1. Some of the slides (35-45) we didn’t go over during the last class will be part of today’s lecture.

2. Ch. 17 Microevolution The smallest unit that evolves is a population: – all the members of a single species living in a defined geographical area at a given time.

3. original coloration (a) Original environment (b) Altered environment lighter coloration expanse of barren terrain darker coloration population A population B Figure 17.1

4. Genetic Basis of Evolution Genes exist in variant forms called alleles – Different versions of the same gene – Usually an individual only has 2 different alleles of the same gene One from bio mom, one from bio dad

5. Genetic Basis of Evolution A population, however, is likely to possess many alleles for a given gene. – gene pool: The sum total of alleles in a population The basis of evolution is a change in the frequency of alleles in a gene pool.

6. Alternative Versions: Real Life Example Underwear

8. 17.2 Evolution as a Change in the Frequency of Alleles

9. Figure 17.2 maternal chromosome 3 paternal chromosome 3 maternal chromosome 3 paternal chromosome 3 alleles dark coloration light coloration a1a1 a2a2 a2a2 a4a4

10. Genetic Basis of Evolution With such a change, a population can be said to have evolved. Evolution at this level is referred to as microevolution: a change of allele frequencies within a population over a relatively short period of time.

11. Genetic Basis of Evolution Conversely, macroevolution, a product of microevolution, is evolution on a larger scale. Macroevolution is evolution that results in the formation of new species or other large groupings of living things.

13. 17.3 Five Agents of Microevolution Five evolutionary forces can result in changes in allele frequencies within a population. These agents of microevolution are: 1.mutation 2.gene flow 3.genetic drift 4.sexual selection 5.natural selection

14. Agents of Change: Five Forces That Can Bring about Change in Allele Frequencies in a Population Agent Description Mutation Gene flow Genetic drift Sexual selection Natural selection Alteration in an organism’s DNA; generally has no effect or a harmful effect. But beneficial or “adaptive” mutations are indispensable to evolution. The movement of alleles from one population to another. Occurs when individuals move between populations or when one population of a species joins another, assuming the second population has different allele frequencies than the first. Chance alteration of gene frequencies in a population. Most strongly affects small populations. Can occur when populations are reduced to small numbers (the bottleneck effect) or when a few individuals from a population migrate to a new, isolated location and start a new population (the founder effect). Occurs when some members of a population mate more often than other members. Some individuals will be more successful than others in surviving and hence reproducing, owing to traits that give them a better “fit” with their environment. The alleles of those who reproduce more will increase in frequency in a population. Table 17.1

15. 1. Mutations Figure 17.3 Normal Point mutation incorrect nucleotide sequence correct nucleotide sequence Normal Deletion complete chromosome 5 incomplete chromosome 5 (a) (b) Any permanent alteration in an organism’s DNA Some are heritable - they can be passed on from one generation to the next

16. Mutations Happens fairly infrequently – most mutations either have no effect or are harmful Adaptive mutations – Vital to evolution – The only way entirely new genetic information comes along

17. 2. Gene Flow The movement of genes from one population to another. Takes place through migration – the movement of individuals from one population into the territory of another

18. Figure 17.4 (a) Hawaiian silversword(b) Tarweeds in California North America Hawaiian Islands Pacific Ocean gene flow How did plant life come about in Hawaii?

19. Genetic Drift A random change in allele frequency Not related to reproductive success

20. Genetic Drift Figure 17.5

21. Genetic Drift Genetic drift can have large effects on small populations through two common scenarios: – the Bottleneck Effect – the Founder Effect

22. 4. Sexual Selection – the guys with more game get more ladies A form of natural selection that can affect the frequency of alleles in a gene pool Occurs when differences in reproductive success arise because of differential success in mating – Mate more, pass more genes along

23. Sexual Selection Figure 17.7 If you got more game than the other guys, you pass along more of your genes This will increase the frequency of your alleles the next generation of the population

24. 5. Natural Selection Most powerful force In a population, if you are more likely to survive, you are more likely to reproduce and pass on traits that allowed you to survive

25. © 2011 Pearson Education, Inc. Ch. 18 The Outcomes of Evolution – Macroevolution

26. 18.1 What is a species?

27. Biological Species Concept  Species: different kinds of organisms  Species are natural populations of organisms that: Interbreed with each other or could possibly interbreed in a natural environment Cannot interbreed with organisms outside their own group (reproductive isolation)

28. What Is a Species? Definition does not fit all – Only sexually reproducing organisms Bacteria & archaea -reproduce through simple cell division

29. 18.2 How Do New Species Arise? Allopatric Speciation Sympatric Speciation

30. 18.4 The Categorization of Earth’s Living Things

31. How do we name species? We need an organizational system! Carolus Linnaeus…

32. Carolus Linnaeus and Binomial Nomenclature A scientific name consists of two parts: 1. Genus 2. Species Horse: Equus ferus Zebra: Equus quagga

33. Taxonomy More than just two names… 8 major categories (from least to most inclusive) – species, genus, family, order, class, phylum, kingdom, and domain

34. Linnaean System of Classification

35. Domain Kingdom Phylum Class Order Genus You should know the order Species Did King Phillip Come Over For Good Sex? Family

36. Figure 18.10 Linnaean System of Classification Kingdom (Animalia) Phylum (Chordata) Class (Mammalia) Order (Carnivora) Family (Felidae) Genus (Felis) Species (Felis domestica)

37. Present dogsraccoons bears sea lions seals walrusweasels 10 30 20 40 50 60 ancestral carnivores Millions of years ago Figure 18.11 Family Tree of Mammalian Carnivores

38. Systematics A type of biology that looks at how closely organisms are related – Think family tree You are more closely related if you share a mom than if you just share a grandma Evolutionary family trees = “phylogenies” – Various evidence radiometric dating, the fossil record, DNA sequence comparisons

39. 18.5 Classical Taxonomy and Cladistics In determining phylogeny, classical taxonomy establishes evolutionary relationships Classical taxonomy is subjective Cladistics – a firm rule for inferring relatedness – It counts the shared derived characters two organisms have – Establishes lines of descent

40. hagfish lizard deer lion seal aquatic habitat carnivorous feeding mammary glands tetrapod structure Derived characters A Simple Cladogram Figure 18.13

41. (a) Classical view of relationships among tetrapods (b) Cladistic view of relationships among tetrapods Reptilia Aves Mammalia turtles snakes lizards crocodiles dinosaurs birds mammals turtles snakeslizards crocodiles dinosaurs birds Classical Taxonomy and Cladistics Figure 18.14

42. Activity Everyone will turn in their own paper You may work in small groups