Evidence of Evolution by Natural Selection (Ch. 16.4) Dodo bird
Evidence supporting evolution Fossil record Anatomical record Molecular record Artificial selection
Fossil record Layers of sedimentary rock contain fossils new layers cover older ones, creating a record over time Show that a succession of organisms have populated Earth throughout a long period of time
Formation of sedimentary strata containing fossils 1 Rivers carry sediment to the ocean. Sedimentary rock layers containing fossils form on the ocean floor. 2 Over time, new strata are deposited, containing fossils from each time period. 3 As sea levels change and the seafloor is pushed upward, sedimentary rocks are exposed. Erosion reveals strata and fossils. Younger stratum with more recent fossils Older stratum with older fossils
A gallery of fossil types (c) Leaf fossil, about 40 million years old (b) Petrified tree in Arizona, about 190 million years old (a) Dinosaur bones being excavated from sandstone (d) Casts of ammonites, about 375 million years old (f) Insects preserved whole in amber (g) Tusks of a 23,000-year-old mammoth, frozen whole in Siberian ice (e) Boy standing in a 150-million-year-old dinosaur track in Colorado
Support (proof?) for a VERY old Earth.
A dragonfly fossil from Brazil, more than 100 million years old
The Geologic Record
Body size (kg) Evolutionary change in horses 550 500 450 400 350 300 250 200 150 100 50 Mesohippus Hyracotherium Merychippus Equus Nannippus 60 55 50 45 40 35 30 25 20 15 10 5 0 Millions of years ago
Evolution of birds Archaeopteryx lived about 150 mya links reptiles & birds Smithsonian Museum, Washington, DC
Whales, you ask... Land Mammal????
A transitional fossil linking past and present
2006 Fossil Discovery of Early Tetrapod Tiktaalik missing link from sea to land animals
Anatomical record Homologous structures similarities in characteristics resulting from common ancestry
Homologous structures Similar structure Similar development Different functions Evidence of close evolutionary relationship recent common ancestor
Homologous colored leaves structures spines leaves succulent leaves needles tendrils
Analogous structures Separate evolution of structures similar functions similar external form different internal structure & development different origin no evolutionary relationship Don t be fooled by their looks! Solving a similar problem with a similar solution
Convergent evolution Flight evolved in 3 separate animal groups analogous structures Does this mean they have a recent common ancestor?
Convergent evolution of analogous burrowing characteristics
Convergent evolution Fish: aquatic vertebrates Dolphins: aquatic mammals similar adaptations to life in the sea not closely related Those fins & tails & sleek bodies are analogous structures!
Parallel Evolution Convergent evolution in common niches Similar ecological roles in similar environments, Similar adaptations were selected but are not closely related marsupial mammals placental mammals
Parallel types across continents Niche Placental Mammals Australian Marsupials Burrower Mole Marsupial mole Anteater Nocturnal insectivore Anteater Mouse Numbat Marsupial mouse Climber Glider Stalking predator Lemur Flying squirrel Ocelot Spotted cuscus Sugar glider Tasmanian cat Chasing predator Wolf Tasmanian wolf
Vestigial organs Structures that serve little or no function remnants of structures that were functional in ancestral species deleterious mutations accumulate in genes for non-critical structures without reducing fitness snakes & whales remains of pelvis & leg bones of walking ancestors eyes on blind cave fish human tail bone This is not LaMarck s loss from disuse!
Vestigial organs Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures?
Comparative embryology Similar embryological development in closely related species all vertebrate embryos have similar structures at different stages of development gill pouch in fish, frog, snake, birds, human, etc.
