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Diversity and Evolution SC.912.L.151 SC.912.L.15.10 SC.912.N.1.3 SC.912.N.2.1 SC.912.L.15.8 Prokaryotes • Prokaryotes were the earliest organisms on Earth and evolved alone for 1.5 billion years. • Two prokaryotic domains: Bacteria and Archaea Prokaryotes • have a cell wall external to the cell membrane • Lack membrane bound nucleus and organelles • Double-stranded DNA molecule is in a single ring shaped Evolution • Process by which species of organisms change over time • Thing evolve around us all the time • Based on scientific evidence such as… 1. 2. 3. 4. 5. Fossils/Paleontology Biogeography Comparative morphology/anatomy of organisms Comparative Embryology Analysis of amino acids and genetic material • DNA analysis…DNA fingerprinting! Terms to Know • Species – a group of organisms that share similar characteristics and can interbreed to produce fertile offspring – As species EVOLVE, they produce new traits and lose other traits…. • Adaptation – Any physical or behavioral trait that improves an organisms chance for survival and reproduction 1. Fossil Evidence for Evolution • Fossils: – Remains or evidence of organisms that have lived in the past – Provided clues of when different species lived • Law of Superposition – States that in undisturbed sedimentary rock, older rock layers lie beneath younger rock layers – By Identifying the fossils indifferent layers of rock and applying the law of superposition, scientists can determine: • when the certain organisms lived • The order in which things evolved Law of Superposition 2. Biogeography • Study of the distribution of Earth’s organisms • Continental Drift Hypothesis – States that the continents were once joined in a single, large landmass called PANGAEA – Pangaea broke up over millions of years and continents ended up where they are today – Fossil evidence shows that in addition to changing Earth’s surface, continental drift also changed the distribution of organisms on Earth 3. Comparative Anatomy/Morphology • Do other organisms have arms like us? • Many species share similar structures.. • Do flamingos and blue jays have feathers? – Yes…the presence of feathers suggest that both groups of birds descended from an animal with feathers – Flamingos and blue jays are more closely related than either one is to an animal without feathers (like us) Homologous Structures • Body parts of different organisms that have similar structure but NOT similar FUNCTION • Homologous structures DO indicate shared ancestor • • • • Analogous Structures Body parts that have a SIMIALR FUNCTION but NOT similar structure Body parts with Different structure, same function Do NOT indicate shared ancestry An analogous structure found in two different species Homologous vs. Analogous Structures • Homologous= Same structure, DIFFERENT Function • Analogous= Different Structure, SAME Function Comparative Anatomy Anatomical features that are similar in structure are called homologous structures, and they indicate common ancestry. Vestigial Structures • Structures that do not seem to play a role in the body functions of the organism – Appendix • Rats digestion • Humans no use…appendix is a vestigial structure • It can be concluded that the common ancestor of the human and rat had an appendix 4. Comparative Embryology • Study of embryos • Embryo early stage in the development of an organism • Scientists compare the development of the embryos of different species • Similarities in development =shared ancestor • More traits in common=more closely related Modern Organisms EVOLVED from COMMON Ancestors in an Evolutionary Chain 5. Chemical Evidence of Evolution • Chemicals found in living things also provide clues to ancestry..what chemical? – DNA!!! • Comparisons of the sequences of the nucleotides in DNA and the amino acids in certain proteins can also be used to show more common ancestry • More similarities in two DNA sequences or amino acid sequences = the more closely related the organisms are – DNA fingerprinting ALL organisms have DNA made up of the same Amino Acids… The only thing that’s different is the ARRANGEMENT/sequence of amino acids… The More similar AA sequences= the more closely related the organisms are! Similarities in Molecular Biology Common amino acid sequences suggest an evolutionary relationships between various species of organisms.
