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Transcript
EVIDENCE of EVOLUTION Review… CHAPTER 15.2 OBJECTIVE: 1. Describe the various forms of evidence that support the idea of evolution – fossils, morphology, and biochemistry… Evidence of Evolution • recall - a theory provides an explanation for a • evolution is defined as the cumulative changes in groups of organisms through time • natural selection is not synonymous with evolution.... natural selection is a mechanism by which evolution occurs Support for Evolution... There are five categories that offer evidence to support evolution… natural phenomenon based on observations • theories explain available data and suggest further areas for experimentation • the theory of evolution states that all 1. The Fossil Record ♦ fossils provide a record of species that lived long ago and supply some of the most significant evidence for evolutionary change. organisms on Earth have descended from a common ancestor 2. Comparative Anatomy ♦ researchers consider two major classes of traits when studying fossils - derived and ancestral traits homologous structures: anatomically similar structures inherited from a common ancestor derived traits: newly evolved features (feathers) that do not appear in the fossils of common ancestors ancestral traits: primitive features (teeth, tails) that appear in ancestral forms 1 analogous structures: structures used for the same purpose and can be superficially similar but are not inherited from a common ancestor (wings from a bird / insect) vestigial structures: structures that 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 it is lost 3. Comparative Embryology vertebrate embryos provide glimpses into evolutionary relationships ♦ while analogous structures do not indicate close evolutionary relationships, they do show that functionally similar features can evolve independently in similar environments scientists have found that vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in adult forms… embryo: an early, pre-birth stage of an organism’s development all vertebrate embryos have a tail and pharyngeal pouches – in fish they develop into gills and in reptiles, birds and mammals they become parts of the ears, jaws and throats. 4. Comparative biochemistry scientific data shows that common ancestry can be seen in the complex metabolic molecules that many different organisms share… complex proteins, DNA /RNA these shared embryonic features indicate that vertebrates evolved from a common ancestor organisms with closely related morphological features have more closely related molecular features 2 5. Geographic distribution biogeography: the study of the distribution of plants and animals around the world evolution is intimately linked with climate and geological forces, especially plate tectonics, which helps to explain many ancestral relationships and geographic distribution seen in fossils and living organisms today… ADAPTATION ♦ an adaptation is a trait shaped by natural selection that increases an organism’s reproductive success ♦the better an organism is adapted to its environment, the greater its chances for survival and reproductive success camouflage: evolved morphological adaptations that allow them to blend in with the environment mutation: a random change in genetic material mimicry: one species evolves to resemble another species Shaping Evolutionary Theory 1. speciation: the evolutionary process by which new biological species arise allopatric speciation: a physical barrier divides one population into two or more populations 2. patterns of evolution adaptive radiation (divergent evolution) is when one species gives rise to many species in response to the creation of a new habitat or another ecological change – this occurs relatively quickly coevolution: many species evolve in close relationship with another species – mutualism, parasitism) sympatric speciation: a species evolves into a new species without a physical barrier – the ancestor species and the new species live side by side during the speciation process 3 convergent evolution: unrelated species evolve similar traits even though they live in different parts of the world convergent evolution occurs in environments that are geographically far apart but have similar ecology and climate… 4