1. The Basics of Evolution
Chapter 15

2. The idea of evolution
Came from observations made by Charles Darwin when he visited the Galapagos Islands.
Observed that organisms differed slightly from one another in different regions
Tortoises, finches
Evolution –
Change in a species over time… new types from existing types OR a hertitable change in a population between generations

3. What evolution is The concept that species change over time
The theory that explains this process is called natural selection, which includes many variables, such as “fitness”, environment, population numbers, predators, genetics, and more
Organisms change and adapt based upon biotic and abiotic factors; this can lead to new species
Evidenced in antibiotic resistance, new viruses, bird groups, and many more

4. What evolution is not: Misconceptions
Humans did not evolve from monkeys; however, scientists do think that they shared a long-ago common ancestor
Completely random: evolution can be affected by many environmental factors
An explanation of how life began; instead, it is an explanation of how organisms change over time

5. Lamarck’s incorrect idea

6. Age of Earth
Until the 1700’s, scientists believed that species never changed. Then, they saw evidence otherwise:
Geology: Rock layers date time much farther back: 4.5 billion years ago, as measured by carbon dating
Fossils: Fossils found in rock layers are dated back to early times
Fossilized organisms resembled today’s organisms, but with differences

9. Natural Selection A way to explain how species change over time
Ways that natural selection might work:
Overproduction – environment prevents survival of all
Genetic variation – different trait in a population
Struggle to survive – competition in environment
Differential reproduction – best adapted will reproduce

10. Anatomy & Embryology
Homologous structures – most recent common ancestor shared the same basic structure
Ex: human arm, penguin, alligator, bat
Analogous structures – closely related functions without a shared common ancestor
Ex: wings of birds, moths, and bats

11. Homologous structures

12. EVOLUTION Homologous Vestigial Molecules Structures Structures Forelimbs Pelvis Proteins Birds Whales Chickens Mice Dolphins Vertebrates Frogs Humans Rhesus monkeys Lampreys

13. Diagramming to show relationships
Phylogenetic tree – diagram showing relationships of common ancestors, based upon genetics, anatomy, or other relationship information
Adaptive radiation – a new population colonizes a new environment by changing to fill many places in the ecosystem

14. Cladistics
Using phylogeny (shared ancestry) to show how a shared characteristics is found within organisms.
A way to show evolutionary relationships around a specific feature (feathers, arm bones, seeds, etc)

15. Cladogram

16. Cladogram – Part 2

17. Cladogram Analysis
Today, with the advances in genetics and biochemistry, biologists can look more closely at individuals to discover their pattern of evolution, and group them accordingly - this strategy is called EVOLUTIONARY CLASSIFICATION
CLADISTICS is form of analysis that looks at features of organisms that are considered "innovations", or newer features that serve some kind of purpose. (Think about what the word "innovation" means in regular language.) These characteristics appear in later organisms but not earlier ones and are called DERIVED CHARACTERS.
PART I - Analyze the Cladogram in the previous slide.
In the sample cladogram, each letter on the diagram points to a derived character, or something different (or newer) than what was seen in previous groups. Match the letter to its character. Note: this cladogram was created for simplicity and understanding; it does not represent the established phylogeny for insects and their relatives.

18. Write the letter to match the evolutionary development
1. ______ Wings 2. ______ 6 Legs 3. ______ Segmented Body 4. ______ Double set of wings 5. ______ Jumping Legs 6. ______ Crushing mouthparts 7. ______ Legs 8. ______ Curly Antennae

20. How species evolve: gradualism vs. punctuated equilibrium