Evidence for Evolution by Natural Selection. Raven Chapters 1 & 22

Transcription

1 Evidence for Evolution by Natural Selection Raven Chapters 1 &

2 Science happens within a culture What was the doctrine of the time? TINTORETTO The Creation of the Animals 1550

3 Then along comes Darwin years old!

4 Then along comes Darwin Descendant species & those dang finches! Ancestral species Woodpecker finch Small insectivorous tree finch Warbler finch Cactus finch Sharp-beaked finch Small ground finch Large insectivorous tree finch Vegetarian AP tree Biology finch Insect eaters Bud eater Cactus eater Seed eaters Medium ground finch Large ground finch

5 Darwin s finches Differences in beaks allowed some finches to successfully compete successfully feed successfully reproduce pass successful traits onto their offspring

6 In historical context Other people s ideas paved the path for Darwin s thinking competition: struggle for survival population growth exceeds food supply land masses change over immeasurable time

7 Voyage: November 24, 1859, Darwin published On the Origin of Species by Means of Natural Selection

8 Correlation of species to food source Seed eaters Flower eaters Insect eaters Rapid speciation: new species filling niches, because they inherited successful adaptations. Adaptive radiation

9 Beak variation in Galapagos finches (a) Cactus eater. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. (c) Seed eater. The large ground finch (Geospiza magnirostris) has a large beak adapted for cracking seeds that fall from plants to the ground. (b) Insect eater. The green warbler finch (Certhidea olivacea) uses its narrow, pointed beak to grasp insects.

10 Glyptodont fossils Modern armadillos Sloth fossils Modern sloth Why should extinct species & living species be found on the same continent?

11 Essence of Darwin s ideas Natural selection heritable variation exists in populations over-production of offspring more offspring than the environment can support competition for food, mates, nesting sites, escape predators differential survival successful traits = adaptations differential reproduction adaptations become more common in population

12 Where does Variation come from? Mutation random changes to DNA errors in mitosis & meiosis environmental damage Sexual reproduction mixing of alleles genetic recombination new arrangements of alleles in every offspring new combinations = new phenotypes

13 LaMarckian vs. Darwinian view LaMarck in reaching higher vegetation giraffes stretch their necks & transmits the acquired longer neck to offspring Darwin giraffes born with longer necks survive better & leave more offspring who inherit their long necks

14 Big Idea 1 The process of evolution drives the diversity and unity of life cells DNA

15 What are the 4 lines of evidence that support Darwin s ideas? Human Macaque DogBird Frog Lamprey

16 1. What are the lines of evidence that support Darwin s ideas? Fossil record Body size (kg) Mesohippus Hyracotherium Merychippus Equus 50 Nannippus Millions of years ago

17 Evolution of birds Archaeopteryx lived about 150 mya links reptiles & birds Smithsonian Museum, Washington, DC

18 Evolution of land animals 2006 Fossil Discovery of Early Tetrapod Tiktaalik missing link from sea to land animals from swimming (0 legs) to walking (4 legs)

19 Evolution of marine mammals But then, they actually found my fossil! Land Mammal???? At first, I was just a joke! Aquatic Mammal

20 2. What are the lines of evidence that support Darwin s ideas? Cabbage Artificial selection Terminal bud Lateral buds Brussels sprouts Flower cluster Leaves Kale Cauliflower Stem Flower and stems Broccoli Wild mustard Kohlrabi

21 Selective breeding the raw genetic material (variation) is hidden there

22 Natural selection in action Resistance NOT immunity! MRSA

23 3. What are the lines of evidence that support Darwin s ideas? Anatomical evidence

24 Homologous structures spines leaves succulent leaves Don t forget our plant friends! needles tendrils colored leaves

25 Analogous structures Convergent Don t be fooled by evolution their looks! Those tails Does fins this & mean & sleek they bodies have a are recent common ancestor? analogous structures! Solving a similar problem with a similar solution

26 Convergent evolution marsupial mammals These animals look very similar but does that mean they have a recent common ancestor? What is this evidence of? placental mammals

27 Parallel/convergent evolution Niche Placental Mammals Australian Marsupials Burrower Mole Convergent evolution of analogous Marsupial mole burrowing characteristics Anteater Anteater Numbat Nocturnal insectivore Mouse Marsupial mouse Climber Spotted cuscus Lemur Glider Flying squirrel Sugar glider Stalking predator Ocelot Tasmanian cat Chasing predator Wolf Tasmanian wolf

28 Vestigial organs These are Why would whales remnants of have pelvis & leg bones if they were always functional in sea creatures? structures that were ancestral species

29 4. What are the lines of evidence that support Darwin s ideas? Human Macaque Dog Bird Frog Lamprey The sequence in DNA Why & compare proteins DNA is a & molecular proteins record across of evolutionary species? relationships. Comparative hemoglobin structure Why compare these genes? Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans compare common genes cytochrome C (respiration) hemoglobin (gas exchange)

30 Building family trees

31 Genome sequencing What can data from whole genome sequencing tell us about evolution of humans?

32 Primate Common Ancestry? Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo) 48 gorilla (Gorilla) 48 chimpanzee (Pan) 48 human (Homo) 46 Hypothesis: Change in chromosome number? If these organisms share a common ancestor, then is there evidence in the genome for this change in chromosome number Could we have just lost a pair of chromosomes?

33 Chromosomal fusion Testable prediction: If common ancestor had 48 chromosomes (24 pairs), then humans carry a fused chromosome (23 pairs). What we should find: Ancestral Chromosomes Fusion Homo sapiens Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo) 48 gorilla (Gorilla) 48 chimpanzee (Pan) Testable! 48 human (Homo) 46 This is what makes evolution science & not belief! Inactivated centromere Telomere sequences in middle of chromosome Centromere: bonding point between chromosomes Telomere: at ends of chromosomes

34 Guess what we found?!? Ancestral Chromosomes Fusion Chromosome 2 in Homo sapiens Inactivated centromere Telomere sequences in middle of chromosome Hillier et al (2005) Generation and Annotation of the DNA sequences of human chromosomes 2 and 4, Nature 434: Chromosome 2 is unique to the human lineage of evolution, having emerged as a result of head-to-head fusion of two chromosomes that remained separate in other primates. The precise fusion site has been located in 2q13 2q14.1, where our analysis confirmed the presence of multiple subtelomeric duplications to chromosomes 1, 5, 8, 9, 10, 12, 19, 21 and 22. During the formation of human chromosome 2, one of the two centromeres became inactivated (2q21, which Well corresponds I ll to the centromere from chimp chromosome 13) and the be a monkey s centromeric structure quickly deterioriated. or an ape s uncle! Human Chromosome #2 shows the exact point at which this fusion took place

35 "Nothing in biology makes sense except in the light of evolution." -- Theodosius Dobzhansky March 1973 Geneticist, Columbia University ( )

36 Evolution is "so overwhelmingly established that it has become irrational to call it a theory." -- Ernst Mayr What Evolution Is 2001 Professor Emeritus, Evolutionary Biology Harvard University ( )

37 Don t be a Dodo Ask Questions!!