2. EVOLUTION: PROCESSES & PATTERNS

3. BIOLOGY EOC BENCHMARK SC.9.12.L.15.1 Explain how the scientific theory of evolution is supported by the fossil record, comparative anatomy, comparative embryology, biogeography, molecular biology, and observed evolutionary change

4. VIDEO: Simpson Evolution Why is Homer evolving?

5. Convergent Evolution Different organisms that live in similar environments become more alike in appearance and behavior. Environment selects similar adaptations in unrelated species. Organisms develop analogous structures (same function, but different origins)

6. Coevolution Two species evolve together. There is a mutual evolutionary influence between two species. The species have a symbiotic relationship (interaction between members of two populations). Example: - Birds and flowers

7. Divergent Evolution Ancestral species gives rise to a number of new species that are adapted to different environmental conditions and are less alike. Often occurs when a species colonizes a new environment. Also known as adaptive radiation.

8. Evidence for Evolution Fossil Records Biogeography Comparative Anatomy and Embryology Genetics Experimental Research

9. Fossil Record Dating methods have shown the age of the Earth – plenty of time for evolution to occur. Recent fossil discoveries have shown intermediate species, connecting species in a series Dinosaurs  Birds Land mammals  Whales Fish  Four-legged land animals

10. Biogeography The study of where organisms and their ancestors lived. Patterns in the distribution of both living and extinct species help us to understand how organisms evolved. Two kinds of patterns have been observed.

11. Biogeography Slight differences in environment produces variations among populations that eventually result in different species. Galapagos finches Chimps and bonobos

12. Biogeography Distantly related species that have similar traits often live in similar geographical areas

13. Comparative Embryology Similar embryonic stage of organisms that are very different as adults.

15. Anatomy Homologous Structures Analogous structures Vestigial Structures

16. Homologous Structures Structures that are shared by different species that have been inherited by a common ancestor Animal Forelimbs Opposable thumbs in primates Hooves in ungulates

17. Analogous Structures Body parts that serve similar functions, but may not have similar structures, that evolved independently from each other. Wings of insects and birds Evidence of the effect of selective pressures Bat wing Fly wing

18. Vestigial Structures Body parts that have lost most or all of their original function. Appendix in humans Femur in snakes Hip bones in dolphins

19. Genetics and Molecular Biology

20. Comparative Biochemistry Similar DNA sequences Similar gene segments of the DNA code for similar traits closely related species

21. Experimental Research Is evolution testable? Galapagos finches – Studied for decades (>35 years) Drosophila (fruit flies) – reproduce very quickly Bacteria – antibacterial resistance

22. THE EVOLUTIONS OF POPULATIONS THERE ARE FOUR MECHANISMS THAT CAN GIVE RISE TO EVOLUTION: 1.MUTATION 2.GENETIC DRIFT 3.MIGRATION (Gene Flow) 4.NATURAL SELECTION Greatly and quickly seen in isolated populations like those on islands. - Allele frequency will change over generations; situations/ENV will favor one allele over another - Those populations at equilibrium are not evolving - Species with more genetic diversity will adapt better to environmental changes

23. GENETICS OF WHITE BENGAL TIGERS In nature, White Bengal tigers arises from the mating of two Bengal tigers with recessive genes for the white color of fur. The gene is recessive and has the effect that offspring (cubs / kittens) only become white if they inherit the recessive gene from both parents. It is the same principle as with brown and blue eyes. The inbreeding producing all these White tigers is neither good nor healthy for the tigers. In nature White tigers have, at least theoretically as there probably aren’t any, less of a chance of surviving than normal colored tigers due to their lack of camouflage compared to the normal Yellow Tigers. Below is a very simplified illustration (Fig 1) of how the transfer of genes coding for fur color works. Consider to yellow Bengal Tigers mating. If they are both carriers of the recessive gene there's a 25 percent chance that their cubs will be white. If a white and a yellow Bengal tiger mates there's a 50 percent chance that the offspring will be white. The chances of getting more White tigers can be enhanced by letting tigers that are related mate. This is and example of inbreeding.

