* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download HERE
Survey
Document related concepts
Sociobiology wikipedia , lookup
On the Origin of Species wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Sexual selection wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Organisms at high altitude wikipedia , lookup
Theistic evolution wikipedia , lookup
Evidence of common descent wikipedia , lookup
Natural selection wikipedia , lookup
Inclusive fitness wikipedia , lookup
Population genetics wikipedia , lookup
Saltation (biology) wikipedia , lookup
The Descent of Man, and Selection in Relation to Sex wikipedia , lookup
Transcript
Evolution Review Chapters 21, 22, & 23 Ch. 21 Genes within Populations #2 5 Mechanisms of evolutionary change 1. Natural selection traits that improve survival or reproduction will accumulate in the population adaptive change 2. Genetic drift frequency of traits can change in a population due to random chance events random change More pronounced in small populations #2 and #9: Genetic Drift Chance events changing frequency of traits in a population not adaptation to environmental conditions not selection founder effect small group splinters off & starts a new colony it’s random who joins the group bottleneck a disaster reduces population to small number & then population recovers & expands again but from a limited gene pool who survives disaster may be random Founder effect When a new population is started by only a small group of individuals just by chance some rare alleles may be at high frequency; others may be missing skew the gene pool of new population human populations that started from small group of colonists example: colonization of New World Don’t fence me in! albino deer Seneca Army Depot Out of Africa Likely migration paths of humans out of Africa Many patterns of human traits reflect this migration Bottleneck effect When large population is drastically reduced by a disaster famine, natural disaster, loss of habitat… loss of variation by chance event alleles lost from gene pool not due to fitness narrows the gene pool Cheetahs All cheetahs share a small number of alleles less than 1% diversity as if all cheetahs are identical twins 2 bottlenecks 10,000 years ago Ice Age last 100 years poaching & loss of habitat Peregrine Falcon Conservation issues Bottlenecking is an important concept in conservation biology of endangered species loss of alleles from gene pool reduces variation reduces adaptability Breeding programs must consciously outcross Golden Lion Tamarin 5 Agents of evolutionary change Mutation Gene Flow Genetic Drift Non-random mating Selection #3: Variation & natural selection Variation is the raw material for natural selection there have to be differences within population some individuals must be more fit than others Ch. 22 Evidence for Evolution LaMarck (1744-1829) Organisms adapted to their environments by acquiring traits change in their life time Disuse organisms lost parts because they did not use them — like the missing eyes & digestive system of the tapeworm Perfection with Use & Need the constant use of an organ leads that organ to increase in size — like the muscles of a blacksmith or the large ears of a night-flying bat transmit acquired characteristics to next generation Then along comes Darwin… Charles Darwin 1809-1882 British naturalist Proposed the idea of Galapagos evolution by natural Islands selection Collected clear evidence to support his ideas 1831-1836 22 years old! But Darwin found… a lot of finches Darwin was amazed to find out: All 14 species of birds were finches… But there is only one Large Ground species of finch on theFinch? Finch mainland! Small Ground Sparrow? Finch How did one species of finches become so many different species now? Warbler Finch Woodpecker? Veg. Tree Finch Warbler? Correlation of species to food source Seed eaters Flower eaters Insect eaters Rapid speciation: new species filling new niche because they inherited successful adaptations. Adaptive radiation Darwin’s finches Differences in beaks allowed some finches to… successfully compete successfully feed successfully reproduce pass successful traits onto their offspring More observations… Correlation of species to food source Whoa, Turtles, too! Many islands also show distinct local variations in tortoise morphology… …perhaps these are the first steps in the splitting of one species into several? More observations… Glyptodont fossils Sloth fossils Modern sloth Modern armadillos Why should extinct species & living species be found on the same continent? Essence of Darwin’s ideas Evolution by Means of Natural Selection 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 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 What are the 4 lines of evidence that support Darwin’s ideas?… Human Macaque Dog Bird 8 32 45 Frog Lamprey 67 125 0 10 20 30 40 50 60 70 80 90 100 110 120 1. What are the lines of evidence that support Darwin’s ideas? Fossil record 550 500 Body size (kg) 450 Equus 400 350 300 250 Merychippus 200 150 Mesohippus Hyracotherium 100 50 Nannippus 60 55 50 45 40 35 30 25 20 15 10 Millions of years ago 5 0 2. What are the lines of evidence that support Darwin’s ideas? Terminal bud Lateral buds Cabbage Brussels sprouts Artificial selection Leaves Flower cluster Kale Cauliflower Broccoli Stem Flower and stems Wild mustard Kohlrabi 3. What are the lines of evidence that support Darwin’s ideas? Anatomical evidence Homologous structures Similar structure Similar development Different functions Evidence of close evolutionary relationship recent common ancestor Analogous structures Convergent Don’t be fooled by their looks! evolution Those fins & tails Does this mean & sleek are they havebodies a recent common ancestor? analogous structures! Solving a similar problem with a similar solution Vestigial organs These are Why would whales remnants of have pelvis & leg bones structures that were if they were always functional in sea creatures? ancestral species 4. What are the lines of evidence that support Darwin’s ideas? Molecular record Comparing DNA & protein structure universal genetic code! DNA & RNA compare common genes cytochrome C (respiration) hemoglobin (gas exchange) Human/kangaroo Closely related species have sequences that are more similar than distantly related species DNA & proteins are a molecular record of evolutionary relationships Nucleotide substitutions 100 Dog/ cow 75 Human/ cow Rabbit/ rodent 50 Horse/ donkey Llama/ cow Horse/cow Sheep/ goat 25 Human/rodent Pig/ cow Goat/cow 0 0 25 50 75 100 Millions of years ago 125 Human Macaque Dog Bird Frog Lamprey The sequence in DNA & proteins Why compare is a molecular DNA & proteins record of evolutionary across species? relationships. Comparative hemoglobin structure 8 32 45 67 125 Why compare these genes? 0 10 20 30 40 50 60 70 80 90 100 110 120 Number of amino acid differences between compare common genes hemoglobin (146 aa) of vertebrate species and that of humans C (respiration) cytochrome hemoglobin (gas exchange) 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 Parallel/convergent evolution Niche Burrower Placental Mammals Mole Convergent evolution of analogous Marsupial mole burrowing characteristics Australian Marsupials Anteater Anteater Nocturnal insectivore Mouse Climber Numbat Marsupial mouse Spotted cuscus Lemur Glider Stalking predator Chasing predator Sugar glider Flying squirrel Ocelot Tasmanian cat Wolf Tasmanian “wolf” Coevolution Two or more species reciprocally affect each other’s evolution predator-prey disease & host competitive species mutualism pollinators & flowers #7. Types of Natural Selection Selection acts on any trait that affects survival or reproduction predation selection physiological selection sexual selection #8. Effects of Selection Changes in the average trait of a population DIRECTIONAL SELECTION STABILIZING SELECTION DISRUPTIVE SELECTION speciation? giraffe neck horse size human birth weight rock pocket mice