How can reproductive isolation lead to speciation? SPONGE How can reproductive isolation lead to speciation?

KEY CONCEPT Evolution occurs in patterns.

Main Ideas Evolution through natural selection is not random Species can shape each other over time Species can become extinct Speciation often occurs in patterns

Evolution through natural selection is not random. Natural selection can have direction. The effects of natural selection add up over time.

Both used to propel through water. Convergent evolution describes evolution toward similar traits in unrelated species. Shark: fish, tail is vertical Both used to propel through water. Dolphin: mammal, tail is horizontal

Divergent evolution describes evolution toward different traits in closely related species. Ex: The Kit fox and Red fox evolved from a common ancestor while adapting to different environments. Kit fox: Desert regions Red fox: temperate regions

Species can shape each other over time. Two or more species can evolve together through coevolution. evolutionary paths become connected species evolve in response to changes in each other Beneficial: Bumble bees and the flowers they pollinate have coevolved to depend on each other for survival.

Coevolution can occur in beneficial relationships. Stinging ants and the Bull-thorn acacia plant have coevolved together. The ant eats the nectar inside the thorns and sting any other organisms that try to eat the leaves. The ant gets food and the plant gets protections (mutualism)

Coevolution can occur in competitive relationships, sometimes called evolutionary.

Set up Cornell Notes on pg. 27 Topic: 11.6 Patterns in Evolution Essential Question: What are some of the causes of background and mass extinctions? What is the major difference between a background and mass extinction? 11.6 Patterns in Evolution 2.1 Atoms, Ions, and Molecules What are some of the causes of background and mass extinctions? What is the major difference between a background and mass extinction?

Species can become extinct. Extinction is the elimination of a species from Earth. Often occurs when a species as a whole is unable to adapt to change in its environment

Background extinctions occur continuously at a very low rate. occur at same rate as speciation usually affects a few species in a small area caused changes in environment Ex: The Iberian lynx is the most endangered feline. May only be 200 left.

Mass extinctions are rare but much more intense. destroy many species at global level thought to be caused by catastrophic events at least five mass extinctions in last 600 million years

Dinosaurs 1 5 3 4 2

A pattern of Episodic speciation exists in the fossil record episodes of speciation occur suddenly in geologic time followed by long periods of little evolutionary change Usually occur after a mass extinction Happens because new species inhabit environments that have been cleared of life