In Darwin's concept of the struggle for existence and survival of the fittest in nature, what was he convinced about?

Interspecific competition is a significant force in organic evolution.

When Darwin spoke of the struggle for existence and the survival of the fittest in nature, he was indeed convinced that interspecific competition is a potent force in organic evolution. Interspecific competition refers to the competition for resources between different species occupying the same ecological niche.

While it is generally true that closely related species may compete for the same limited resources, it is important to note that competition is not solely restricted to closely related species. In fact, competition can occur between species that are not closely related but have similar resource requirements.

The availability of resources in an ecosystem is often limited, and different species may have overlapping needs for these resources. For example, multiple species of birds may compete for the same food sources or different herbivorous species may compete for access to the same plants. In such cases, the competition for resources can drive evolutionary changes within the competing species.

Interspecific competition can have several outcomes. It may lead to the displacement of one species by another, the partitioning of resources among coexisting species, or the evolution of specialized adaptations that reduce competition. These adaptations could include changes in behavior, morphology, or ecological niche.

Darwin recognized that interspecific competition played a crucial role in shaping the natural world and driving the process of organic evolution. The competition for limited resources can act as a selective pressure, favoring individuals or species with traits that provide a competitive advantage, ultimately leading to the survival and reproduction of those better adapted to their environment.