Final answer:
When species compete, they are primarily doing so for survival and reproduction, as they strive for limited resources that are necessary for their existence. This competition drives evolution and natural selection, influencing both immediate survival and long-term adaptation of the species involved.
Step-by-step explanation:
When species compete, they are primarily competing to accomplish the goals of survival and reproduction (population growth). The competition for limited resources is a fundamental aspect of the natural world and is a driving force behind evolution and natural selection. A variation of traits among individuals in a species (A) can give some organisms advantages in the competition for resources, which can affect their survival and reproductive success. When more offspring are produced than can survive (C), competition intensifies, leading to a situation where only the most well-adapted individuals are able to survive and reproduce. For instance, if two species occupy the same niche and compete for the same food and nesting space, one of two scenarios might occur: the competition could lead to one species adapting and surviving while the other does not (D), or it could lead to the two species developing different specializations, known as character displacement. Yet, it is also possible for one species to gain an advantage through a favorable variation, resulting in increased evolutionary pressure on the competing species to also develop an advantage (B). In a scenario where a sexually reproducing species and an asexually reproducing species are competing for the same resources, the sexually reproducing species may have a greater ability to adapt and evolve due to increased genetic variation, despite the higher energy cost of reproduction (A).
Similarly, when a species encounters rapid environmental change, the ability to reproduce sexually may confer an advantage that allows that species to outcompete a species that only reproduces asexually (D). In summary, competition influences not only the immediate survival of the competing organisms but also the long-term evolutionary trajectories of the species involved. This dynamic process is an essential component of the ecosystems in which these species exist.