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vegetative propagation Produce many individuals at one time Individuals can survive present environmental but may not survive changes Evolution Biological Evolution: analyzes how heritable traits change in frequency within a population over time Physical traits (variations) Molecular sequences (mutations, DNA) Behavioural traits (reproduction, courtship) Microevolution: evolution on a single population over a short period of time Macroevolution: when small changes accumulate over a long period of time producing noticeable changes in species Darwin Charles Darwin Evolution: or change over time, is the process by which modern organisms have descended from ancient organisms. Wrote Origin of the Species Observed organisms on the Galapagos Islands Darwin's Finches ● O The finches on the different islands were similar to finches found on the mainland but they adapted to the food sources on the individual islands Bird Beaks and Food Sources Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cactus ground finch Large ground finch (seeds) (cactus fruits and flowers) Vegetarian finch (buds) Woodpecker finch (insects) Evidence Field of Anatomy Field of Embryology Field of Biochemistry Field of Paleontology Anatomy The study of the structures of organisms Organisms that have diverged from a common ancestor often have homologous structures (similar characteristics resulting from common ancestry). The greater the numbers of shared homologous structures between 2 species, the more closely the species are related. Many species have vestigial organs (structures with little or no important functions to the organism) that are remnants of structures that had important functions in ancestors of the species. Species living in different location sunder similar ecological conditions may evolve similar structures, called analogous structures, are not evidence of evolution because they do not result from shared ancestry. (features of different species that are similar in function but not necessarily in structure) Analogous Structures (Streamline Appendages) Dolphin (mammal) Shark (fish) Fin Penguin (bird) Wing Analogous EX: Butterfly and Bird Wings Flipper Homologous Structures (Pentadactyl Limbs) [}(6 Human Cat Whale Bat human sheep bat seal Homologous Structures ex. arm of human wing of bat flipper of seal front leg of sheep Figure 15.8 Vestigial structures, such as pelvic bones in the baleen whale, are evidence of evolu tion because they show struc- tural change over time. Vestigial Structures • remnants of pelvis and hind limbs in snakes hind legs in whales • wings on many flightless birds • erector pili (goose bumps) • body hair • human tailbone • wisdom teeth ● male breast tissue and nipples appendix in humans Embryology The study of the embryonic development of organisms Provides another type of data for the support of evolution by comparing the anatomies of embryos of organism development Similarities in patterns of development or structures that are not obvious in adult organisms become evident when embryonic development is observed Embryos of vertebrates are very similar in appearance early in development but may grow into different structures in the adult form Similar structures of these embryos may suggest that these species evolved from common ancestors to do to do do 00000000 093505 Maleatharla 2900 Fash Salamander Tonok Chick Car Rabb Human THE VERTEBRATE BODY YLOGENY AHd FERTILIZED EGG. HUMAN LATE CLEAVAGE BODY SEGMENTS. LIMB BUD STAGE MONKEY PIG CHICKEN SALAMANDER € 6 B ADULT / OFFSPRING LARVA/PETUS. 3 & F ONTOGENY Biochemistry • The study of the chemical processes in organisms (studies genes and proteins to provide support for biological evolution) The more similar the DNA and amino acid sequences in proteins of two species, the more likely they are to have diverged from a common ancestor Biochemistry provides evidence of evolutionary relationships among species when anatomical structures may be hard to use. Ex: When species are so closely related that they do not appear to be different When species are so diverse that they share few similar sturctures Human Base pairs Fruit Fly Adenine Thymine Guanine Cytosine Organism Amino Acid Sequence Chimpanzee Serine-Valine-Leucine-Stop Serine-Valine-Proline-Stop Serine-Lysine-Valine-Stop Sugar phosphate backbone oooo Amino Acids Primary protein structure is sequence of a chain of amino acids Paleontology How are fossils made? some animals are quickly buried after their death - over time, more sediment covers the remains - The study of prehistoric life The fossil record provides evidence of life forms and environments along a timeline and supports evolutionary relationships by showing the similarities between current species and ancient species The fossil record is not complete because most organisms do not form fossils. Many of the gaps in the fossil record have been filled in as more fossils have been discovered O The older the fossils, the less resemblance there is to modern species - the parts that don't rot become replaced with minerals this results in a heavy, rock-like copy of the original object (fossil) **most animals do not become fossils - they just decay! Pedernes Tulernation Acanthosts Second Oldest rock layers are deposited from the bottom up... 1 2 3 Youngest Layer Oldest Layer Mechanisms of Evolution Natural Selection Organisms that have traits that are well suited to the environment will have a better chance of of survival (fitness), while those with less desirable traits may struggle to survive Allows for the most favorable phenotypes to survive and be passed onto future generations Non-random Mating Not random mating (mating is specific) Limits the frequency of the expression of certain alleles Parents look for the best possible mate (ideal traits) to produce offspring with these traits Genetic Drift Random change in the frequency of alleles of a population over time. Due to chance, rare alleles in a population will decrease in frequency and become eliminated; other alleles will increase in frequency and become fixed. Mutations Changes in an organism's DNA (can be harmful, beneficial, or silent) Increases the frequencies and types of alleles within a population Gene Flow The movement of genes into or out of a population (immigration and emigration) Natural Selection • Organisms with favorable traits (more frequency) will survive in an ecosystem and those with non-favorable traits will reproduce less, therefore the phenotype will be seen less (less frequency) If the ecosystem changes organisms that have the most favorable traits will be seen more. Natural Selection Example X A population of mice has moved into a new area where the rocks are very dark. Due to natural genetic variation, some mice are black, while others are tan. Some mice are eaten by birds Mice reproduce, giving next generation Tan mice are more visible to predatory birds than black mice. Thus, tan mice are eaten at higher frequency than black mice. Only the surviving mice reach reproductive age and leave offspring. Because black mice had a higher chance of leaving offspring than tan mice, the next generation contains a higher fraction of black mice than the previous generation. The tan mice in picture 1 are easily seen by the bird, therefore that phenotype is non-favorable. The black phenotype can blend into the environment, therefore it is a favorable trait and we will see this phenotype more. As ecosystems change, different phenotypes can become more or less favorable. Natural Selection Snail with black shell Snail with grey shell selection pressure Natural Selection Snail with white shell Non-Random Mating random mating Nonrandom mating Random mating Genetic Drift GENETIC DRIFT CHANGE IN ALLELE FREQUENCY DUE TO A CHANCE EVENT SWAT! RATIO 5:5 RATIO 5:51 RATIO 10:2 REPRODUCTION Genetic drift Random disappearance of genotypes in the population (eg, due to death, lack of reproduction) Surviving population has decreased genetic diversity Surviving population reproduces and increases in number but still has less genetic diversity Mutations Mutation Antenna Head- Antenna Head- Eye Eye Thorax Legs Thprax Legs Wings Wings Abdomen Wildtype Abdomen Mutant Gene Flow a B Aa AA AA Aa emigration aa Population I aa aa aa (aa aa aa aa (AA) (AA) Gene flow is the exchange of genes between two populations. Buzzle.com immigration (AA) AA AA (AA) AA Population II