Evolution What role does the environment play in an organism’s survival, reproduction and evolution?

FOCUS Study each of the living things above. Describe the ecosystem that each lives in. What traits/characteristics do each of the living things have that make it suited to live in its ecosystem? Do you think those traits always existed?

Evolution and Natural Selection The processes of evolution have acted to change earth over time. (1.5 million years to be exact) Evolution = change over time. Biological Evolution = a change in a population’s gene pool over time. A gene is a sequence of DNA that codes for a particular trait.

Mechanisms of Biological Evolution Mutation: accidental changes in DNA that can give rise to genetic variation. Migration: movement of individuals in or out of a population thus removing or adding genetic variation. Genetic Drift: biological evolution that occurs by chance…like a forest fire, hurricane, etc. Certain individuals are separated and develop separate characteristics. Natural Selection: the process by which traits that improve an organism’s chances for survival and reproduction are passed on more frequently to future generations than those that do not.

2 1 Migration: movement of individuals in or out of a population thus removing or adding genetic variation. Mutation: changes in DNA that can give rise to genetic variation. 3 4 Natural Selection: the process by which traits that improve an organism’s chances for survival and reproduction are passed on more frequently to future generations than those that do not. Genetic Drift: biological evolution that occurs by chance…like a forest fire, hurricane, etc.

Conditions of Natural Selection Natural selection is a simple concept that offers a great explanation for how things are in nature. Organisms produce more offspring than can survive. Individuals of a species vary in their characteristics. Individuals vary in their fitness. Fitness = reproductive success. Adaptations are heritable traits that increases chances for survival. In 1859, Charles Darwin published, On the Origin of Species, where he presented the scientific theory of Natural Selection.

Survival of the Fittest Organisms produce more offspring than can survive. Individuals vary in fitness, or reproductive success. Survival of the Fittest The fish with the best traits for survival will live. That fish will reproduce, thus creating more fish with that desirable trait. “Fit”ness is defined by the environment…as it changes, so must the things living in it. BEST EXAMPLE…as Earth changed, organisms had to change with it to survive…or evolve! That evolution was in response to the changing world around them!

What is the Difference Between Natural Selection and Artificial Selection? Environmental conditions create variations in organisms. Selection occurs naturally. “Survival of the fittest” Artificial Selection Artificial breeding of organisms to produce the most desirable traits. The process of selection conducted under human direction Dogs and plants!

Speciation Imagine this… 2 islands…pretty close together. On each island a specie of squirrel specific to the island. They seem similar, but they have enough similarities that it seems odd. How can they be related? They live in 2 different places and never interact?

Speciation and Extinction Speciation – the process by which new species are generated. Most often as a result of geographic isolation. Over time led to the creation of many different species on Earth. Extinction – the disappearance of a species from Earth. Occurs when environmental conditions change rapidly and organisms can’t adapt quickly enough. 99% of the species that ever lived are now gone.