Darwin’s Theory of Evolution

The History of Evolution Evolution is defined as change over timeEvolution is defined as change over time The theory that all organisms on Earth are related by common ancestry and that they have changed over time (adapted) mostly because of natural selection.The theory that all organisms on Earth are related by common ancestry and that they have changed over time (adapted) mostly because of natural selection. Charles Darwin is one of the most famous scientists associated with the theory of evolutionCharles Darwin is one of the most famous scientists associated with the theory of evolution

Darwin’s voyage

Darwin’s interest Darwin’s observations and research played an important role in the development of the theory of evolution that is still widely accepted today Darwin’s observations and research played an important role in the development of the theory of evolution that is still widely accepted today During his voyage on the U.S.S. Beagle, he would collect specimens from the different areas he visitedDuring his voyage on the U.S.S. Beagle, he would collect specimens from the different areas he visited He was fascinated to see the variety in the different plants and animals that he studiedHe was fascinated to see the variety in the different plants and animals that he studied

He did notice one similarity: All of the organisms he observed were well suited (well matched) to their environment

Beaks of finches The finches beaks have adapted and naturally selected for over time based on what they eat The finches beaks have adapted and naturally selected for over time based on what they eat

Adaptation An adaptation is any inherited characteristic that increases an organisms chance for survival Adaptations can be physical or behavioral and can be passed from generation to generation The process of becoming better suited to the environment

Different types of adaptations: Genetic adaptation – always genetically controlled (ex: 5 fingers, giraffe’s neck)

Different types of adaptations: Physiological adaptation – change in the reactions; can be genetic or not (ex: acclimation to altitude or climate, coat color change during seasons)

Different types of adaptations: Behavioral adaptation – change in behavior; can be genetic or not (ex: chimps using sticks to catch termites, bears eating garbage)

Survival of the fittest The ability of an individual to survive and reproduce is called fitness The ability of an individual to survive and reproduce is called fitness Adaptations that help an animal become more fit to survive and reproduce more successfully are commonly selected Adaptations that help an animal become more fit to survive and reproduce more successfully are commonly selected This is known as survival of the fittest This is known as survival of the fittest

Survival of the fittest is also known as natural selection

Over time, natural selection will change the characteristics of a population, increasing the fitness of that population

Proof? You want proof? Evidence of evolution through adaptation and natural selection can be found in: Evidence of evolution through adaptation and natural selection can be found in: the fossil record – the fossil record – Geographical distribution (different animals evolve similarly because of the same environmental factors) – Homologous structures – Similarities in early development of embryos

Fossil Record

Geographical Distribution

Homologous structures

Development of embryos

TODAY… Evolution is widely accepted by the scientific community Theories are constantly changing based on new evidence (mitochondrial DNA/rapid evolution…) Evolution is still occurring Many species are becoming extinct because they cannot evolve as fast as humans are changing the environment. Humans are “meddling” with evolution through artificial selection (fruit, dogs…)