Evolution

Question Using two complete sentences define Natural Selection. How does Natural Selection lead to changes in populations?

Words not to use!! Need Want Try Goal Better

Earths history What is the cause of these mass extinctions? Extreme changes in the environment! Why do some organisms survive while others die out? Organisms with favorable traits for new environment survive while organisms with unflavored traits will die.

Earths History Throughout earths history there have been the appearance and disappearance (extinction) of species. What is the cause of these mass extinctions? Why do some organisms survive while others die out?

What is Evolution? The theory (what does this mean??) that organisms gradually and slowly change over time into new species. Results from natural selection acting on genetic variation present among individuals of a species Natural selection is the Mechanism of evolution!!

Evolution by Natural selection Is a result of Random and Nonrandom processes. Mutations (changes In DNA) are random events that occur and create new genetic information. Natural selection is NOT random. As the environment changes specific traits are more favorable.

Natural Selection Sources of variation? mutations and genetic recombination (mutations can be good, bad, or indifferent) When could genetic recombination occur? SEXUAL REPRODUCTION Recombination occurs when chromosomes exchange different information during “crossing over” in meiosis. This leads to new combinations of genes which were not found in previous generations

SEXUAL reproduction Think back to the pros and cons of asexual and sexual reproduction. Sexual reproduction increases variation among offspring. This variation increases the chances that when the environment conditions change at least some offspring have a chance to survive.

Genetic recombination Homologous chromosomes showing crossover during meiosis I Fertilization, the combination of two different haploid genetic sets causes unique offspring

Theories of Evolution Darwin gets all the credit, but there were others! 1766 Georges Buffon (French)-said that some fossil forms may be ancient versions of living species

Theories of Evolution Jean Baptiste Lamarck (1809-French) Organisms constantly strive to improve themselves and become more advanced Principle of Use and Disuse -This effort to improve causes the most used body structures to develop, the unused structures waste away Inheritance of acquired characteristics -Once the structure is modified, the modification is inherited by the organism’s offspring

Use and Disuse Examples from the reading? Snake loosing its legs Giraffe stretching its neck Others?

Theories of Evolution continued… THE MAN! Charles Darwin Infamous for his research on the H.M.S Beagle, using organisms from the Galapagos Islands to develop the theory of natural selection He was 22 years old when he left on the Beagle!!! - Taylor Swift’s age

Survival Of the FITTEST? Fitness (not talking about exercise) In evolution Fitness refers to an organisms ability to survive and reproduce offspring. High fitness- lots of offspring long life. Low fitness- death Fitness changes with the environment!

Darwin’s Theory of Natural Selection individuals with traits best suited to the environment are the ones that reproduce and pass their traits on to their offspring. Those organisms less fit tend to die before they are able to reproduce. Their genes are not passed on. Survival of the fittest This leads to an accumulation of favored traits in the population over generations (evolution).

4 principals of natural selection 1.Overproduction - more offspring are born than survive 2. Genetic Variation - there is variation in the population 3. Struggle to Survive - organisms with suitable variations will survive and reproduce 4. Differential Reproduction - suitable variations are passed on to offspring

Mice in that area were brown to blend in with the sand (camouflage) Example of Evolution: Pocket mice in Nevada!! About a thousand years ago lava flows in Nevada caused large areas to be covered in black rock. Mice in that area were brown to blend in with the sand (camouflage) This is an example of natural selection! Survival of the fittest

Within a thousand years all the mice on the rocks have black fur. Example of evolution On the new black rock the brown mice stood out (easy picking for predators) Within a thousand years all the mice on the rocks have black fur.

SO what happened? Where did the trait for black fur come from? A RANDOM MUTATION ( where can those come from?) What caused the trait to the main fur color in mouse populations on black rock? NATURAL SELECTION

In Darwin We Trust Evidence: he noted that the of several different types of finches were adapted to the type of food they ate. Darwin hypothesized that the finches strayed from the mainland and then diversified on the different islands. Through his research Darwin composed his theory of evolution (1840s). He delayed publication (published 1859) Why would he delay??

Wallace: the competition Alfred Wallace – He also developed a theory of evolution based on natural selection. He sent a memoir concerning his ideas to Darwin in 1858. This prompted Darwin to publish his book. Peer pressure at its best!!

H.M.S. Beagle voyage: 5 years at sea

Evidence For evolution ____________________________

Stop and Think Scientist found a new kind of fox living in Canada. The area had a lot of forest cut down 100 years ago and is a brown barren land. The fox is a very dark brown color. Using Darwin's ideas about natural selection and evolution explain how that could happen. Make sure you answer the following questions in your answer. Where did the new fur color trait come from? How and why did it become the main fur color in that population.

Answer example  The trait of brown fur came from a random mutation in one fox. The brown fur was good camouflage in that environment. (Why?)-This mutation increased its fitness. This increased the foxes ability to survive and reproduce. (how?)- The fox then passes that trait on to its offspring. Over many generations the brown fur was so advantageous that all the foxes in that area now have brown fur.