EVOLUTION and NATURAL SELECTION

Evolution = change over time Remember the Earth is estimated to be _______________ years old! 4.6 Billion

Charles Darwin 1831 Sailed to Galapagos Islands Noticed that species diversity was greater than we thought. Each plant and animal was adapted to its special environment on the island.

Darwin’s Finches Each island had its own type of finch that was clearly different from finches on other islands The different beak structures were adapted to the finch’s source of food.

Darwin’s Summaries 1. Organisms differ; variation is inherited 2. Organisms produce more offspring than survive 3. Organisms compete for resources 4. Organisms with advantages survive to pass those advantages to their children 5. Species alive today are descended with modifications from common ancestors

Environmental stress The dance of survival Natural selection Darwin’s proposed theory that organisms better suited for an environment are more likely to survive and pass on their traits is called? Environmental stress The dance of survival Natural selection Founder’s effect

Natural Selection results in: Adaptation – trait that gives advantage Behavior – action that gives advantage Extinction – all species die Speciation – new species forms

Adaptation Inherited characteristic that increases an organism’s chance of survival

Mimicry the similarity in appearance of one species to another that protects one or both. Example: hoverflies look like stinging wasps

Camouflage when a species resembles its surroundings Flounder with rocks on sea floor grasshopper

Behavior

Extinction Speciation Over time the life on Earth changes. Nature selects individuals in a population that are the most “fit” and those pass on their genes. If the entire species die it is called ________________. If a new species forms it is called ______________. Extinction Speciation

Extinction

SPECIATION Is the formation of new species. Occurs through 4 different mechanisms.

ISOLATING MECHANISMS… BEHAVIORAL ISOLATION- Capable of breeding but have difference in courtship rituals

Bird of Paradise http://www.youtube.com/watch?v=7dx2CUMtZ-0

ISOLATING MECHANISMS… 2. GEOGRAPHICAL ISOLATION – separated by geographic barriers. Rivers Mountains Oceans

These squirrels live on opposite sides of the Grand Canyon These squirrels live on opposite sides of the Grand Canyon. This is an example of geographical isolation.

ISOLATING MECHANISMS… 3. TEMPORAL ISOLATION – 2 or more species reproduce at different times. Like Winter and Spring

ISOLATING MECHANISMS… 4. REPRODUCTIVE ISOLATION- when members of 2 populations can no longer interbreed For example, damselfly penises only “fit” with the correct mate.

Speciation causes Biodiversity

Artificial Selection The intentional breeding for certain traits. This chihuahua and great dane show the wide range of dog breed sizes created using artificial selection.

Tigon Result of male tiger and female lion mating incaptivity. Offspring are infertile. Separated both geographically and ecologically.

Liger Result of male lion and female tiger mating in captivity. Offspring are infertile.