Aquatic ecology and Biodiversity

Unit 8- Animal associations and interactions

8.12. Natural selection
Natural selection is the nonrandom process by which biologic traits become more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution. Charles Darwin coined the term "natural selection," Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift. Natural selection is a very efficient, predictable mechanism of evolution, illustrating mainly on
• how species adapt to their environment
• the reproductive success of a species
• design in nature
• evidence of evolution in action, e.g., antibiotic resistance etc.
What is natural selection
Natural selection is how species evolve by adapting to their environment and it is the driving force behind the evolutionary process. It explains design in nature. Fishing drives natural selection for smaller fish that grow more slowly and have reduced reproductive potential. Most fisheries are collapsing and many are on the brink of potentially irreversible loss. There are massive evolutionary shifts going on in the populations of fish. Large fish with huge reproductive potential are being replaced by smaller fish with diminished reproductive potential.

Natural selection is the process by which species adapt to their environment. Here, the organisms with the best or most favorable genetic adaptations out-compete other organisms in a population, tending to displace the less-adapted organisms. Natural selection leads to evolutionary change when individuals with certain characteristics have a greater survival or reproductive rate than other individuals in a population and pass on these inheritable genetic characteristics to their offspring. Simply, natural selection is a consistent difference in survival and reproduction between different genotypes, or even different genes, in what we could call reproductive success. (a genotype is a group of organisms sharing a specific genetic makeup.)
Darwin used this concept of natural selection to explain the variation he observed within and between species. It became clear that those adaptations which conferred survival advantages in a given environment would come to dominate a population, or else being equal.