Chapter 15 1/30/2015. Learning Objectives. Voyage of the HMS Beagle. Charles Darwin

Transcription

1 Student Learning Goals & Achievement Scale - Biology SC.912.L.15.1, 13, 14 Evolution Learning Objectives Goal: Describe how the scientific theory of evolution is an agent of change of life on Earth. 4 -Explore through writing how the scientific theory of evolution acts as an agent of change of life on Earth. 3 - Describe how the scientific theory of evolution is an agent of change. 2 Summarize factors that support the scientific theory of evolution. 1 Define natural selection, genetic drift, gene flow as they relate to evolution. 1. Define the biological process of evolution. 2. Summarize the history of scientific ideas about evolution. 3. Descr ibe Charles Da rwin s contributions to scientific thinking about evolution. 4. A n alyze the r easoning in Da rwin s theory of ev olution by natural selection 5. Rela te the concepts of a daptation and fitness to the theory of natural selection 6. Rela te sev eral inferences a bout the history of life that are supported by evidence from fossils and rocks. 7. Ex plain how biogeography provides ev idence that species ev olve adaptations to their environments. 8. Ex plain how the anatomy and development of organisms pr ov ide evidence of sh ared ancestry. 9. Compare the use of biological molecules with other types of analysis of evolutionary relationships. 10. Describe the ongoing development of evolutionary theory. 11. Describe how convergent evolution can result among different species. 12. Explain how divergent evolution can lead to species diversity 13. Compare artificial selection and natural selection 14. Explain how organisms can undergo coevolution Chapter 15 THEORY OF EVOLUTION Charles Darwin Voyage of the HMS Beagle English naturalist Descent with medication 5 years on HMS Beagle Proposed NS as a mechanism for evolution Married 1 st cousin Emma Wedgewood Book- On the Origin of Species 1

2 Mechanisms of Evolution Galápagos Islands Natural Selection Darwin Variation is genetic In heritance of Acquired Ch aracteristics Jean-Baptiste Lamarck Variation by experience Selection Artificial Selection A rtificial Selection Breeder chooses desired characteristics Agriculture/Livestock- Early on Natural Selection En v ironment determines w h ich individual produces th e most offspring 3 con ditions for NS to occur Var iation must exist among individuals in a population Var iation among individuals must r esult in differences in the number of offspring sur viving Var iation must be genetically i nherited Fruit fly lab experiments Selected fruit flies with lots of bristles on abdomen Chose only those with the most bristles to reproduce 86 generations later: average number of bristles had quadrupled Body size, eye color, growth rate, life span, & exploratory behavior Artificial Selection-Example Artificial Selection Important in Agriculture Modification of crops and livestock Oil contents of corn from1896 (4.5%) to 1986 (450%) Very different now compared to ancestor 2

3 Domesticated breeds from artificial selection 4 main parts of Darwin s reasoning Breeds of dogs Cats, pigeons, silver fox 1. Overproduction 2. Genetic variation 3. Struggle to survive 4. Differential Reproduction NS consists of these 4 components Organisms have variations Individuals have heritable variations More individuals produced each generation than environment can support Some individuals have adaptive characteristics Enables increased survival and reproduction In creasing proportion of succeeding generations will have these characteristics Populations become adapted to their local environment through change in individuals Darwin emphasized that individuals from a population vary in their: Fu nctional characteristics Phy sical characteristics Beh avioral characteristics Proposed that these variations: Are essential Allow adaptation to the environment over time Fitness and Its Measurement Fitness: A phenotype with greater fitness usually increases in frequency Most fit is given a value of 1 Fitness is a combination of: Survival: how long does an organism live Mating success: how often it mates Number of offspring per mating that survive To a v oid predators 3 examples of NS To m atch climatic conditions Lactate dehydrogenase in Fundulus heteroclitus (mummichog fish) varies with latitude For pesticide resistance Mu tation in Norway rats that doesn t allow wafarin to bind to site (rat poison resistant rats?) 3

