Behavioral Associations


Study of behavioral and social symbioses began as the result of Darwin’s book “The Expressions of the Emotions of Man and Animals,” written 1872. Once recognized that animal behavior could be the result of adaptation to improve survival and reproduction, scientists began to study behavior and social interactions. One challenge faced by scientists studying behavioral symbioses is the difficulty to study relationships over their entire life. While their research focused on behavioral and social symbioses, they also had to consider outside factors such as behavior of other organisms, and environmental factors, “as well as sensory and physiological stimuli” (Paracer, 203). The symbiosis association is important because it can commonly modify the behavior of the different symbionts.




An example of a behavioral symbiotic association is the cleaning of marine fish by specialized fish or shrimp. These fish and shrimp, also called cleaners, regularly remove ectoparasites as well as tissues that are either diseased or damaged. The relationship is important for the marine fish because they are kept free of potentially harmful parasites and disease, while the cleaners also benefit by receiving nutrients from the marine fish. Some of the parasites that are removed by the cleaners include small crustaceans, bacteria mats, and fungi. The nutritional benefit is not great enough to fully sustain the marine species. They also eat small animals from the ocean floor and surrounding water. In addition, the marine fish protect the cleaners from predators. In order for the cleaners to know what part of the marine fish body needs cleaning, they expose the specific part of their body demonstrating a remarkable behavioral pattern, called posing. Host poses include behaviors such as opening mouths and gills in order to allow the cleaner to enter or positioning itself vertically. Although found across the world, such behaviors are mostly found in tropical waters. One risk for the cleaner is that it could be eaten by its host, however “the more highly coevolved the symbiosis between a cleaner and a host, the less likely that the cleaner will be eaten by the host” (Paracer, 205). Many of the cleaners reside in “cleaning stations: often found near the ocean floor near the margins of kelp beds or even in ship wreckage. These stations can be operative for a short or long duration. The hosts are attracted to the cleaning sites as a result of the cleaners displaying bright colors and patterns much different than their surrounding environment as well as performing “dances.” These dances are ritualistic displays done by one of more cleaning fish. Cleaning fish can work alone or in pairs. In addition to marine fish, other species that also use cleaners are turtles, manta rays, and sharks.
cleaning_fish.jpg
http://c.photoshelter.com/img-get/I0000mO4zPQeLaPU/s/600/600/ps30060-D-brandon-cole-cleaner-wrasse-sweetlips-behavior.jpg


Social symbioses exist between individuals and societies as well as between different societies, particularly among insects and birds. For insects, most often the individual plays a small role within the larger society. This lends to increased vulnerability for a different species of insect to disrupt symbiotic interruptions by intruding into the society.

There are over two hundred species of ants that have evolved various types of social parasitism with other ants that range in their degree of integration. “The simplest form of social parasitism is one in which a colony of ants builds a nest next to a colony of a different species and steals food from and preys on the neighboring workers”(Paracer, 209). An even more aggressive behavior occurs when one colony of ants completely occupies the nest of another species. A more highly evolved form of social parasitism occurs when many different species of ants are all found living in the same colony. Although it is unknown why, in some instances a queen ant of one species may actually enter and be accepted by an outside colony. The previous queen is removed either directly by the intruder queen or killed by her own workers. Over time, the offspring of the old queen die out and are replaced by offspring of the new queen. Another type of social parasitism is a form of slavery where “some ant species raid the nests of different ant species, steal pupae, and return them to their own nest” (Paracer, 209). When the young ants develop they act as slaves in the new nest, performing all the work necessary for building, foraging, and rearing the brood. Current research is still being done to determine the origin of parasitic ants.

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http://www.morning-earth.org/graphic-e/SymbiosisAnts.html


A similar social symbiotic association in birds occurs in situations where young maybe missing a strong bond with their parents. When eggs are laid in nests not belonging to their parents, they are taken in as adopted babies by the new parents. “These parents are easily deceived when eggs are laid in their nests by other birds and will incubate the foreign eggs and care for the young along with their own” (Paracer, 208). This is known as egg mimicry. This association rarely occurs among mammals due to the strong recognition bonds that occur between parents and their young early on. This social parasitism is most common among cuckoos and cow birds. Obligate brood parasitism is found in about one hundred species of cuckoos indicating that in order for their eggs to hatch they must depend on other birds. Parent cuckoos find hosts nest to lay their eggs and upon hatching, the young cuckoos “destroy the host eggs and kill any young of the host”(Paracer 210). The young of the cuckoo deceive the host parents based on their similar size and color.
In addition to similar color and size, the eggs also have thick shells to resist breaking when dropped into the host nest.

Another example of behavioral symbiosis includes that of the fig plant and fig wasp. The symbiosis is an obligate mutualism in which the fig benefits from pollination while the wasp received nutritional benefits as well as a safe environment for reproduction. The female fig wasp enters into the fig via the ostiolum and deposits eggs within the flowers of the fig fruit. Just after depositing the eggs, the female dies however the larvae continue to develop and hatch within the fig. The male wasp fertilizes the new female wasps and assists in “chewing” their way out of the flower. The males are unable to adjust to the outside light and die within the fig flower. The females are able to collect pollen within the fig and then exit to find a new host in which to deposit the pollen.

Fig-wasp Symbiosis
Deep mtDNA divergences indicate cryptic species in a fig-pollinating wasp

A Critical Review--Deep mtDNA divergences indicate cryptic species in a fig-pollinating wasp

Fig-wasp Mutualism
Host sanctions and pollinator cheating in the fig tree–fig wasp mutualism






Further Examples of Behavioral Symbioses:

The clown fish and the sea anemone

Whale & Barnacle Symbiosis

Miami Blue Butterfly Larvae and Ants

Oxpecker and Ungulate Symbiosis

Ant, Caterpillar Symbiosis

Common Wrasse Cleaner Fish

Shark's symbiosis with Remora and Pilot fish

Ant-Fungal Symbiosis