The Organization of LifeSection 2 Quick Review Through what process does evolution occur? –Natural Selection Who’s idea was this? –Charles Darwin What happens to the animals when they evolve? –Adaptations that make them more likely to survive are passed on to future generations

The Organization of LifeSection 2 Coevolution When two species evolve in response to long-term interactions and dependence on each other is called coevolution. –Co- means together –Examples: Bumblebees and Flowers Hummingbirds and flowers Hawaiian Honeycreeper and flowers

The Organization of LifeSection 2 Hummingbirds and Flowers The flowers have nectar suited to the birds' diet, their color suits the birds' vision and their shape fits that of the birds' bills. The blooming times of the flowers have also been found to coincide with hummingbirds' breeding seasons.

The Organization of LifeSection 2 Coevolution The honeycreeper’s adaptation is a long, curved beak. The plant has two adaptations: –The first is the sweet nectar, which attracts the birds. –The second is the flower structure that forces pollen onto the bird’s head when the bird sips nectar.

The Organization of LifeSection 2 Evolution by Artificial Selection Artificial selection is the selective breeding of organisms, by humans, for specific desirable characteristics. Dogs have been bred for certain characteristics. Fruits, grains, and vegetables are also produced by artificial selection. Humans save seeds from the largest, and sweetest fruits. By selecting for these traits, farmers direct the evolution of crop plants to produce larger, sweeter fruit.

The Organization of LifeSection 2 Artificial Selection

The Organization of LifeSection 2 Artificial Selection

The Organization of LifeSection 2

The Organization of LifeSection 2 Evolution of Resistance Resistance is the ability of an organism to tolerate a chemical or disease-causing agent. Sometimes humans cause organisms to evolve unwanted adaptations. –Example: Insects that are resistant to pesticide Bacteria that are resistant to antibiotics

The Organization of LifeSection 2 Pesticide Resistance A pesticide sprayed on corn to kill grasshoppers, for example, may kill most of the grasshoppers, but those that survive happen to have a gene that protects them from the pesticide. These surviving insects pass on this resistant gene to their offspring. Each time the corn is sprayed, more resistant grasshoppers enter the population. Eventually the entire population will be resistant, making the pesticide useless.

The Organization of LifeSection 2 Pesticide Resistance

The Organization of LifeSection 2 Why do things become resistant? An organism may be resistant to a chemical when it contains a gene that allows it to break down a chemical into harmless substances. Humans promote the evolution of resistant populations by trying to control pests and bacteria with chemicals. This is becoming a big problem!!! –MRSA –Antibacterial Soaps