Coevolution refers to evolution that occurs among interdependent species as a result of specific interactions. That is, adaptations occurring in one species spur reciprocal adaptations in another species or multiple species. Coevolutionary processes are important in ecosystems as these types of interactions shape relationships among organisms at various trophic levels in communities.
- Coevolution involves reciprocal adaptive changes that occur among interdependent species.
- Antagonistic relationships, mutualistic relationships, and commensalistic relationships in communities promote coevolution.
- Coevolutionary antagonistic interactions are observed in predator-prey and host-parasite relationships.
- Coevolutionary mutualistic interactions involve the development of mutually beneficial relationships between species.
- Coevolutionary commensalistic interactions include relationships where one species benefits while the other is not harmed. Batesian mimicry is one such example.
While Darwin described coevolution processes in plant-pollinator relationships in 1859, Paul Ehrlich and Peter Raven are credited as the first to introduce the term "coevolution" in their 1964 paper Butterflies and Plants: A Study in Coevolution. In this study, Ehrlich and Raven proposed that plants produce noxious chemicals to prevent insects from eating their leaves, while certain butterfly species developed adaptations that allowed them to neutralize the toxins and feed on the plants. In this relationship, an evolutionary arms race was occurring in which each species was applying selective evolutionary pressure on the other that influenced adaptations in both species.
Interactions among biological organisms in ecosystems or biomes determine the types of communities in specific habitats. The food chains and food webs that develop in a community help to drive coevolution among species. As species compete for resources in an environment, they experience natural selection and the pressure to adapt to survive.
Several types of symbiotic relationships in communities promote coevolution in ecosystems. These relationships include antagonistic relationships, mutualistic relationships, and commensalistic relationships. In antagonistic relationships, organisms compete for survival in an environment. Examples include predator-prey relationships and parasite-host relationships. In mutualistic coevolutionary interactions, both species develop adaptations for the benefit of both organisms. In commensalistic interactions, one species benefits from the relationship while the other is not harmed.
Antagonist InteractionsFemale leopard stalking prey in tall grass. Eastcott Momatiuk/The Image Bank/Getty Images Plus
Coevolutionary antagonistic interactions are observed in predator-prey and host-parasite relationships. In predator-prey relationships, prey develop adaptations to avoid predators and predators acquire additional adaptations in turn. For example, predators that ambush their prey have color adaptations that help them to blend into their environment. They also have heightened senses of smell and vision to accurately locate their prey. Prey that evolve to develop heightened visual senses or the ability to detect small changes in air flow are more likely to spot predators and avoid their ambush attempt. Both predator and prey must continue to adapt to improve their chances for survival.
In host-parasite coevolutionary relationships, a parasite develops adaptations to overcome a host's defenses. In turn, the host develops new defenses to overcome the parasite. An example of this type of relationship is evidenced in the relationship between Australian rabbit populations and the myxoma virus. This virus was used in an attempt to control the rabbit population in Australia in the 1950s. Initially, the virus was highly effective in destroying rabbits. Over time, the wild rabbit population experienced genetic changes and developed resistance to the virus. The lethality of the virus changed from high, to low, to intermediate. These changes are thought to reflect the coevolutionary changes between the virus and rabbit population.
Mutualistic InteractionsThe coevolution between fig wasps and figs has become so profound that neither organism can exist without the other. Encyclopaedia Britannica/UIG/Getty Images Plus
Coevolutionary mutualistic interactions that occur between species involve the development of mutually beneficial relationships. These relationships may be exclusive or general in nature. The relationship between plants and animal pollinators is an example of a general mutualistic relationship. The animals depend on the plants for food and the plants depend on the animals for pollination or seed dispersal.
The relationship between the fig wasp and the fig tree is an example of an exclusive coevolutionary mutualistic relationship. Female wasps of the family Agaonidae lay their eggs in some of the flowers of specific fig trees. These wasps disperse pollen as they travel from flower to flower. Each species of fig tree is usually pollinated by a single wasp species that only reproduces and feeds from a specific species of fig tree. The wasp-fig relationship is so intertwined that each depends exclusively on the other for survival.
MimicryMocker Swallowtail. AYImages/iStock/Getty Images Plus
Coevolutionary commensalistic interactions include relationships where one species benefits while the other is not harmed. An example of this type of relationship is Batesian mimicry. In Batesian mimicry, one species mimics the characteristic of another species for protective purposes. The species that is being mimicked is poisonous or harmful to potential predators and thus mimicking its characteristics provides protection for the otherwise harmless species. For example, scarlet snakes and milk snakes have evolved to have similar coloration and banding as venomous coral snakes. Additionally, mocker swallowtail (Papilio dardanus) species of butterfly mimic the appearance of butterfly species from the Nymphalidae family that eat plants containing noxious chemicals. These chemicals make the butterflies undesirable for predators. Mimicry of Nymphalidae butterflies protects Papilio dardanus species from predators that can not differentiate between the species.
- Ehrlich, Paul R., and Peter H. Raven. "Butterflies And Plants: A Study In Coevolution." Evolution, vol. 18, no. 4, 1964, pp. 586-608., doi:10.1111/j.1558-5646.1964.tb01674.x.
- Penn, Dustin J. "Coevolution: Host-Parasite." ResearchGate, www.researchgate.net/publication/230292430_Coevolution_Host-Parasite.
- Schmitz, Oswald. "Predator and Prey Functional Traits: Understanding the Adaptive Machinery Driving Predator-prey Interactions." F1000Research vol. 6 1767. 27 Sep. 2017, doi:10.12688/f1000research.11813.1
- Zaman, Luis, et al. "Coevolution Drives the Emergence of Complex Traits and Promotes Evolvability." PLOS Biology, Public Library of Science, journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002023.