes are going to reach those of other members of their own species) to those that use a suite of chemical cues to maximize reproductive selfishness or to lure unsuspecting sexual victims.

We can generalize that male animals secrete chemical pheromones to attract females (and vice versa). This happens in many different scenarios and environments, both terrestrial and aquatic. A key issue for any particular male attempting to lure a female is that hed prefer it if said female was only interested in his sperm. If a female is lured by the scent of a particular male, whats stopping her from being lured by the next, then the next, and so on? Evolution has dealt males a few distinct methods to deal with the problems that could arise in such a scenario. Not only do many males produce pheromonal cues to attract females (virgin females in many cases), they also produce chemical cues that cause a reduced or completely diminished response in the female once they have made their genetic deposit. Properties of oral secretions or ejaculates in diverse creatures show that anti-aphrodisiac pheromones often serve the purpose of redirecting a females attention after mating. Essentially, such pheromones serve to enforce monogamy and to ensure paternity of resulting offspring. There are cases where this makes evolutionary sense for both males and females, such as when females receive all the sperm that they require from one sexual encounter and they can then turn their energetic attentions elsewhere. Males also produce and transfer pheromones to females that serve to decrease her attractiveness to other males. Again, this could be advantageous to females that aim to avoid harassment from unwelcome suitors, but this is certainly not always the case.

What happens when females are interested in additional copulations for increased genetic diversity in their offspring? What if she has been coerced into mating by a low-quality male? In these scenarios it does not make sense for a female to be put out of reproductive action by an anti-aphrodisiac or a pheromone that makes her ugly to other males. Indeed, in many invertebrate species there is evidence for chemical arms races where females have evolved resistance to male-generated anti-aphrodisiacs, which then evolve to compensate for these physiological changes and so on. Such biochemical warfare is complicated and extremely difficult to decipher.