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Hypothesis An “If…then” statement or proposal of an outcome of an experiment. › (Ex. If I study, then I will pass the test.) Theory A hypothesis that has withstood extensive testing by a variety of methods, and a higher degree of certainty may be placed › (Ex. Theory of Evolution) Law Considered universal & invariable facts of the physical world › (Ex. Law of Gravity) Main idea: Multiple lines of evidence support the theory of evolution. Objectives: › Describe how fossils provide evidence of evolution. › Discuss morphological evidence of evolution. › Explain how physiology and biochemistry provide evidence of evolution. Review Vocabulary: › Fossil – remains of an organism or its activities New Vocabulary › › › › › › › › › › Derived trait Ancestral trait Homologous structure Vestigial structure Analogous structure Embryo Biogeography Fitness Mimicry Camouflage Chapter 15 Evolution 15.2 Evidence of Evolution Support for Evolution The fossil record Provide a record of species that lived long ago. Show that ancient species share similarities with species that now live. Glyptodont Armadillo The giant armadillo-like glyptodont, Glyptodon,is an extinct animal that Darwin thought must be related to the living armadillos that inhabit South America, Central America, and the southern United States. The fossil record is an important source of information for determining the Chapter 15 Evolution 15.2 Evidence of Evolution Support for Evolution Geographic Distribution The distribution of plants and animals that Darwin saw first suggested evolution to Darwin. Mara Rabbit Chapter 15 Evolution 15.2 Evidence of Evolution Derived traits are newly evolved features, such as feathers, that do not appear in the fossils of common ancestors. Ancestral traits are more primitive features, such as teeth & tails, that do appear in ancestral forms. Anatomically similar structures inherited from a common ancestor are called homologous structures. The forelimbs of vertebrates are adapted for different uses, but they all have similar bones. Similar structure; different function. Anatomically similar structures inherited from a common ancestor Analogous structures can be used for the same purpose and can be superficially similar in construction, but are not inherited from a common ancestor. Show that functionally similar features can evolve independently in similar environments. Same function; different structure Chapter 15 Evolution Analogous Structures Same function but different structure NOT inherited from common ancestor. Vestigial structures are the reduced forms of functional structures in other organisms. Evolutionary theory predicts that features of ancestors that no longer have a function for that species will become smaller over time until they are lost. Examples: Snake pelvis and human appendix. Chapter 15 Evolution 15.2 Evidence of Evolution Vestigial Structures Structures that are the reduced forms of functional structures in other organisms. Evolutionary theory Says features of ancestors that no longer have a function will become smaller over time until they are lost. Chapter 15 Evolution 15.2 Evidence of Evolution Comparisons of the similarities in organisms are seen in comparative anatomy and in the fossil record. Organisms with closely related morphological features have more closely related molecular features. An embryo is an early pre-birth stage of an organism’s development. Vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in the adult forms. embryo- it’s the earliest stage of development reptiles, birds, and mammals all have similarities tail, organs, eye placement etc… Common ancestry can be seen in the complex metabolic molecules that many different organisms share. Comparisons of the similarities in these molecules across species reflect evolutionary patterns seen in comparative anatomy and in the fossil record. Organisms with closely related morphological features have more closely related molecular features. The distribution of plants and animals that Darwin saw first suggested evolution to Darwin. Rabbit Mara The distribution of plants and animals that Darwin saw first suggested evolution to Darwin. Rabbit Mara Fitness – ability of an individual to survive and reproduce in a specific environment Adaptation – inherited characteristic that increases an organism’s chance of survival › Can be physical traits as well as behavioral traits Types of Adaptation › An adaptation is a trait shaped by natural selection that increases an organism’s reproductive success. › Fitness is a measure of the relative contribution an individual trait makes to the next generation. It is often measured as the number of reproductively viable offspring that an organism produces in the next generation. › Camouflage allows organisms to become almost invisible to predators. Some species have evolved morphological adaptations that allow them to blend in with their environments. › Mimicry is another morphological adaptation that allows one species to evolve to resemble another species. Antimicrobial resistance - An antibiotic is a medicine that slows or kills the growth of bacteria. Some bacteria have evolved a resistance to certain antibiotics. People infected with resistant bacteria can never Some features of an organism might be consequences of other evolved characteristics. They do not increase reproductive success. Features likely arose as an unavoidable consequence of prior evolutionary change. -behaviors that increase fitness For ex: aggression in bee’s Chapter 15 Evolution 15.2 Evidence of Evolution Camouflage Allows organisms to become almost invisible to predators Leafy sea dragon Camouflage- blend in with surroundings Camouflage- blend in with surroundings Chapter 15 Evolution 15.2 Evidence of Evolution Mimicry One species evolves to resemble another species. Western coral snake California kingsnake