● When `color{violet}("Darwin")` spoke of the struggle for existence and `color{violet}("survival")` of the fittest in nature, he was convinced that `color{violet}("interspecific competition")` is a potent force in `color{violet}("organic evolution")`.
● It is generally believed that competition occurs when closely related species compete for the `color{violet}("same resources ")` that are limiting, but this is not entirely true.
● Firstly, totally unrelated species could also compete for the `color{violet}("same resource.")`
● For instance, in some shallow South American lakes visiting `color{brown}("flamingoes ")` and resident `color{brown}(" fishes")` compete for their common `color{violet}("food,")` the `color{violet}("zooplankton")` in the `color{violet}("lake")`.
● `color{violet}("Secondly, resources")` need not be limiting for competition to occur; in `color{violet}("interference competition")`, the `color{violet}("feeding efficiency")` of one species might be reduced due to the `color{violet}("interfering")` and `color{violet}("inhibitory presence")` of the other species, even if resources (`color{violet}("food and space")`) are abundant.
● Therefore, `color{violet}("competition")` is best defined as a process in which the `color{violet}("fitness")` of one species (measured in terms of its `color{violet}("‘r’")` the `color{brown}("intrinsic rate of increase")` ) is significantly lower in the presence of another species.
● It is relatively easy to demonstrate in `color{violet}("laboratory experiments")`, as `color{violet}("Gause")` and other `color{violet}("experimental ecologists")` did, when resources are limited the competitively superior species will `color{violet}("eventually eliminate")` the other species, but evidence for such competitive exclusion occurring in nature is not always conclusive.
● Strong and `color{violet}("persuasive circumstantial evidence")` does exist however in some cases.
● The `color{brown}("Abingdon tortoise ")` in `color{violet}("Galapagos Islands")` became extinct within a `color{violet}("decade")` after goats were introduced on the island, apparently due to the greater `color{violet}("browsing efficiency")` of the goats.
● Another evidence for the `color{violet}("occurrence of competition")` in nature comes from what is called `color{brown}("competitive release")`.
● A species whose `color{violet}("distribution is restricted")` to a small `color{violet}("geographical area")` because of the presence of a `color{violet}("competitively superior")` species, is found to expand its `color{violet}("distributional range")` dramatically when the competing species is experimentally removed.
● When `color{violet}("Darwin")` spoke of the struggle for existence and `color{violet}("survival")` of the fittest in nature, he was convinced that `color{violet}("interspecific competition")` is a potent force in `color{violet}("organic evolution")`.
● It is generally believed that competition occurs when closely related species compete for the `color{violet}("same resources ")` that are limiting, but this is not entirely true.
● Firstly, totally unrelated species could also compete for the `color{violet}("same resource.")`
● For instance, in some shallow South American lakes visiting `color{brown}("flamingoes ")` and resident `color{brown}(" fishes")` compete for their common `color{violet}("food,")` the `color{violet}("zooplankton")` in the `color{violet}("lake")`.
● `color{violet}("Secondly, resources")` need not be limiting for competition to occur; in `color{violet}("interference competition")`, the `color{violet}("feeding efficiency")` of one species might be reduced due to the `color{violet}("interfering")` and `color{violet}("inhibitory presence")` of the other species, even if resources (`color{violet}("food and space")`) are abundant.
● Therefore, `color{violet}("competition")` is best defined as a process in which the `color{violet}("fitness")` of one species (measured in terms of its `color{violet}("‘r’")` the `color{brown}("intrinsic rate of increase")` ) is significantly lower in the presence of another species.
● It is relatively easy to demonstrate in `color{violet}("laboratory experiments")`, as `color{violet}("Gause")` and other `color{violet}("experimental ecologists")` did, when resources are limited the competitively superior species will `color{violet}("eventually eliminate")` the other species, but evidence for such competitive exclusion occurring in nature is not always conclusive.
● Strong and `color{violet}("persuasive circumstantial evidence")` does exist however in some cases.
● The `color{brown}("Abingdon tortoise ")` in `color{violet}("Galapagos Islands")` became extinct within a `color{violet}("decade")` after goats were introduced on the island, apparently due to the greater `color{violet}("browsing efficiency")` of the goats.
● Another evidence for the `color{violet}("occurrence of competition")` in nature comes from what is called `color{brown}("competitive release")`.
● A species whose `color{violet}("distribution is restricted")` to a small `color{violet}("geographical area")` because of the presence of a `color{violet}("competitively superior")` species, is found to expand its `color{violet}("distributional range")` dramatically when the competing species is experimentally removed.