Advertising in biology
Such signalling may be honest, used to attract other organisms, as when flowers use bright colours, patterns, and scent to attract pollinators such as bees; or, again honestly, to warn off other organisms, as when distasteful animals use warning coloration to prevent attacks from potential predators. Such honest advertising benefits both the sender and the receiver.
Other animals may advertise dishonestly; in Batesian mimicry, edible animals more or less accurately mimic distasteful animals to reduce their own risk of being attacked by predators.
Insect-pollinated flowers use bright colours, patterns, rewards of nectar and pollen, and scent to attract pollinators such as bees. Some also use drugs such as caffeine to encourage bees to return more often. Advertising is influenced by sexual selection: in dioecious plants like sallow, the male flowers are brighter yellow (the colour of their pollen) and have more scent than female flowers. Honey bees are more attracted by the brighter male flowers, but not by their scent.
Many flowers that are adapted for pollination by birds produce copious quantities of nectar and advertise this with their red coloration. Insects see red less well than other colours, and the plant needs to devote its energy to attracting birds that can act as pollinators rather than insects that cannot. In fact, the Canary Island endemic Echium wildpretii has two subspecies, a red-flowering one on Teneriffe which is mainly pollinated by birds, and a pink-flowered one on Las Palmas which is pollinated by insects.
Advertising takes a variety of forms in animals. Breeding adults often display to attract a mate. Breeding males of sexually dimorphic birds, such as peacocks, birds of paradise and bower birds, have elaborate plumage, song, and behaviour. These evolved through sexual selection by females. The males use these features alone or in combination to advertise their presence, and, especially but not only in species with lek mating, to compete with rival males. In a lek, the presence of multiple males advertises and potentially benefits all the males present, so they are both collaborating and competing.
Breeding males may also advertise honestly to warn rival males of their strength, a classic example being the red deer, where the roaring of a rutting stag reliably signals its size. The honest advertisement benefits both sender and receiver, as neither need become involved in a costly fight to assess their relative strength. In the breeding season, frogs congregate at suitable breeding sites and call to advertise their presence, particularly at night. Females can distinguish between the fitness of males based on the characteristics of their voices. Desert toads emerge from their underground burrows in response to heavy rain. Males emerge first and when one finds a suitable ephemeral pool, its call attracts others and they all congregate there. Males may call in unison in noisy choruses, and breeding is explosive, a mass of males competing for the smaller number of females.
Colour can be used in advertising. Some butterflies have eyespots on their wings. These make no effort at concealment, but may startle a potential predator into trying elsewhere. The western skink has a distinctive blue tail. If the skink cannot escape from a predator by concealment or flight, it can afford to lose its tail in order to escape with its life. Similarly, some species of grasshopper are well-camouflaged when at rest but flash vivid colouration when flying. The grasshopper thus avoids being eaten while the potential predator hunts in vain for the brightly coloured insect it saw.
Male crickets chirp to attract females, and in some species, their calls can be heard from great distances. However, a certain parasitic fly has taken advantage of this, the female is attracted to a calling male cricket on which it then deposits its developing larvae. Elaborate song is especially well-developed among birds, and again sexual selection has driven its evolution. Songbirds such as warblers have an extensive repertoire of songs, sometimes with thousands of phrases. The sedge warbler assembles an effectively infinite number of songs by assembling phrases in combination. Laboratory experiments by Clive Catchpole demonstrate that female sedge warblers select males with more varied songs, while field observation indicates that such males attract mates before other males.
Breeding females may advertise oestrus (being "on heat" or "in season", i.e. that they are fertile, ovulating and receptive to breeding) with pheromones (scent), courtship behaviour, and visual signals. Human females have long been thought to conceal their ovulation, but women's behaviour changes around the time of ovulation with increased sexual motivation, and they are more attracted to men at that time; conversely, men are more attracted to the scent of women around the time of ovulation than in the non-ovulating (luteal) phase of the menstrual cycle.
Many animals wish to advertise to those of their own species while being camouflaged to avoid predation. Many deep sea fish do this by way of bioluminescence. Patterns of photophores on their undersides emit light that from below hide their silhouettes and resemble the scintillating lights produced by the ever-moving surface layers of water. At the same time, each species has a distinctive pattern of photophores that enables another member of its species to identify it as a con-specific.
- Iolanda, Filella; Primante, Clara; Llusià, Joan; Martín González, Ana M.; Seco, Roger; Farré-Armengol,Gerard; Rodrigo, Anselm; Bosch, Jordi; Peñuelas, Josep (2013). "Floral advertisement scent in a changing plant-pollinators market". Scientific Reports. 3: 3434. doi:10.1038/srep03434. PMC . PMID 24305624.
- "Plants spike nectar with caffeine and give bees a buzz". New Scientist. 15 October 2015. Retrieved 21 March 2016.
- Dötterl, Stefan; Glück, Ulrike; Jürgens, Andreas; Woodring, Joseph; Aas, Gregor (2014). "Floral Reward, Advertisement and Attractiveness to Honey Bees in Dioecious Salix caprea". PLOS ONE. 9 (3): e93421. doi:10.1371/journal.pone.0093421. PMC . PMID 24676333.
- Rodríguez-Gironés, Miguel A.; Santamaría, Luis (2004). "Why are so many bird flowers red?". PLoS Biology. 2 (10): e306. doi:10.1371/journal.pbio.0020350. PMC . PMID 15486585.
- Cott, Hugh B (1940). Adaptive Coloration in Animals. Methuen. page 191
- Slater, Peter J. B. (1999). "8.5 Advertising displays". Essentials of Animal Behaviour. Cambridge University Press. pp. 178–181. ISBN 978-0-521-62996-6.
- Brudzynski, Stefan M. (8 December 2009). Handbook of Mammalian Vocalization: An Integrative Neuroscience Approach. Academic Press. p. 446. ISBN 978-0-08-092337-6.
An advantage of lek mating is that males pool their advertising and courtship signals.
- Clutton-Brock, T. H.; Albon, S. D. (1979). "The Roaring of Red Deer and the Evolution of Honest Advertisement". Behaviour. 69 (3/4): 145–170. doi:10.1163/156853979x00449. JSTOR 4533969.
- Dorcas, Michael E.; Gibbons, Whit (2011). Frogs: The Animal Answer Guide. JHU Press. p. 35. ISBN 978-0-8018-9935-5.
- "Animal behaviour: Truth in advertising". The Economist. 18 June 1998.
- Stebbins, Robert C.; Cohen, Nathan W. (1995). A Natural History of Amphibians. Princeton University Press. p. 159. ISBN 978-0-691-03281-8.
- Stebbins, Robert Cyril; Ipsen, D.C.; Gillfillan, Gretchen (2008). Animal Coloration: Activities on the Evolution of Concealment. NSTA Press. pp. 2–3. ISBN 978-1-933531-29-8.
- Cade, W.H. (1975). "Acoustically orienting parasitoids: Fly phonotaxis to cricket song". Science. 190: 1312–1313. doi:10.1126/science.190.4221.1312.
- Irwin, Mark D.; Stoner, John B.; Cobaugh, Aaron M. (2013). Zookeeping: An Introduction to the Science and Technology. University of Chicago Press. p. 192. ISBN 978-0-226-92532-5.
- Tarin, Juan J.; Gomez-Piquer, Vanessa (2002). "Do women have a hidden heat period?". Human Reproduction. 17 (9): 2243–2248. doi:10.1093/humrep/17.9.2243.
- Bone, Quentin; Moore, Richard (2008). Biology of Fishes. Garland Science. pp. 328, 334. ISBN 978-0-203-88522-2.