Natural Selection SPI 0807.5.3 Analyze data on levels of variation within a population to make predictions about survival under particular environmental conditions.

Natural selection Process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals. Survival of the fittest!! Survival Means: Living and passing on your traits to offspring (this ensures your species will survive)

Over time Organisms inherit characteristics/ traits from their parents (inherited variation) The characteristics of a population can change over time The change of characteristics in a population is due to natural selection

Example Sea turtles lay multiple eggs at one time Not all of the babies will make it to the ocean Not all the babies will survive into adulthood Not all the adults will reproduce Only the offspring with the best traits will survive to pass on their traits to their offspring.

Four Parts Over production Genetic Variation Struggle to Survive Successful Reproduction

1. Overproduction More offspring are born than will survive to become adults Example: Sea turtles Salmon Frogs Dogs Birds

2. Genetic Variation w/in Population Three Causes of variation: 1. Diversity of genetic traits from sexual reproduction 2. Diversity of genetic traits from mutations. 3. Changing environmental conditions. Different characteristics improve chances of survival and reproduction Example: albino alligators, rabbits with bigger ears, more aggressive lion, runt of the litter

3. Struggle to Survive Environments may not have enough food or water to support all born organisms Some organisms may not be able to find food, or a mate. Only the organisms with the best adaptations will survive Example: zebra killed by lion, buck wins the fight for a mate vs. the losing buck

4. Successful Reproduction This is the key to natural selection. Organism with the better adaptations to survive will more likely reproduce. Less will adapted organisms will likely die early or produce few offspring Example: bird that cannot build an adequate nest will raise fewer offspring