2.6 Evolution and Adaptation 

The theory of natural selection was developed by Charles Darwin and first presented in his book Origin of Species published in 1859.

^^Microevolution:^^ genetic changes within a species; natural selection/adaptations

• Ex: varieties of apples or dogs

^^Macroevolution:^^ genetic changes that give rise to new species

• Highly debated and controversial, particularly about origin

EVOLUTION IS NOT NATURAL SELECTION!

Natural Selection

^^Natural Selection:^^ Organisms that are best adapted to an environment survive and reproduce more than others

Occurs in four steps:

1. Overproduction
2. Variation
3. Competition
4. Selection

^^Fitness:^^ Differential ability to survive and reproduce

^^Adaptation:^^ Any behavioral or physical characteristic that increases fitness

The Theory of Natural Selection

1. There is a struggle for existence among organisms.
2. There is physical and behavioral variation in living organisms (even within the species level).
3. Organisms with higher fitness (more helpful adaptations) are more likely to survive: “Survival of the Fittest.”
4. Over time, a “natural selection” will ensure that certain characteristics appear more and more often as they are passed through generations. Entire species can change over time in this way.

^^Common descent/ Descent with modification:^^ This theory states that living species have descended, with changes, from other species over time.

Geological processes affect evolution

1. Locations of continents influence climate and habitats
2. Movement of continents allow for dispersal, speciation, extinction
3. Earthquakes can isolate populations, leading to speciation
4. Volcanoes can destroy habitat and cause extinction
5. Asteroid impacts can cause widespread extinction, climate change

Climate Change processes affect evolution

6. Ice ages/warming periods cause migration, extinction, new niches