Anatomical similarities in vertebrate embryos Pharyngeal pouches Post-anal tail Chick embryo Human embryo
Nucleotide substitutions Molecular record Comparing DNA & protein structure universal genetic code! DNA & RNA compare common genes cytochrome C (respiration) hemoglobin (gas exchange) Closely related species have sequences that are more similar than distantly related species A molecular record of evolutionary relationships 100 75 50 25 Horse/ donkey Sheep/ goat Llama/ cow Goat/cow Why compare these genes? Rabbit/ rodent Pig/ cow Dog/ cow Horse/cow 0 0 25 50 75 100 125 Millions of years ago Human/kangaroo Human/ cow Human/rodent
Comparison of a protein found in diverse vertebrates Species Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide Human 100% Rhesus monkey 95% Mouse 87% Chicken 69% Frog 54% Lamprey 14%
Comparative hemoglobin structure Human Macaque Dog Bird Frog Lamprey Why does comparing amino acid sequence measure evolutionary relationships? 8 32 45 67 125 0 10 20 30 40 50 60 70 80 90 100 110 120 Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans
Building family trees Closely related species (branches) share same line of descent until their divergence from a common ancestor
Artificial selection Artificial breeding can use variations in populations to create vastly different breeds & varieties descendants of wild mustard descendants of the wolf
Natural selection in action Insecticide & drug resistance insecticide doesn t kill all individuals resistant survivors reproduce resistance is inherited insecticide becomes less & less effective
Evolution of drug resistance in HIV Patient No. 1 Patient No. 2 Patient No. 3 Weeks
Evolution Misconceptions
if we came from apes how come were not hairy and have a big mouth and did we end up looking like we do know and besides there isnt any serious proof of apes they showd a video saying an ape waswondering around in the forest that thing looked exactly like a costume that i had saw at a store know one ever cought an ape -From a post on the Internet NOT THIS KIND!!! (beyond help)
The Complexity Fallacy
Evolution is not goal-oriented An evolutionary trend does not mean that evolution is goal-oriented. Surviving species do not represent the peak of perfection. There is compromise & random chance involved as well Remember that for humans as well! Evolution is not the survival of the fittest. Rather it is the survival of the just good enough.
Unintelligent Design Serial circulation in the mammalian heart
"Nothing in biology makes sense except in the light of evolution." -- Theodosius Dobzhansky March 1973 Geneticist, Columbia University (1900-1975)
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 (1904-2005)
I might be dead, but Perhaps you children would appreciate a bit of what you call the rap music?!?
Don t Be Unintelligent... Ask Questions!!
Evidence of Evolution by Natural Selection Testable Hypotheses
Just Because Things Seem Obvious Doesn t Mean They Don t Need To Be Supported
Peppered Moths Dark vs. light variants Year % dark % light 1848 5 95 1895 98 2 1995 19 81
Peppered moth What was the selection factor? early 1800s = pre-industrial England low pollution lichen growing on trees = light colored bark late 1800s = industrial England factories = soot coated trees killed lichen = dark colored bark mid 1900s = pollution controls clean air laws return of lichen = light colored bark industrial melanism
Genome sequencing What can whole genome sequence data tell us about evolution of humans?
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?
Chromosomal fusion Testable prediction: If common ancestor had 48 chromosomes (24 pairs), then humans carry a fused chromosome (23 pairs). Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo) 48 gorilla (Gorilla) 48 chimpanzee (Pan) 48 Testable! This is what makes evolution science & not belief! human (Homo) 46 Ancestral Chromosomes Fusion Homo sapiens Centromere Telomere Inactivated centromere Telomere sequences
Hillier et al (2005) Generation and Annotation of the DNA sequences of human chromosomes 2 and 4, Nature 434: 724 731. Test of the Human Genome Ancestral Chromosomes Fusion Homo sapiens Chr 2 Inactivated centromere Telomere sequences 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
Geographic variation in chromosomal mutations 1 2.4 3.14 5.18 6 7.15 8.11 9.12 10.16 13.17 19 XX 1 2.19 3.8 4.16 5.14 6.7 9.10 11.12 13.17 15.18 XX
Any Questions?? 2007-2008
Review Questions
1. A complete fossil record 1. Exists because of the great preservation in ocean sediment 2. Exists because of the solidification of minerals around organisms 3. Is available because of the small location in which all organisms used to live 4. Exists because organisms that die become embedded in the soil to form rocks 5. Does not exist.
2. The similarity of insect wings and bird wings is an example of A. Behavioral adaptations B. Geographic isolation C. Adaptive radiation D. Convergent evolution E. Divergent evolution
3. The human appendix is an example of 1. A balanced polymorphism 2. Divergent evolution 3. Convergent evolution 4. A vestigial structure 5. A homologous structure
4. One piece of evidence that supports evolution from molecular biology is: 1. Carbohydrate structure 2. Amino acid sequences 3. Lipid composition 4. Nucleotide structure 5. Cellulose chains