Darwin and Evolution

DARWIN'S VOYAGE

• WHAT DID DARWIN OBSERVE ?
• - In biology, evolution refers to the process in which populations gradually change over time. A population is all the individuals of a species that live together in area. A species is a group of closely related organisms that can produce fertile offspring.
• - Darwin formed a theory about how biological evolution could happen.
• - Darwin made his most influential observations on the Galapagos Islands of South America
• DIFFERENCES AMONG SPECIES
• - Darwin collected birds from the Galapagos Islands and nearby islands
• - The most obvious difference between the finches was the shape of their beaks.
• - Birds with shorter, heavier beaks could eat harder foods than those that had skinnier, thinner beaks. Based on these observations, Darwin wondered if the birds had evolved from one species of finch.

Darwin's Hortawork

• WHAT OTHER IDEAS INFLUENCED DARWIN ?
• - Darwin was influenced by ideas about how traits are passed on its selective breeding, Earth's history, and the growth of populations.
• ORGANISMS PASS TRAITS ON to OFFSPRING
• - A trait is a form of inherited characteristics.
• - The practice by which humans select plants or animals for breeding based on desired traits is artificial selection.

NATURAL SELECTION

• WHAT ARE THE FOUR PARTS OF NATURAL SELECTION ?
• - Natural selection is the process by which organisms that inherit advantageous traits tend to reproduce more successfully than the other organisms do.
• GENETIC VARIATION
• - Within a species there are natural differences, or variations, in traits.
• - Genetic variations can be passed from parent to offspring.
• -The more genetic variation a population has, the more likely it is that some individuals might have traits that will be advantageous if the environment changes.
• SELECTION
• - These resources include food, water, space and, in most cases, mates for reproduction.
• - As a result, the trait is "selected," or becomes more common in the next generation of offspring.
• ADAPTION
• - An inherited trait that helps an organism survive and reproduce in its environment is an adaption.

WELL - ADAPTED

• HOW DO SPECIES CHANGE OVER TIME ?
• - An incredible diversity of life exists because species have changed over time, or evolved.
• - An early from of a species, called an ancestor, may give rise to many new descendent species over time.
• WHY IS ADAPTION IMPORTANT FOR SURVIVAL ?
• - The traits that help an organism survive depend on both the needs of the species and environmental factors.
• SPECIES NOT ADAPTED TO THE ENVIRONMENT MAY GO EXTINCT
• - Changes in environmental conditions can affect the survival of individuals with a particular trait.
• - Extinction is when all of the members of a species have died. Competition, new predators, and the loss of habitat are environmental pressures that can limit the growth of populations and could lead to extinction. The fossil record is a record of the things that have lived in a particular location. It shows that many species, like the dinosaurs above, have gone extinct in the course of the history of life on Earth.
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