A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet). A specialist species can thrive only in a narrow range of environmental conditions or has a limited diet. Most organisms do not all fit neatly into either group, however. Some species are highly specialized (the most extreme case being monophagous, eating one specific type of food), others less so, and some can tolerate many different environments. In other words, there is a continuum from highly specialized to broadly generalist species.

Description

Omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...

s are usually generalists.

Herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

s are often specialists, but those that eat a variety of plants may be considered generalists. A well-known example of a specialist animal is the monophagous koala, which subsists almost entirely on eucalyptus leaves. The raccoon is a generalist, because it has a natural range that includes most of North and Central America, and it is omnivorous, eating berries, insects such as butterflies, eggs, and various small animals. The distinction between generalists and specialists is not limited to animals. For example, some plants require a narrow range of temperatures, soil conditions and precipitation to survive while others can tolerate a broader range of conditions. A cactus could be considered a specialist species. It will die during winters at high latitudes or if it receives too much water. When

body weight Human body weight is a person's mass or weight. Strictly speaking, body weight is the measurement of weight without items located on the person. Practically though, body weight may be measured with clothes on, but without shoes or heavy accessor ...

is controlled for, specialist feeders such as

insectivore A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores wer ...

s and

frugivore A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance an ...

s have larger home ranges than generalists like some folivores (leaf-eaters), whose food-source is less abundant; they need a bigger area for foraging. An example comes from the research of Tim Clutton-Brock, who found that the

black-and-white colobus Black-and-white colobuses (or colobi) are Old World monkeys of the genus ''Colobus'', native to Africa. They are closely related to the red colobus monkeys of genus '' Piliocolobus''. There are five species of this monkey, and at least eight subs ...

, a folivore generalist, needs a home range of only 15 ha. On the other hand, the more specialized red colobus monkey has a home range of 70 ha, which it requires to find patchy shoots, flowers and fruit. When environmental conditions change, generalists are able to adapt, but specialists tend to fall victim to extinction much more easily. For example, if a species of fish were to go extinct, any specialist parasites would also face extinction. On the other hand, a species with a highly specialized ecological niche is more effective at

competing Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

with other organisms. For example, a fish and its parasites are in an evolutionary arms race, a form of co-evolution, in which the fish constantly develops defenses against the parasite, while the parasite in turn evolves adaptations to cope with the specific defenses of its host. This tends to drive the

speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

of more specialized species provided conditions remain relatively stable. This involves niche partitioning as new species are formed, and biodiversity is increased. A benefit of a specialist species is that because the species has a more clearly defined niche, this reduces competition from other species. On the other hand, generalist species, by their nature, cannot realize as much resources from one niche, but instead find resources from many. Because other species can also be generalists, there is more competition between species, reducing the amount of resources for all generalists in an ecosystem. Specialist herbivores can have morphological differences as compared to generalists that allow them to be more efficient at hunting a certain prey item, or able to eat a plant that generalists would be less tolerant of.

Summary

References

https://www.webpages.uidaho.edu/range556/appl_behave/projects/different_strokes.html{{modelling ecosystems Ecology

Description

Summary

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References