Natural Selection

Question: What is Evolution?
Definition of Evolution: The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.
- Example of Artificial Selection: Selective breeding of plants and animals whereby desired traits are chosen by the breeder (e.g., breeding dogs for specific characteristics such as size, color, or temperament).

Described as: A natural process that provides a scientific explanation for the diversity of life.
- Key Concept: Descent with Modification
- Explanation: All organisms share a common ancestor from which they have evolved over time, resulting in diverse forms and functions.

Concept: All populations of organisms have the potential to produce many offspring; however, they compete for a limited amount of environmental resources, leading to struggle among individuals.

Key Idea: Differences among individuals in a population known as variations.
- Importance: Individuals with certain advantageous variations are better adapted to their particular environments, enhancing their survival prospects.
- Definition of Adaptation: A heritable characteristic that increases an organism's ability to survive and reproduce in a specific environment.

Principle: Adaptations impact an organism's fitness, defined as:
- Fitness: How well an organism can survive and proliferate in its environment.
- Evolutionary Context: Survival goes beyond mere existence; it is about the number of offspring an organism leaves behind and their ability to reproduce.

Definition: The process by which organisms that are best suited to their environment survive and reproduce more successfully (commonly known as survival of the fittest).
- Conditions for Natural Selection:
- Overproduction: More individuals are born than can survive, leading to competition (the struggle for existence).
- Variation and Adaptation: Heritable variations affect survival and reproductive success.
- Differential Reproductive Success: Fitness varies among individuals, influencing who survives and reproduces.

Importance of Reproduction: Natural Selection relies on an individual’s ability to reproduce and leave behind descendants.
- Key Outcome: Well-adapted individuals are more likely to survive and reproduce, which leads to gradual changes (small adaptations) over long periods.
- Principle of Common Descent: All species, both living and extinct, are interconnected by descent from ancient common ancestors, displaying diversity primarily due to natural selection and adaptation processes.