coevolution
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What is coevolution in biology?
Coevolution is a biological process where two or more ecologically interdependent species undergo reciprocal evolutionary changes that affect their interaction. The activity of each species involved exerts selection pressure on the others; for example, if faster prey emerge, predators that cannot keep up are selected against.
Coevolution is a primary method by which biological communities are organized and can result in specialized relationships between species, such as those of predator and prey, pollinator and plant, and parasite and host. Coevolution can either enhance or lessen antagonism between species, and it doesn't necessarily require the presence of antagonism. Human activities can disrupt coevolution, with consequences that are hard to predict.
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How is coevolution different from regular evolution?
Coevolution is a type of evolution where two or more species reciprocally influence each other's evolutionary trajectory. This contrasts with regular evolution, where a species adapts primarily to its environment, not specifically to another species. Coevolution often occurs between interacting species, such as predator and prey, host and parasite, or plant and pollinator. The adaptation of one species can create a selection pressure on the other, leading to an "evolutionary arms race" or other specialized relationships. Human activities can disrupt coevolution, affecting community organization and potentially causing extinctions.
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What are some examples of coevolution between two species?
Coevolution is when two or more species reciprocally influence each other's evolution through natural selection. This process is crucial in shaping the structure of biological communities and can result in specialized relationships.
Examples of coevolution:
* Predator-prey relationships The emergence of faster prey can drive the selection of faster predators, leading to an evolutionary "arms race".
* Parasite-host interactions Host density and parasite transmission rates can influence the evolution of virulence in parasites. For example, the evolution of myxoma virus in rabbits in Australia shows how quickly coevolution of parasites and hosts can proceed to a new outcome.
* Mutualistic interactions In pollination, plants may evolve specific floral shapes to attract certain pollinators, while pollinators develop specialized structures or behaviors to access nectar and pollen.
* Mimicry Species may evolve to resemble each other for protection, as seen in Müllerian mimicry where distasteful species share similar appearances, or in Batesian mimicry where a harmless species mimics a harmful one.2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How do predators and prey influence each other's evolution through coevolution?
Predator and prey species engage in coevolution, where they act as selective pressures on each other, leading to reciprocal evolutionary changes. For instance, if prey develops speed to evade predators, predators may evolve counter-adaptations to maintain their hunting efficiency.
This dynamic can escalate into an evolutionary arms race, where each species continually develops better offensive or defensive mechanisms. Examples include thicker shells in marine mollusks and stronger claws in their crab predators, demonstrating how species adapt to each other over time.
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How do plants and pollinators show signs of coevolution?
Coevolution is a reciprocal evolutionary change between interacting species, where each species' traits act as a selection pressure on the others. Plants and pollinators show coevolution through specialized relationships and mutual dependence.
Some examples:
* Floral traits and pollinator behavior Flower colors and nectar guides evolved to attract pollinators, while insects developed specialized mouthparts to feed on nectar.
* Yucca and Yucca moth Yuccas depend solely on yucca moths for pollination, and moths rely on yucca seeds for offspring development. The female moth collects pollen and places it on the flower's stigma, ensuring seed development for her larvae.
* Orchids and bees Bee orchids mimic the appearance, scent, and texture of female bees to lure male bees into "pseudocopulation." During this process, the flower attaches pollen to the bee, which then pollinates another flower.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Why is coevolution important for biodiversity and the balance of ecosystems?
Coevolution is a key process for structuring biological communities, involving reciprocal evolutionary changes among interacting species. This interaction exerts selective pressure, leading to specialized relationships, such as those between predators and prey or pollinators and plants. Coevolution maintains community organization by ensuring checks and balances, as seen in the coevolution of the myxoma virus and rabbit species. Disruptions to coevolution, often caused by human activities like habitat fragmentation or the introduction of new species, can negatively affect the organization of communities and alter natural selection, with often unpredictable consequences for the biosphere.
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coevolution, the process of reciprocal evolutionary change that occurs between pairs of species or among groups of species as they interact with one another. The activity of each species that participates in the interaction applies selection pressure on the others. In a predator-prey interaction, for example, the emergence of faster prey may select against individuals in the predatory species who are unable to keep pace. Thus, only fast individuals or those with adaptations allowing them to capture prey using other means will pass their genes to the next generation. Coevolution is one of the primary methods by which biological communities are organized. It can lead to very specialized relationships between species, such as those between pollinator and plant, between predator and prey, and between parasite and host. It may also foster the evolution of new species in cases where individual populations of interacting species separate themselves from their greater metapopulations for long periods of time.
How an interaction coevolves between species depends not only on the current genetic makeup of the species involved but also on new mutations that arise, the population characteristics of each species, and the community context in which the interaction takes place. Under some ecological conditions (such as in some predator-prey interactions or between competitors for a resource), an antagonistic interaction between two species can coevolve to enhance the antagonism; the species “build up” methods of defense and attack, much like an evolutionary arms race. Under other ecological conditions (such as in certain parasite-host interactions), however, the antagonism may be lessened.
Coevolution does not necessarily require the presence of antagonism. The interactions or characteristics within groups of unrelated species may converge to allow individual species to exploit valuable resources or enjoy increased protection. Once an interaction evolves between two species, other species within the community may develop traits akin to those integral to the interaction, whereby new species enter into the interaction. This type of convergence of species has occurred commonly in the evolution of mutualistic interactions, including those between pollinators (such as bees) and plants and those between vertebrates (such as birds and bats) and fruits.
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Some of the species drawn into mutualistic interactions become co-mutualists, contributing as well as benefiting from the relationship, whereas others become cheaters that only exploit the relationship. In many interactions between bee pollinators and plants, bees collect the nectar from the reproductive parts of the plant and are often dusted with pollen in the process. When the bees fly to another plant of the same species, they may fertilize the plant by depositing pollen on the plant’s stigma. In contrast, some bumblebees, such as those of Bombus terrestris, obtain nectar from the plant without picking up or dropping off pollen. They cheat by cutting through other parts of the plant instead of entering the flower.
In other cases, the behaviour or appearance of several species may converge to enhance their mutual protection (see Müllerian mimicry). For example, several species of heliconid butterflies that are distasteful to predators have evolved to resemble one another. In addition, one species may evolve to mimic the behaviour or appearance of another to garner some of the same protections enjoyed by the model species (see Batesian mimicry). This evolutionary strategy has been successful for nonvenomous snakes, such as the scarlet king snake (Lampropeltis elapsoides), whose coloration closely resembles that of coral snakes, which can deliver a poisonous bite.
Coevolution is a complex process that occurs on many levels. It may appear in situations where one species interacts closely with several others, such as the interaction between European cuckoos (Cuculus canorus) and the other species whose nests they parasitize; it may involve many species, as in relationships between fruit-bearing plants and birds; or it may take place in some subgroups of species but not others (see geographic mosaic theory of coevolution). It is important to note that human activities often disrupt the process of coevolution by changing the nature and the extent of the interactions between coevolving species. Some examples of harmful human activities include habitat fragmentation, increased hunting pressure, favouritism of one species over another, and the introduction of exotic species into ecosystems that are ill-equipped to handle them (see also community ecology).