24. TIGER POPULATION THE EVOLUTIONS OF POPULATIONS Proportion of orange fur- pigment alleles in the population Proportion of white fur-pigment alleles in the population Allele frequencies: Evolution is a change in the allele frequencies of a population over time. For example, a change in the proportion of pigment alleles in the population of tigers means that evolution has occurred.

25. Normal phenotype MUTATION A mutation can create a new allele in an individual. When this happens, the population experiences a change in its allele frequencies and, consequently, experiences evolution. MECHANISMS OF EVOLUTION EVOLUTIONARY CHANGE: MUTATION Despite mutation’s vital role in the generation of variation, mutations almost always cause early death or lower the reproductive success of an organism.  DNA Mutagen Mutated protein Mutated phenotype Mutated base- pair sequence Normal base- pair sequence Normal protein #1

26. Mutations Are rare because you have self correcting enzymes Natural Process that produces genetic diversity Not all mutations are bad Some won’t affect the body at all Blood types/ear lobes Some are advantageous (thumb) Brain Pop: Genetic Mutations

27. POPULATION BEFORE GENETIC DRIFT Allele frequencies: MECHANISM FOR EVOLUTION - GENETIC DRIFT population can experience random changes in allele frequency that do not influence reproductive success which leads to evolution FIXATION Genetic drift leads to fixation when an allele’s frequency becomes 100% in a population. If this occurs, there is no longer genetic variation for the gene. POPULATION AFTER GENETIC DRIFT There are now more recessive alleles in the population than before. REPRODUCTION In this example, a heterozygous couple (Cc) could have two children that are homozygous recessive (cc), causing an increase in the proportion of recessive alleles in the population. cleft chin (dominant) smooth chin (recessive) Neither allele is related to reproductive success. Inheritance is based solely on chance.

28. 5 digits per hand (recessive) NEWLY FOUNDED POPULATION The new population will be dominated by the genetic features present in the founding members. SOURCE POPULATION Allele frequencies: A group of individuals may leave a population and become the founding members of a new, isolated population. >5 digits per hand (dominant) AMISH GENETIC DRIFT - FOUNDER EFFECT The founding members of a new population can have different allele frequencies than the original source population and, consequently, the new population experiences evolution.

29. ARTICLE: The Amish and Founder Effect

30. GENETIC DRIFT - BOTTLENECK EFFECT Occasionally, famine or disease or rapid environmental change may cause the deaths of a large, random proportion of the individuals in a population. SOURCE POPULATION NEW POPULATION All cheetahs living today can trace their ancestry back to a dozen or so individuals that happened to survive a population bottleneck about 10,000 years ago!  EXTREME AND RAPID ENVIRONMENTAL CHANGE The new population will be dominated by the genetic features present in the surviving members. SOME CATASTROPHE Unless more individuals are introduced to the population, mating options will be limited thus decreasing variation in the gene pool (decreasing genetic diversity).

31. MECHANISMS OF EVOLUTION MIGRATION After a group of individuals migrates from one population to another, both populations can experience a change in their allele frequencies and, consequently, experience evolution. MIGRATION (GENE FLOW) 1 BEFORE MIGRATION Two populations of the same species exist in separate locations. In this example, they are separated by a mountain range. Population 1 Population 2 #3

32. 2 MIGRATION A group of individuals from Population 1 migrates over the mountain range. MECHANISMS OF EVOLUTION MIGRATION After a group of individuals migrates from one population to another, both populations can experience a change in their allele frequencies and, consequently, experience evolution. MIGRATION (GENE FLOW) Population 1 Population 2 #3

33. 3 AFTER MIGRATION The migrating individuals are able to survive and reproduce in the new population and they may experience evolutionary changes from population 1. MECHANISMS OF EVOLUTION MIGRATION After a group of individuals migrates from one population to another, both populations can experience a change in their allele frequencies and, consequently, experience evolution. MIGRATION (GENE FLOW) Population 1 Population 2 #3

34. Conditions that must occur for Natural Selection 1. VARIATION OF A TRAIT IN A POPULATION 2. The trait must be inheritable The tiniest dog in a litter has reduced differential reproductive success. Its more robust siblings prevent access to the food it needs to grow and thrive. 3. One version of the trait must provide an advantage over a different version of the trait. Mechanism of Evolution Natural Selection #4