Ageneralist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of differentresources (for example, aheterotroph with a varieddiet). Aspecialist species can thrive only in a narrow range of environmental conditions or has a limited diet. Mostorganisms 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.
Omnivores are usually generalists.Herbivores 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 monophagouskoala, which subsists almost entirely oneucalyptus leaves. Theraccoon is a generalist, because it has a natural range that includes most of North and Central America, and it is omnivorous, eatingberries, insects such as butterflies, eggs, and various small animals.
When it comes to insects, particularly native bees andlepidoptera (butterflies and moths), many are specialist species.[1][2] It is estimated that about half of native US bee species are pollen specialists, meaning they collect resources from specificgenera.[3] For instance, the threatenedmonarch butterfly exclusively lays its eggs onmilkweed species. This reliance underscores the critical role ofnative plants in supporting ecological food chains.
The distinction between generalists and specialists is not limited to animals. For example, some plants require a narrow range of temperatures, soil conditions andprecipitation to survive while others can tolerate a broader range of conditions. Acactus could be considered a specialist species. It will die during winters at highlatitudes or if it receives too much water.
Whenbody weight is controlled for, specialist feeders such asinsectivores andfrugivores have largerhome ranges than generalists like somefolivores (leaf-eaters), whose food-source is less abundant; they need a bigger area forforaging.[4] An example comes from the research ofTim Clutton-Brock, who found that theblack-and-white colobus, a folivore generalist, needs a home range of only 15ha. On the other hand, the more specializedred colobus monkey has a home range of 70 ha, which it requires to find patchy shoots, flowers and fruit.[5]
When environmental conditions change, generalists are able to adapt, but specialists tend to fall victim toextinction much more easily.[6] For example, if a species of fish were to go extinct, any specialistparasites wouldalso face extinction. On the other hand, a species with a highly specializedecological niche is more effective atcompeting with other organisms.[citation needed] For example, a fish and its parasites are in anevolutionary arms race, a form ofcoevolution, 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 thespeciation of more specialized species provided conditions remain relatively stable. This involvesniche partitioning as new species are formed, andbiodiversity 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.[7] 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.[8]
https://www.webpages.uidaho.edu/range556/appl_behave/projects/different_strokes.html
