1. 10.3 Theory of Natural Selection LEQ: What is evolution? Activator: Answer the following Q’s on a separate piece of paper after completing your quiz. –How are species related to the concept of biodiversity? –Classify a human using the Linnaean system (see 12.6 for hints). Name each taxon name from most general to most specific. Key terms – evolution, variation, natural selection, fitness, adaptation

2. 10.3 Theory of Natural Selection Evolution explains the unity and diversity of life The characteristics (structures) of members of the same species can evolve or change over time in response to changes in the environment: –Variation –Selection –Time

3. 10.3 Theory of Natural Selection Darwin observed differences among island species. Variation describes the differences in a physical structure. –Variants must be heritable –Galápagos tortoises that live in areas with tall plants have long necks and legs.

4. 10.3 Theory of Natural Selection In nature, selection constantly sorts through variation. The environment kill individuals of every generation who have traits that do not aid in survival/reproduction Survivors have offspring who inherit parental traits

5. 10.3 Theory of Natural Selection Darwinian fitness measures evolutionary outcomes. Because of selection, reproductive success varies Fitness measures the reproductive success of an organism with an inherited variant: who reproduces?

6. 10.3 Theory of Natural Selection Discussion: Discuss why only those that survive long enough to reproduce affect the characteristics of future generations of a species. Ancient hands ancient tools: –How did the evolution of our hands also lead to the “evolution” of ancient tools? –Long fingers or short fingers?

7. 10.3 Theory of Natural Selection Updates: Quizzes continue tomorrow: cladograms, evolution Homework: –reading 10.1-10.2 –Finish making of a theory questions due tomorrow Empty folders! The missing….

8. 10.3 Theory of Natural Selection 1) The basic unit of any biological system is a. an atom. b. DNA. c. the cell. d. a species 2) The body's internal environment must stay a. away from sudden outside temperature changes. b. the same as its external environment. c. exactly the same at all times. d. within narrow ranges that support human life.

9. 10.3 Theory of Natural Selection 3) Which phrase best describes Earth's biodiversity? a. greater where temperatures are most variable b. greater toward Earth's poles c. greater according to energy needs d. greatest near the equator 4) Which of the following taxa contains the least members? a. species b. order c. class d. phylum

10. 10.3 Theory of Natural Selection An adaptation is a structure that allows an organism to better survive in its environment. –Species must adapt to their environment. –Why? Because…extinction is the alternative. wrist bone five digits

11. 10.3 Theory of Natural Selection How has the medium ground finch population changed after the drought?

12. 10.3 Theory of Natural Selection Summary “What may at first seem contrived or even ugly may be the best solution that natural selection could devise.” Francis Crick What is natural selection? Why must there be variation in a population in order for natural selection to occur?

13. 10.3 Theory of Natural Selection Review Question: Which of the following describes a negative feedback loop: –A) labor contractions increasing in frequency –B) Lactation beginning during pregnancy –C) Running a fever –D) Sweating to cool the body

14. 10.3 Theory of Natural Selection Fitness has many components that interact Fitness can be broken into several life history traits, –size at birth –growth pattern –age and size at maturity –number, size, and sex of offspring –age-, stage- or size-specific reproductive effort –age-, stage- or size-specific rates of survival –lifespan Certain combinations can evolve in such a way that optimizes reproductive success

15. 10.3 Theory of Natural Selection Review Question: Which best describes typical behavior at a set point: –Sweating profusely –Shivering at the bus stop –Hunger/low blood sugar –None of the above