Many traits are passed from parent to offspring. Some of these traits will help with survival and reproduction, which means the individuals with the favorable traits will have more surviving offspring. Because helpful traits are heritable, these specific trait with be more common in the following generations. 

Heritable Traits

Individuals can produce more offspring than their environment can support, which creates competition and "survival of the fittest". Thus, each generation competes for limited resources. 

Survival Rate of Offspring

Offspring in a generation will not be identical and different traits can vary. These varying traits are also heritable, making different offspring more fit for their environment than others. This also means that a whole generation cannot be favorable, some individuals will survive while others won't. 

Varying Heritable Traits in Offspring

- Heritable Traits
- More offspring are produced than can survive
- offspring vary in heritable traits

University of California, Davis

- While evolution allows for modifications to occur in species over time, only the most advantageous modifications will be passed on to the descendants of a population over time 
- This is known as natural selection, first described by Charles Darwin and Alfred Wallace

Evolution through Natural Selection

Khan Academy. (n.d.). Darwin, evolution, &amp; natural Selection (article). Khan Academy. https://www.khanacademy.org/science/ap-biology/natural-selection/natural-selection-ap/a/darwin-evolution-natural-selection. 

Darwin, evolution, and natural selection

- A specific modification (to a certain trait)  that is most likely to be passed on during the process of natural selection, and will be seen in the majority of the population 

Adaptations 

- A type of natural selection in which one sex may favor certain traits of another sex as they choose someone to reproduce with 

Sexual Selection 

A unique set of environmental opportunities or challenges to which an organism is adapted. Different animals have evolved neural behaviors and mechanisms to allow them to maneuver ecological niches. 

Ecological Niche

Darwin's Key Observations of Natural Selection

Natural selection depends on an environment and what traits are superior within that environment. Traits favorable in one environment may be harmful in another. The environment provides the context of natural selection. 

Natural Selection within an Environment

Charles Darwin was a British naturalist who proposed the theory of evolution through natural selection, defining it as 'descent with modification.' He published his theories in his influential book 'On the Origin of Species.' A well-known painted portrait captures his appearance during the period he developed his theories.

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