A courtship display is a set of behaviors in which an animal attempts to attract a mate and exhibit their desire to copulate. These behaviors often include ritualized movement ("dances"), vocalizations, mechanical sound production, or displays of beauty, strength, or agonistic ability.
In general, males are often the sex which initiate courtship displays in response to pre-copulatory sexual selection. Performing a display allows the male to present his traits or abilities to a female. Mate choice, in this context, is driven by females. Direct or indirect benefits are often key deciding factors in which males get to copulate and which don't.
Direct benefits can be seen due to the expression of preference. Females can raise their own fitness if they prefer to respond to particular types of signals, independent of costs and certain benefits associated with mating. For example, choosing to mate with males that produce more localized signals would incur less of an energetic investment for a female as she searches for a mate. On the other hand, females can put in more energy towards this process and still attain a higher fitness if they mate with only particular types of males. With this, the males being chosen may impose lower costs on the female or even provide more in terms of material or offspring contributions.
Indirect benefits are benefits that may not directly affect the parents' fitness. As such, indirect benefits increase the fitness of the offspring. For example, offspring of a female will inherit half of the genetic information from the male counterpart. This means that those traits she saw as attractive will be passed on, producing an offspring that is more fit.
The male Six-Plumed bird-of-paradise, Parotia lawesii, exemplifies this idea of male courtship display with its ritualized "ballerina dance" and unique occipital and breast feathers that serve to stimulate the female visual system. This stimulation, along with many other factors, results in subsequent copulation or rejection.
Elaborate courtship displays can also be seen in many other animal species. For example, the male peacock spider, Maratus volans, uses vibratory signals concurrently with visual displays to court females. The adult male Eastern fence lizard, Sceloporus undulatus, possesses blue and black ventral patches that serve the purpose of sex recognition and intrasexual social signaling. Males will show off these patches to females in an attempt to convince her to copulate.
In many cases, male courtship displays will cause forms of contest competition to develop. This is often seen within lek mating systems. For example, males will seek to obtain a certain spot or position to perform their courtship display. The best spots are regions of high contention as many males want them for themselves. Because of this direct conflict, agonistic encounters between males are fairly common.
Sex-role reversal with courtship displays is far less common in the animal kingdom. In this situation, males are the ones driving sexual selection and putting pressure on the females to attract a mate for copulation. Females experiencing the selective pressure of males will be the ones who develop and possess sexually dimorphic traits. This may include ornamentation, coloration, or development of specific behaviors. This effect can be seen with Long-Tailed Dance Flies, Rhamphomyia longicauda, displaying inflatable abdominal sacs and pinnate tibial scales that are female-specific. Generally, females must invest more energy into the development of gametes and reproduction compared to males. Because of this, this sex-role reversal is a rare phenomenon. Not only must females invest energy into the production of more costly gametes, but they must also put energy towards the development of sexually dimorphic characteristics or performances.
Often, males and females will perform synchronized or responsive courtship displays in a mutual fashion. With many socially monogamous species such as birds, this duet facilitates pre-copulatory reassurance of pair bonding and strengthens post-copulatory dedication to the development of offspring (e.g. Great Crested Grebe, Podiceps cristatus). For example, male and female Crested Auklets, Aethia cristatella, will cackle at one another as a vocal form of mutual display which serves to strengthen a bond between the two. In some cases, males may pair up to perform mutual, cooperative displays in order to increase courtship success and attract females. This phenomenon can be seen with Long-tailed Manakins, Chiroxiphia linearis.
- Males: their interest is to mate with a large number of completely faithful females, thus spreading their genes widely throughout a population.
- Females: their interest is to mate with a large number of fit males, thus producing a large quantity of fit and varied offspring.
This has many consequences. Courtship displays allow the mate performing the selection to have a means by which they can base their copulatory decision. If a female chooses more than one male, then sperm competition comes into play. This is competition between sperm to fertilize an egg, which is very competitive as only a single sperm will achieve union. In some insects, the male injects a cocktail of chemicals in seminal fluid together with sperm. The chemicals kill off older sperm from any previous mates, up-regulates the females' egg-laying rate and reduces her desire to re-mate with another male. The cocktail also shortens the females' lifespan, also reducing her likelihood of mating with other males. Also, some females can get rid of the previous male's sperm.
After mating has taken place, males perform various actions to prevent females from mating again. What action is performed depends on the animal. In some species, the male plugs the female copulatory duct after insemination. In some hymenoptera, the male provides a huge quantity of sperm, enough to last the females' entire life. In some birds and mammals, the male may participate in agonistic behaviors with other candidate males.
Within a Fisherian runaway model, males with certain exaggerated, sexually dimorphic traits may be more fit than those who do not possess them. This means that a gene or set of genes will be favored by female choice over time. This would explain why and how such elaborate traits develop within certain species. However, as time goes on and generations pass, the survival advantage associated with one trait may dissipate due to extreme exaggeration to the point that it decreases fitness.
Based upon the good genes hypothesis, certain exaggerated traits may be supported by other factors that allow for extreme development. For example, the costs associated with bright, and complex plumage can be high. Only males with good genes are able to support a large investment into the development of these traits, which in turn, displays their high fitness.
Both of these hypotheses have valuable input when associated with courtship displays. The development of certain behaviors and sexually dimorphic traits is a central characteristic of this phenomenon. Because both serve to explain the development of elaborate traits it is best to view the two as interacting mechanisms that serve to reinforce one another. Many courtship behaviors are also genetically linked. Individuals that possess genes associated with successful courtship displays will pass this genetic information down from generation to generation. Continued development of these characteristics over time may have led to the unique and brilliant courtship displays we see today.
