Evidence for Evolution

Fossil Record Study of the remains of organisms from other eras Molecular Evidence Study of the similarities between DNA, amino acid sequences, and other molecules in organisms Vestigial Organ Primitive organ that no longer functions but could be a clue to a function from the past Comparative Anatomy Study of similarities in external structures Embryology Study of the development of organisms before they are born to discover similarities This picture shows a transitional fossil. Why is it considered transitional? It connects two different groups of organisms - fish four-legged terrestrial organisms It has scales It transitions from a fossil to a real animal during its lifetime It had lungs but also gills Why are fossils important for studying evolution? The tell us every single organism that ever lived in the past. The aren't important because making fossils are very difficult to do in nature. They give us information about organisms that lived in the past (some of them extinct) and also help us explain evolution from ancestors This picture represents different geological layers from different periods with fossils. Each of these layers is called a strata. The oldest are in bottom, in this case it is the Trilobites. The youngest are in the upper layer near the surface, in this case the ferns. What type of evidence for evolution does this picture show us? That one is fish and another is humans. That there is a tail and gills. That species that look dissimilar can actually share a common ancestor because they develop similarly. A dolphin and a shark are two aquatic animals that have analogous structures in their bodies. Analogous structures are those with the same function but different origin, due to convergent evolution. Their analogous structures are fins to swim. They both have fins because they adapted to live in the same environment of water; however, they do not share a common ancestor. Convergent evolution means that they are not related, but both evolved the same types of structures. Analogous structures are not used as evidence for evolution. The leg bone in a whale is an example of a vestigial structure because it is no longer used but gives clues about the past and the whale's ancestors he evolved from. Vestigial Structure A structure in a species with no function but is a clue about past functions and evolutionary history Information from Vestigial Structures Past functions, evolutionary relationships, common ancestors Examples of Vestigial Structures Coccyx in humans (tailbone), appendix, eyes on a blind cave fish, wisdom teeth HUMAN : AT-GCA-TAC-GGA-TGA-CAT-TTADOG: AAT-GGA-TTT-GAA-TGA-CAA-CTACHIMPANZEE: AAT-GGA-TAC-GGA-TGA-CAT-TTAFLY: ATT-ACA-TAT-CGC-CGT-CAT-TTAMUSHROOM: ATT-AAA-TAT-CCA-AAA-CAA-CTAUsing the sequences of DNA above, which two organisms are the most closely related? dog and fly human and chimpanzee mushroom and fly What kind of evidence for evolution is the above question? fossils embryological molecular anatomical Which of these are NOT used to find biochemical or molecular relationships between organisms? Fossils DNA Proteins Amino Acid Sequences What does the study of embryology show when comparing most vertebrates? They start off looking the same and having similar structures. What is a homologous structure? Body parts that are similar in both structure and function. What is a vestigial organ? A body part that is no longer used. How does the study of genetics and DNA help the study of evolution? They can show how closely related species are, and therefore how the must have evolved. If two species share a high percentage of their DNA, then it's likely that... their common ancestor lived long ago their common ancestor lived more recently they do not have a common ancestor one species descended directly from the other species