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Evolution- “Change Over Time” All of the changes that have occurred in living things since the beginning of life on Earth History of the Earth 4.5 bya 3.5 bya 2.1 bya • Earth forms • 1st PROKARYOTES st •1 EUKARYOTES 700 million years ago… Evolution occurs over MANY generations Evolution occurs within POPULATIONS (NOT individuals) Evolution involves genetic changes in a SPECIES – (Members of a species interbreed to produce healthy, fertile offspring) Evidence for Evolution FOSSIL EVIDENCEProvides TRANSITIONAL LINKS Archaeopteryxlinks reptiles and birds Anatomical Evidence ANALOGOUS HOMOLOGOUS STRUCTURES STRUCTURES structures that are similar because they were inherited from a COMMON ANCESTOR similar in function, but NOT inherited from a common ancestor NOTE: similar structure, but NOT always function! NOTE: similar FUNCTION, but not STRUCTURE In other words… Sometimes we see structures in two species that are similar…some of them are: – Homologous (they are similar because of a common ancestor) – Analogous (they are similar because althouth they do NOT share a recent ancestor, they live in similar environments and have adapted to them similarly) 2 types of Evolution Evolution Types Convergent Evolution – Acquiring the same biological trait in unrelated lineages – These traits may be a result of occupying similar environments. Convergent Evolution Evolution Types Divergent Evolution – The accumulation of differences between groups which can lead to the formation of new species, usually a result of different groups of the same species adapting to different h environments, leading to natural selection defining the success of specific mutations. Divergent Evolution More Anatomical Evidence: Vestigial Structures Vestigial Structures are undeveloped structures that were functional in some ancestor, but are no longer needed in that organism. EMBRYOLOGYsuggests common ancestors BIOGEOGRAPHICAL EVIDENCE When we study the distribution of plants and animals on the planet, we notice: – Animals evolved differently in each of the biogeographical regions – We see evidence that as the continents drifted, organisms were separated and evolved. BIOCHEMICAL EVIDENCE Almost all living things use the same biochemical molecules – DNA, Protein, ATP Vast diversity came about by only slight differences in the same genes The more closely “related” the organisms are, the more similar their DNA Other Evidence… 1. Mimicry and Camoflauge 2. Antibiotic Resistance