- Girard, Madeline B., Kasumovic, Michael M., Elias, Damian O. 2011. Multi-modal courtship in the peacock spider, Maratus volans (O.P.-Cambridge, 1874). PloS One vol. 6 (9) p. e25390
- Riede, Tobias, Forstmeier, Wolfgang, Kempenaers, Bart, Goller, Franz. 2015. The functional morphology of male courtship displays in the Pectoral Sandpiper (Calidris melanotos). The Auk vol. 132 (1) pp. 65–77
- Koch, Rebecca E., Krakauer, Alan H., Patricelli, Gail L. 2015. Investigating female mate choice for mechanical sounds in the male Greater Sage-Grouse. Auk vol. 132 (2) p. 349–358
- Beauchamp, A. J. 2014. Calling and display by peacocks (pavo cristatus) at mansion house historic reserve, kawau island, New Zealand. Notornis vol. 61 (1) pp. 27–34
- Martin, A. R., Da Silva, V. M F, Rothery, P. 2008. Object carrying as socio-sexual display in an aquatic mammal. Biology Letters vol. 4 (3) p. 243-245
- Lim, Matthew L. M., Li, Daiqin. 2004. Courtship and male-male agonistic behaviour of Cosmophasis umbratica Simon, an ornate jumping spider (Araneae: Salticidae) from Singapore. Raffles Bulletin of Zoology vol. 52 (2) pp. 435–448
- Wagner, E., Jr., William. 2011. Direct Benefits and the Evolution of Female Mating Preferences: Conceptual Problems, Potential Solutions, and a Field Cricket. Advances in the study of behavior vol 43 p. 273
- Wilts, Bodo D., Michielsen, Kristel, De Raedt, Hans, Stavenga, Doekele G. 2014. Sparkling feather reflections of a bird-of-paradise explained by finite-difference time-domain modeling. Proceedings of the National Academy of Sciences of the United States of America vol. 111 (12) pp. 4363–4368
- Elias, D.O., Girard, M.B., Kasumovic, M.M. 2011. Multi-modal courtship in the peacock spider, Maratus volans (O.P.-Cambridges, 1874), PLoS ONE vol 6 (9) pp. 1–10
- Cox, M. Robert, Henry, B., John-Alder, I., Stephanie, Angela Leo, Skelly. 2005. Testosterone Regulates Sexually Dimorphic coloration in the Eastern Fence Lizard, Sceloporus undulatus. The American Society of Ichthyologists and Herpetologists vol. 3 p597-608.
- Kroiss, Johannes, Lechner, Klaus, Strohm, Erhard. 2009. Male territoriality and mating system in the European beewolf Philanthus triangulum F. (Hymenoptera: Crabronidae): evidence for a “hotspot” lek polygyny. Journal of Ethology vol. 28 (2) pp. 295–304
- Wheeler, J., Gwynne, D.T., Bussière, L.F. 2012. Stabilizing sexual selection for female ornaments in a dance fly. Journal of evolutionary biology vol. 25 (7) pp. 1233–42
- Trivers, L., Robert. 1972. Parental Investment and Sexual Selection. Sexual Selection and the Descent of Man 1871-1971 pp. 136–207
- Servedio, Maria R., Price, Trevor D., Lande, Russell. 2013. Evolution of displays within the pair bond. Proceedings. Biological sciences / The Royal Society vol. 280 (1757) p. 20123020
- Zubakin, V.A., Volodin, I.A., Klenova, A.V., Zubakina, E. V., Volodina, E.V., et al. 2010. Behavior of crested auklets (Aethia cristatella, Charadriiformes, Alcidae) in the breeding season: Visual and acoustic displays. Biology Bulletin vol. 37 (8) pp. 823–835
- Lukianchuk, K.C., Doucet, S.M. 2014. Cooperative courtship display in Long-tailed Manakins Chiroxiphia linearis: predictors of courtship success revealed through full characterization of display. Journal of Ornithology vol. 155 (3) pp. 729–743
- Arnqvist, G. & Rowe, L. 2005. Sexual conflict. Princeton, New Jersey. Princeton University Press.
- Parker, Geoffrey A. 1970. Sperm competition and its evolutionary consequences in insects. Biological Reviews vol. 55 pp. 525–567.
- Schilthuizen, Menno. 2001. Frogs, flies and dandelions: the making of species. Oxford University Press p92 ISBN 019850392X
- Eberhard, W.G. 1996. Female centrol: sexual selection by cryptic female choice. Princeton, New Jersey. Princeton University Press.
- Arnqvist, G. & Rowe, L. 2005. Sexual conflict. Princeton, New Jersey. Princeton University Press.
- Schilthuizen, Menno. 2001. Frogs, flies and dandelions: the making of species. Oxford University Press p. 92 ISBN 019850392X
- Crudgington, H. & Siva-Jothy, M.T. 200. Genital damage, kicking and early death. Nature vol 407 pp. 855–856.
- Chandler, H., Christopher, Ofria, Charles, Dworkin, Ian. 2013. Evolution, international journal of organic evolution vol 67 (1) pp. 110–119
- Dai, Hongzheng, Chen, Ying, Chen, Sidi, Mao, Qiyan, Kennedy, David et al. 2008. Proceedings of the National Academy of Sciences of the United States of America vol 105 (21) pp. 7478–83.