G10 Q2 Module 6 Topic 1 Evolution PDF

 LEARNING OBJECTIVES At the end of the lesson you should be able to: - Explain how fossil records, comparative anatomy, and genetic information provide evidence for evolution. - Explain the occurrence of evolution. Guide Questions Fossil Evidence of Evolution How do fossils form?...

 LEARNING OBJECTIVES At the end of the lesson you should be able to: - Explain how fossil records, comparative anatomy, and genetic information provide evidence for evolution. - Explain the occurrence of evolution. Guide Questions Fossil Evidence of Evolution How do fossils form? How do scientists date fossils? How are fossils evidence of biological evolution? What is Evolution?  What are FOSSILS? Fossils are preserved remains or traces of living organisms. After an animal dies, any soft tissues often decay or eaten by animals Only the dead animal’s hard parts, such as bones, shells, and teeth leave fossils Paleontologists: scientists who study fossils  Types of Fossils Molds ○ An imprint left by the shell on the rock that surrounded it. ○ Mold forms when the hard part of the organism is buried in sediment.  Types of Fossils Casts ○ Water carrying dissolved minerals and sediments may seep into the mold ○ The sediments harden and take the shape of the mold making a copy of the fossil ○ A cast is a solid copy of the shape of a fossil or organism http://web.archive.org/web/20061013053847/http://www.classzone.com/books/earth_sc ience/terc/content/visualizations/es2901/es2901page01.cfm?chapter_no=visualization  Types of Fossils Petrified ○ Minerals replace all or part of an organism ○ Water rich in dissolved minerals seep into spaces of the organism  Types of Fossils Carbon Films ○ Extremely thin coating of carbon on rock ○ When sediment buries an organism, some of the materials that make up the organism evaporate or become gases ○ These gases escape from the sediment, leaving carbon behind, which helps in preserving the organism  Types of Fossils Trace ○ Provide evidence of the activities of ancient organisms ○ A fossilized footprint is a trace fossil  The Fossil Record The fossil record is made up of all the fossils ever discovered on Earth. The fossil record provides evidence that species have changed over time. Based on fossil evidence, scientists can recreate the physical appearance of species that are no longer alive on Earth.  Determining a Fossil’s Age Relative dating estimates the time during which an organism lived. ○ It compares the placement of fossils in layers or rock.  Geologic Time Scale The Geologic Time Scale divides Earth’s history based on major past events.  Geologic Time Scale Extinctions occurs when the last individual organism of a species dies. A mass extinction occurs when many species become extinct within a few million years or less. Extinctions can occur when environments change. The fossil record is evidence that horses descended from organisms for which only fossils exist today.  Charles Darwin’s Theory of Evolution He developed a theory of evolution based on Natural Selection. ○ Traits that are best adapted to the environment are bred more often causing gradual change in species over time. ○ Organisms not possessing desired traits either die or do not have as many offspring Charles Darwin’s Theory of Evolution Darwin found that each island in the Galápagos had a different environment, and tortoises looked different depending on which island environment they inhabited. Domed Tortoise - Isabela Island Why do domed tortoises have short necks? Tortoises with dome-shaped shells live on islands where there is an abundance of vegetation close to the ground, making it less necessary for the animals to raise their heads to feed. Intermediate Tortoise - Santiago Island Saddleback Tortoise - Española Island Why do saddleback tortoises have long necks? To allows them to stretch their necks higher to reach vegetation that grows above the ground. This species of tortoise might have lived on the hotter and drier island of the Galapagos so their neck extended farther to reach for vegetation.  How evolution occurs in 4 steps? 1. Reproduction: More offspring are produced than can ever survive 2. Variation: Exists within the group of offspring due to sexual reproduction (meiosis and fertilization) 3. Competition: Offspring compete with one another and other species for resources (food, shelter, mates etc…) 4. Selection: The environment determines which one competed the best and has a chance to survive and pass on its successful genes(alleles)! Charles Darwin’s Theory of Evolution Survival of the Fittest ○ Some organisms are better suited for their environment than others; those best suited will survive Charles Darwin’s Natural Selection Natural selection is based on 4 main ideas: Natural selection is based on 4 main ideas: Natural selection is based on 4 main ideas: Natural selection is based on 4 main ideas: Guide Questions 1. What is it called when an animal blends into its environment? i. Camouflage 2. Why do animals camouflage? i. Animals use camouflage to mask their location, identity, and movement to avoid predators or for predators to sneak up on prey. 3. How do animals camouflage? i. Color or pattern matching with their surroundings  Adaptation Adaptation is a change or process of change by which an organism or species becomes better suited to its environment. Types of Adaptations: 1. Camouflage is a morphological adaptation that allows an organism to blend into its environment 2. Mimicry is a morphological adaptation where a species evolves to resemble another species 3. Antibiotic resistance develops in some bacteria, making them resistant to antibiotic treatments.  Camouflage Why do animals camouflage? Camouflage Military operations  Mimicry Why do animals mimic others?  Charles Darwin developed his theory of evolution partly by observing organisms in their natural environment. Natural selection occurs when organisms with certain variations live longer, compete better, and reproduce more often than organisms that do not have the variations.  Adaptations occur when a beneficial variation is eventually inherited by all members of a population. Guide Questions Biological Evidence of Evolution What evidence from living species supports the theory that species descended from other species over time? How are Earth’s organisms related?  Evidence of Evolution Comparative anatomy is the study of similarities and differences among structures of living species. ○ Homologous structures ○ Analogous structures ○ Vestigial structures ○ Embryology  SAME STRUCTURE SAME ANCESTRY DIFFERENT FUNCTION The forelimbs of these species are different sizes, but their placement and structure suggest common ancestry.  SAME STRUCTURE DIFFERENT ANCESTRY SAME FUNCTION  Evidence of Evolution Embryo is the first 9 weeks of vertebrae development. The science of the development of embryos from fertilization to birth is called embryology. Embryonic structures of different species suggest evolution from a distant and common ancestor. All vertebrate embryos exhibit pharyngeal pouches at a certain stage of their development. These features, which develop into neck and face parts, suggest relatedness.  By comparing the anatomy of organisms and looking for homologous or analogous structures, scientists can determine if organisms had a common ancestor.  Some organisms have vestigial structures, suggesting that they descended from a species that used the structure for a purpose.  Scientists use evidence from developmental and molecular biology to help determine if organisms are related.