Ch. 10 - Principles of Evolution

Principles of Evolution

• Natural Selection: Occurs through four principles: variation, overproduction, adaptation, and descent with modification.
• Variation: Genetic variations are crucial for driving evolutionary changes; without them, no adaptation occurs.
• Overproduction: Species produce more offspring than the environment can support, increasing survival chances for some.
• Adaptation: Organisms with traits suited for their environment have higher reproductive success, allowing them to pass on advantageous traits.
• Descent with Modification: Offspring inherit modified genes from parents, leading to evolution over generations.

Existing Traits in Natural Selection

• Natural selection utilizes existing traits; cannot create new traits. Traits may evolve new functions over time.

Evidence of Evolution

• Fossils: Older fossil layers contain more primitive forms than newer layers, indicating progression over time.
• Geography: Island populations often show variations that resemble the nearest mainland species, suggesting evolutionary adaptation.
• Embryology: Similar embryonic stages reveal common ancestry despite differing adult forms across species.
• Anatomy: Homologous structures share a common evolutionary origin, despite performing different functions in various species.

Genes, Proteins, and Homologous Structures

• Genes dictate protein structure and function, which reflect evolutionary relationships indicated by anatomical and ecological differences.

Common Ancestry

• Similar forelimb structures in humans, bats, and moles signify a shared common ancestor, demonstrating evolutionary ties.

Variation in Species

• Differences like neck length among tortoises illustrate variation within species, fundamental for natural selection.

Resistance to Pesticides

• Insect populations that evolve resistance to pesticides do so because those with survival traits reproduce more successfully after pesticide application.

Surviving Weeds

• Genetic variation among weeds explains why some survive herbicide application despite 99% being killed, showcasing natural selection.

Natural Selection Focus

• Natural selection targets heritable traits within populations, driving evolution through advantageous adaptations.

Light-Colored Lizards Example

• Light-colored lizards thrive in the White Sand region due to their superior camouflage, enhancing their survival and reproductive success.

Catastrophism vs. Gradualism

• Catastrophism: Natural disasters have historically shaped Earth's landscape and led to extinctions.
• Gradualism: Landform changes result from gradual processes occurring over extensive time periods.

Definitions

• Population: Collective individuals of a species within a specific location.
• Variation: Physical differences among individuals within a group.
• Adaptation: Traits that improve an organism's survival and reproduction in its environment.
• Evolution: The long-term biological changes through which species diverge from ancestors.
• Vestigial Structures: Remnants of organs or structures that were functional in ancestral forms but have lost their original use.
• Analogous Structures: Body parts with similar functions across different organisms but differing structures.
• Fossil: The preserved trace of an ancient organism, providing evidence of evolutionary history.
• Paleontology: The field focused on the study of fossils and ancient life forms.