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 biochemical structural Which of these are NOT used to find biochemical or molecular relationships between organisms? Fossils DNA Proteins Amino Acid Sequences Fossil Evidence:Scientists use the age of fossils as evidence for evolution. There are two ways of dating fossils: relative dating and absolute dating. Relative dating uses a fossil's location in rock layers to determine that fossil's approximate age. Fossils found deeper in the ground are usually the oldest. Using the layers, a paleontologist can therefore know that a fossil found in a bottom layer at the dig site is older than a fossil found in a top layer. Absolute dating determines the fossil's actual age by measuring the amount of an element called carbon-14 in the fossil. There is a mathematical formula that will calculate the rate of decay of this element. By measuring the carbon-14 levels and pllugging it into the math formula, the scientist can know an actual number of years old a fossil is. What are two ways of finding the age of a fossil? Absolute dating and Relative datingWhat does relative dating use to determine age? Location in the layers of the rockWhat does absolute dating use to determine age? Carbon-14 levels and a mathematical formulaWhy is the element carbon-14 important for paleontologists? Gives absolute ageWhich layer would be the oldest at a dig site? Bottom layer 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. Convergent Evolution: The organisms do NOT come from a common ancestor, but evolve similarly in structure or function because they live in the same type of environmentDivergent Evolution: The organisms have a common ancestor but evolve differently and branch out to make an evolutionary treeCoevolution: One organism causes another to change in response because they live in close association Convergent Evolution In the ocean surrounding Antarctica, there are fish that survive the cold water by using a molecule made of glycoproteins (a sugar and protein together) that circulates the blood and keeps it from freezing. Certain kinds of worms that live in the Arctic ocean also make antifreeze proteins that help them live in icy water. Whales, sharks, and penguins all have streamlined bodies and fins for moving in water even though they belong in different classes of animals (whales = mammals, sharks = fish, penguins = birds) This kind of evolution is proven by DNA analysis and results in organisms with different ancestors becoming more alike as they adapt to similar environments. Ostriches (birds) and giraffes (mammals) are both native to the savannahs of Africa. They share the same characteristic of a very long neck. This picture shows: This is an example of: Divergent Evolution The Galloti antlantica and Galloti galloti lizards (those are their scientific names!) evolved through natural selection from a common ancestor into a wide variety of different looking lizards. The Galapagos tortoises share a common ancestor, but have necks of different lengths to best reach the food they need in their environment. Adaptive radiation is an example of this type of evolution. The Galapagos finches evolved through natural selection from a common ancestor into a wide variety of different looking species of birds. The beaver in North America and the capybara in South America share a common ancestor, but have evolved over time to look different. Ostriches are native to the savannahs of Africa, while penguins live in the polar regions. Although ostriches and penguins are closely related, they look very different. This is a picture is: Diagramof what? Coevolution Ants are the correct size and weight needed to open the flowers for the peony plant. The peony plant provides food for the ant and the ant fertilizes the peony's flowers. Hummingbirds hae a beak just the right length to reach the nectar in a cardinal flower and as they feed their foreheads bump into the pollen structure. Cardinal flowers are red which hummingbirds can see but bees can't. Cardinal flower's pollen structure is just the right length for the hummingbird to pick up pollen as it feeds.