Symbiosis

Anya E. Vostinar 1 *, Katherine G. Skocelas 2, Alexander Lalejini 2 and Luis Zaman 3 • 1SymbuLab, Carleton College, Computer Science, Northfield, MN, United States • 2Digital Evolution Lab, Michigan State University, Department of Computer Science, Program in Ecology, Evolution, and Behavior, BEACON Center for the Study of Evolution in Action, East Lansing, MI, United States • 3ZE3 Lab, University of Michigan, Department of Ecology and Evolutionary Biology & Center for the Study of Complex Systems, Ann Arbor, MI, United States Symbiosis, the living together of unlike organisms as symbionts, is ubiquitous in the natural world. Symbioses occur within and across all scales of life, from microbial to macro-faunal systems. Further, the interactions between symbionts are multimodal in both strength and type, can span from parasitic to mutualistic within one partnership, and persist over generations. Studying the ecological and evolutionary dynamics of symbiosis in natural or laboratory systems poses a wide range of challenges, including the long time scales at which symbioses evolve de novo, the limited capacity to experimentally control symbiotic interactions, the weak resolution at which we can quantify interactions, and the idiosyncrasies of current model systems. These issues are especially challenging when seeking to understand the ecological effects and evolutionary pressures on and of a symbiosis, such as how a symbiosis may shift between parasitic and mutualistic modes a...

Symbiosis Symbiosis means "living together". Symbiotic relationships are very common in the ocean, especially among animals living on coral reefs. There are several kinds of symbiosis: "mutualism" is a partnership in which both animals benefit; "parasitism" is a relationship in which one animal benefits at the expense of the other; "commensalism" is a term used to cover all other kinds of symbiosis - usually relationships where one partner benefits, while the other is neither helped nor harmed. Shark with Remora Jellyfish with Fish Eagle Ray with Jack Crabs and Urchin, Indonesia Crab and Jellyfish Crab with Urchin Squat lobsters, Indonesia Parasitic Isopods, Indonesia Anemone with Commensals, Indonesia Shrimp on Sea Cucumber Shrimp on Bubble Coral Shrimp on Fire Urchin Decorator Crab Decorator Crabs Sponge Crab Wire Coral Goby Blind Shrimp and Goby Gobies on Soft Coral Batfish with Cleaners Shrimp on Nudibranch Shrimp on Featherstar Crab on Sea Anemone Crab on Jellyfish Boxer Crab with Anemones Brittlestar on Sponge Anemonefish Crab on Barrel Sponge

\( \newcommand\) • • • • • • • Commensalism Commensalism is a symbiotic relationship in which one species benefits while the other species is not affected. One species typically uses the other for a purpose other than food. For example, mites attach themselves to larger flying insects to get a “free ride.” Hermit crabs use the shells of dead snails for homes. Parasitism Parasitism is a symbiotic relationship in which one species (the parasite) benefits while the other species (the host) is harmed. Many species of animals are parasites, at least during some stage of their life. Most species are also hosts to one or more parasites. Some parasites live on the surface of their host. Others live inside their host. They may enter the host through a break in the skin or in food or Figure Roundworms like this one might eventually fill a dog’s intestine unless it gets medical treatment. Some parasites kill their host, but most do not. It’s easy to see why. If a parasite kills its host, the parasite is also likely to die. Instead, parasites usually cause relatively minor damage to their host. Summary • Symbiosis is a close relationship between two species in which at least one species benefits. • Mutualism is a symbiotic relationship in which both species benefit. • Commensalism is a symbiotic relationship in which one species benefits while the other species is not affected. • Parasitism is a symbiotic relationship in which one species (the parasite) benefits while the other specie...

Contunico © ZDF Enterprises GmbH, Mainz; Thumbnail © Wirestock/Dreamstime.com Close living arrangements between two different species is called symbiosis. The word comes from the Greek word meaning “state of living together.” Usually the two organisms are in close physical contact, with one living on or in the other. In some cases, however, the relationship is less intimate. Symbiosis is classified into: mutualism (once called symbiosis), commensalism, and parasitism. These relationships range from mutually beneficial to harmful, or even fatal, for one of the species. Mutualism © Angel DiBilio/Shutterstock.com In mutualism both partners benefit from the relationship. One of the best-known mutualistic relationships is the one between nitrogen-fixing Rhizobium bacteria and several leguminous plants such as beans, peas, peanuts, and alfalfa. Human beings, animals, and most plants need nitrogen to survive but cannot metabolize it from the air. Rhizobium bacteria, which live in the soil, enter the roots of Mutualistic relationships between animals and plants or microorganisms also exist. Some plants must be pollinated by insects, who obtain food from the plant in the form of pollen or nectar. Many animals, including human beings, have see Commensalism © Fiona Ayerst/Dreamstime.com A relationship in which one member benefits while the other is neither helped nor harmed is known as commensalism. For example, the remora fish can attach itself to a shark, whale, or large turtle and...

Symbiosis is a relationship between two or more organisms that live closely together. There are several types or classes of symbiosis: Commensalism One organism benefits and the other is neither harmed nor helped. Mutualism Both organisms benefit. An obligate mutualist cannot survive without its partner; a facultative mutualist can survive on its own. Parasitism One organism (the parasite) benefits and the other (the host) is harmed. To be successful, a symbiotic relationship requires a great deal of balance. Even parasitism, where one partner is harmed, is balanced so that the host lives long enough to allow the parasite to spread and reproduce. These delicate relationships are the product of long years of co-evolution. Bacteria were the first living things on the planet, and all of Earth's other creatures have been living and evolving with them for hundreds of millions of years. Today, microbes are essential for many organisms' basic functions, including nourishment, reproduction, and protection. Toxoplasma is a parasitic protist that can infect a range of animals, including mice, rats, and people. But to reproduce sexually, it must infect a cat. In an amazing and complex relationship, the parasite enters the brain of infected rodents, where it changes the host's behavior, making it more likely to be caught and eaten by a cat! Mice infected with toxoplasma lose their fear of cats. They are more active, and more likely to spend time exploring open spaces. In one study, ma...