Here are some examples of obligate species and their specific requirements:
* Obligate parasites: These are parasites that absolutely require a host organism to survive and reproduce. They cannot exist independently. Examples include tapeworms, lice, and some viruses.
* Obligate aerobes: These are organisms that require oxygen to survive. They cannot grow or reproduce in the absence of oxygen. Examples include most animals and many bacteria.
* Obligate anaerobes: These are organisms that are killed by the presence of oxygen and can only survive and reproduce in environments without oxygen. Examples include some bacteria found in deep sea vents or in the digestive tracts of animals.
* Obligate mutualists: These are species that completely depend on a relationship with another species for survival. Neither species can survive without the other. Examples include lichen (a symbiotic relationship between a fungus and an alga) or cleaner fish (which clean parasites off larger fish).
The term "obligate" emphasizes the strict dependency of the species on a specific factor. It implies that the species cannot adapt or change its requirements, making it vulnerable if that specific factor is not available.