4 The beaks of Darwin s Finches Darwin s selection hypothesis Darwin collected 31 species of finches from the Galapagos Islands Probably wrens, grosbeaks, and blackbirds Joh n Gould-ornithologist identified the birds were related species, differences in their bills The differences among species in beak size and shape hav e evolved as the species adapted to use different food resources Theory of evolution by natural selection requires 3 criteria Variation must exist in the population Th e variation must lead to differences among individuals in lifetime reproductive success V ariation among individuals must be genetically transmitted to the next generation Testing Darwin s proposal of evolution by natural selection More than 130 years later Peter and Rosemary Grant & students (Princeton University) begin studying the medium ground finch (Geospiza fortis) Da phne Major-Galapagos Islands Discovered the bird feeds on Small tender seeds that are produced in abundance during th e rainy season Feeds on larger, drier seeds during droughts Measured beak depth every year Beak depth changed every year Had caught evolution in action Grant & Grant Work To ensure that the changes in beak depth was not reflecting a response to diet Mea sured the relation of parent beak size to offspring beak size Discovered depth of beak size was same for parent/offspring Natural selection selects for beak size in response to the available food supply (Oscillating selection) Peppered moths and industrial melanism Distinct coloration of moths Variety of adult shades from light gray with black peppered spots to jet black (melanistic) Different alleles of a single gene code for color Black is dominant, but rare before 1850 Increase in frequency of black moths near industrialized cities. Became close to 100% of population Tree trunks in this area, black by soot of pollution and lightcolored lichens were killed 4

5 1.) Fossil evidence Fossil Evidence Fossils- the preserved remains of once-living organisms Amber, Siberian permafrost, dry caves, rocks Rock fossils are created when three events occur organism buried in sediment calcium in bone or other hard tissue mineralizes surrounding sediment hardens to form rock Fossils document ev olutionary transition Th e oldest known bird fossil is the Archaeopteryx It is in termediate between bir d and dinosaur Possesses some ancestral tr aits and some traits of pr esent day birds Archaeopteryx was first found in ) Convergent evolution and the biogeographical record Convergent Evolution Biogeography is the study of the geographic distribution of species Conv ergent evolution is the process that organisms that are not closely related indepedently evolve similar traits as a result of having to adapt to similar env ironments. Example: Marsupials and placentals Hu mmingbirds and sunbirds Convergent evolution is a widespread phenomenon Fast moving marine predators Stream-line body to minimize friction h ttp://dsc.discovery.com/v ideos/perfect-predators-shortsm ako-shark-speed.html Island trees Elsewhere are shrubs or small bushes in the sunflower family Why? Seeds from trees rarely make it to islands and the species that make it to islands fill the empty niche 3.) Anatomical Evidence for Evolution Hom ology of the bones of the forelim b of mammals Hom ologous have same ev olutionary origin, but have different structure and function Analogous have similar structure and function, but different ev olutionary origin 5

6 Early embryonic development shows similarities in some groups Comparing the eyes of vertebrates to mollusks Many vertebrates display similarities early on, but become different as they develop Early vertebrate embryos possess pharyngeal pouches that develop into: In humans: glands and ducts In fish: gill slits V ertebrate Eye Mollusk Eye Some structures are imperfectly suited to their use Vestigial structures- holdovers from the past Neck vertebrae Most organisms with long necks have increased neck vertebrae for flexibility Geese- 25 Plesioasaurs- 76 Most mammals- only 7 Even giraffes Because of the absence of variation in vertebrae # Selection led to an evolutionary increase in vertebra size to produce the long neck of the giraffe Vestigial structures: have no apparent function, resemble structures their ancestors possessed Examples: What other vestigial structures can you think of in humans? 4.) Biochemical Evidence Coevolution Almost all living organisms: Use the same basic biochemical molecules Utilize same DNA triplet code Utilize same 20 amino acids in their proteins When two or more species have evolved adaptations to each other s influence Example: Plants have evolved so that specific animals pollinate them. DNA base-sequence differences: When very similar, suggest recent common descent When more different, suggest more ancient common descent 6

7 Darwin s conclusions Islands are often missing plants and animals common on continents Species present on islands often diverged from continental relatives Island species usually are more closely related to species on nearby continents Species arrive on islands by dispersing across the water Dispersal from nearby areas is more likely than distant sources Species that can fly, float or swim can inhabit islands Colonizers often ev olve into many species 7