What did Darwin mean by the struggle for existence? Give examples of various forms of struggle for existence.

Darwin identified three forms of the struggle for existence: intraspecific, interspecific, and the struggle with adverse environmental factors. Darwin’s struggle for existence is a process of interaction between organisms and the environment.
Intraspecific struggle – occurs between individuals of the same species. It proceeds most acutely, as individuals have the same capabilities and needs, I use similar resources for life. For example, lions find out relationships in the struggle for territory, cheetahs fight for possession of prey, or a male of the same species fights for a female.
Interspecific struggle – occurs between individuals of different species in the process of relations “predator-prey” (fox-mouse), “parasite-host” (mosquito-mammal), “plants-herbivore” (clover-hoofed), competition (wolf-bear wolf fox). Predators compete for prey (prey), plants compete for light, moisture, and soil minerals.
Fighting adverse conditions – occur when organisms are exposed to extreme abiotic factors – heat or cold, dryness or humidity. Example, in the 40s. in Russia, the death of moles was observed. In conditions of prolonged cold weather, only the smallest animals survived, and relatively large animals died, because they could not find enough food for themselves. In other words, small moles were better adapted to tolerate cold weather.

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