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Evolution Evidence: 1. 2. 3. 4. 5. Adaptations (Natural Selection) Comparative Biochemistry (DNA) Comparative Anatomy Comparative Embryology Fossils Remember Darwin? The idea of Natural Selection leads to “Descent with Modification” Drawing Box Notes Title “Evidence of Evolution” 1. 2. 4. 5. 3. Summary 1. Adaptations: features suited to a particular environment that allow organisms to survive Inuit people, who live in the extreme cold of the Arctic, have short, stout bodies that conserve heat. Masai people, who live in the arid lands of eastern Africa, have tall, lean bodies that disperse heat well. Bird Beak Adaptations: Evidence #1 - Adaptations 1. Draw ONE organism and identify an adaptation for it. 2. List the 4 tenants of Natural Selection 2. Comparative Biochemistry • Similar DNA sequences= • Similar Gene segments of the DNA • Code for similar traits • In closely related species 3. Comparative Anatomy: Structural similarities link related species Homologous Structures: Two species, in which share a common ancestor. – At some point, there was isolation within the species and different evolutionary paths were taken Divergence can lead to HOMOLOGOUS structures Common ancestor Two new species Analogous Structures: • Two species, in which DO NOT share a recent common ancestor. – Due to similar environmental pressures, two unrelated species can develop the same trait Convergent Evolution can lead to analogous structures NO recent common ancestor Develop similar traits Comparative Anatomy Analogous: 1. Different ancestors 2. “analogy”=like 3. Different underlying structures 4. Same Function 5. Similar Environments Homologous: 1. Same ancestor 2. “homo”=same 3. Same underlying structures 4. Different Functions 5. Different Environments Vestigial Structures: • Traits that are no longer used, but still evident in the genetic code. • Proof that recent common ancestors had the trait! The top 10 Vestigial Structures The Wings on Flightless Birds • The Cassowary, the sexier, but less-wellknown flightless bird. Kiwi bird in Australia. Hind Leg Bones in Whales • Whale skeleton showing pelvis and thigh bones. Snake hind limbs. Erector Pili and Body Hair • When a rabbit is scared, its hair stands on end. When a human is scared, he or she calls the police. The Human Tailbone (Coccyx) • The human tailbone doesn't do much, but really hurts if you land on it. The Blind Fish Astyanax Mexicanus and Blind Mole rat • Have eyes Can’t see Wisdom Teeth in Humans • They need regular brushing but did they come from Apes? The Sexual Organs of Dandelions • Send in the clones ... Fake reproduction in Virgin Whiptail Lizards (Vestigial Behavior) • Feminist lizards take the male out of the picture. Male Breast Tissue and Nipples • They are not fully functional and, because cancer can grow in male or female breast tissue, the tissue can be dangerous. The Human Appendix • In 2000, in fact, there were nearly 300,000 appendectomies performed in the United States, and 371 deaths from appendicitis. Evidence #3 – Comparative Anatomy Explain how each of the following is evidence for evolution and provide ONE example of each: 1. Homologous Structures2. Analogous Structures3. Vestigial Structures- Embryological Development Similar embryo development in closely related species Evidence #4 – Embryonic Development Anatomy 1. Explain what scientists conclude from comparing the embryos of organisms to others. 2. Do you think this is a valid piece of evidence? Why or Why Not? 5. Fossil Evidence • Once living remains of organisms • Limited 1.Type of material preserved (bone, shell, impressions, amber) 2.Incomplete record 3.Easily disrupted Plant Fossil Evidence Law of Superposition • Sedimentary layers are deposited in a time sequence • Oldest rock on the bottom, youngest at the top Youngest Oldest Dating Fossils • Relative Age – describes approximate age of fossil relative to location. – Ex. “This fossil is located beneath that fossil, so it is relatively older.” – Law of superposition • Absolute age – Age of a fossil in years – Can be calculated using radioactive dating – Ex. “This fossil is approximately 1 million years old.” Evidence #5 - Fossils 1. Draw an image that demonstrates the “Law of Superposition” Rules: - Represent 4 layers - Draw ONE organism in each layer to represent the relative age of the fossils. Box #6 - Summary What conclusions can scientists make based on all of this previous (#1-5) evidence? Summarize this in one BOLD statement