Lecture Notes 05/05/2016

Natural Selection Diversity of Life Unit Module 2 ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 2

Review Evodots and PBS Check your notes along with Ms. P ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 3

Modeling Natural Selection Simulation Peppered Moth, Biston betularia, in England ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 4 Light-colored moths blended in with light colored lichen on their tree bark habitat. Eaten by birds. Industrial Revolution killed the lichen on the tree bark. The tree bark became darker due to soot from pollution. Over time, the population of dark-colored moths increased. How and why did this happen? Early 1700s Mid 1700s Mid 1800s

Principles of Natural Selection ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED There must be variation within a trait. -The color of the moths. 2. The variation must be heritable (passed on to offspring). -The color of the moths was passed from parent to offspring. 3. In every generation, more offspring are produced than can survive. -The predators “ate” the moths faster than they could reproduce. 4. The individuals that survive to reproduce are those with the trait most favorable (adaptive) to the environment. - Over generations, the population of moths with the color that matched the background increased.

Populations change, not individuals The “average” characteristic or other measure of the population changes over generations. ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 6 Frequency Characteristic average, 1 st gen. These individuals die without reproducing average, 2nd gen. These individuals die without reproducing average, 3rd gen. average, 50 th gen. These individuals survive to reproduce

Which is an example of natural selection? 1.Beetles on a diet There have been 2 years of drought in which there are few plants that these beetles can eat. All the beetles have the same chances of survival and reproduction. Because of lack of food, the beetles in the population are a little smaller than the preceding generation of beetles. 2. Beetles of a different color In the population, 90% of the beetles have the genes for bright green coloration, and 10% of them have a gene that makes them brown. Over time, the environment became more brown. Many generations later, things have changed: 30% of the beetles are bright green and 70% are brown. ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 7 Example edited from:

Cornell Check-in!!! Check your notes with your Partner….Make updates as needed Answer this together: What was selected for in the moths? What was selected against? ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 8

Proposed a mechanism for evolution: Natural Selection Published The Origin of Species in 1859 to describe his theory Starting with artificial selection, then building a case for natural selection ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 9 Charles Darwin (1809 – 1882)

Darwin: The Early Years ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED Disinterested in school Quit medical school because it bored him and he couldn’t stand surgeries Studied to become a clergyman so he could pursue his interest in nature His father remarked: “You care for nothing but shooting, dogs, and rat-catching, and you will be a disgrace to yourself and your family.”

Darwin: HMS Beagle After finishing school, at age 22 Darwin left on a voyage as the ship’s naturalist. ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED The exploratory voyage was planned to be 2 years long, but ended up lasting 5! Darwin was seasick the whole time.

Darwin’s Finches ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED Collected 31 finches from 3 islands in the Galpagos Darwin observed the birds foraging together He did not think they were all related This observation “Planted the seed” that eventually germinated into his Theory of Natural Selection

©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 13

Subsequent work on the finches of the Galpagos has shown beak size to be associated with different types of food Examples: Thick beak for eating hard seeds Pointy beak for getting grubs out of holes in trees Rounded beak for eating buds/fruit Darwin’s Finches ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 14

Connection to Genetics ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED The allele for a gene that increases an organism’s fitness will gradually predominate in the gene pool (and in the organism’s phenotypes). Gradual process; there are still elements of randomness at work. o Example: Allele: pointy Gene: beak shape

The Principles of Natural Selection State That: a.Individuals change their traits during their lifetime and pass these traits on to their offspring. b.Individuals with advantageous traits survive to reproduce and pass on their genes to offspring. c.Individuals change their genes and then pass these better genes on to their offspring. d.Individuals are always mutating to get better. ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 16

But on What Time Scale? Evolution can occur more quickly than you think. Bacterial Resistance Video ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 17

Brainstorm: How Does Natural Selection Affect our Everyday Lives? ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED. 18

Another Mechanism: Sexual Selection ©2013 EDUCURIOUS PARTNERS. ALL RIGHTS RESERVED Definition: Any characteristic that affects an organism’s ability to secure mates. Bowerbird Video Affects genes and resulting phenotypes. Can sometimes work in opposition to natural selection. o Example: The peacock’s large tail attracts mates, but could increase predation risk.