Name________KEY_____________ Evolution Study Guide Biolo gy Evolution Study Guide 1. What is evolution? – the process by which modern organisms changed over time from ancient common ancestors. 2. What is artificial selection? – nature provides variation (variety) in organisms’ traits, but humans choose to breed those organisms that have the most useful traits. – Give an example. i. Example: humans breed cows that produce the most milk. ii. Example: humans breed trees that create the most fruit. 3. What is another name for natural selection? – AKA: “survival of the fittest” 4. Describe an animal that is very fit in its habitat. – finches on the Galapagos islands have a beak size adapted to the type of food that they eat. 5. Name the 3 parameters of evolution by natural selection. • 1. Struggle for existence – more organisms are produced than can survive. 2. Variation and adaptation – some variations are better suited. 3. Survival of the fittest – individuals with adaptations that are well suited to their environment survive and reproduce. • Fitness – measure of how well an organism survives/reproduces. 6. What is an adaptation? – – heritable characteristic that increases an organism’s ability to survive and reproduce. 7. What is competition? What types of resources do organisms compete over? – Competition – individuals or groups of organisms compete for similar resources (territory, mates, food, water, etc.) in the same environment. 8. What is common descent? – Common descent – all species (living and extinct) descended from a common ancestor. – Over many generations, adaptations caused a successful species to evolve into a new species. 9. What provides evidence for this “descent with modification”? – The fossil record provides evidence for this “descent with modification”. 10. What is Divergent Evolution? a. single species or group of species evolve over a short period of time into different forms living in different ways due to a change in environment that makes new resources available. b. Ex. Dinosaurs, Darwin’s finches. 11. What is Convergent Evolution? – similar structures are produced in distantly related organisms. • Ex. Mammals that feed on ants/termites evolved independently 5 times. 12. Name 1. Geographic Species Similar and describe the 7 pieces of evidence for evolution. Distribution of Species of animals on different continents had similar structures and behaviors. selection pressures caused animals to evolve common features. 2. Fossils A fossil is the preserved or mineralized remains (bone, tooth, shell) or trace of an organism that lived long ago. 3. Anatomy Homologous Structures – parts of different organisms (that are often quite dissimilar) that developed from the same ancestral body parts. o Are similar in structure but differ in function! 4. Physiology Analogous structures -- structures that are similar in appearance and function but have different origins and usually different internal structures. o Differ in structure, similar in function. Vestigial structures – any body structure that has reduced or no body function. o As species adapt to environments the change in form and behavior and continue to inherit these structures as part of the body, even though they have no function. 5. Embryology Embryos of different species in early development are indistinguishable from each other. Illustrates descent from a common ancestor. 6. Universal Genetic Code The genetic code of all organisms on Earth (bacteria, yeast, fruit flies, humans) is the same! o Example: the AUG codon always codes for the amino acid methionine. 7. Biochemical Homology Similar DNA, RNA, and amino acid sequences amongst species in same taxonomic group. 13. In a population of wooly worms, the number of green individuals increased over time. What happened to the allele frequency of the allele for green color? – -the allele frequency for green color increased 14. What is the main source of genetic variations in populations? -mutations! These mutations occur randomly. Not all mutations affect an organism’s fitness. 15. If a mutation occurs in a skin cell, does that mutation get passed on to the offspring of that individual? – no- Only heritable mutations matter for evolution. – – – 16. Name and describe the 3 types of selection in populations. • • • Directional Selection – organisms at one end of the curve have a higher fitness than those in the middle or at the other end. Stabilizing Selection – organisms in the center have highest fitness. Disruptive Selection – organisms at the ends of curve have highest fitness. 17. Name and describe the 3 other sources of changes in allele frequencies. • Genetic drift – change in allele frequency that occurs in small populations due to random chance. • Genetic bottleneck – change in allele frequency following a dramatic reduction in population size. • Founder effect – change in allele frequency following migration of a small subgroup out of the population to start a new population. 18. What is speciation? • Species – population of organisms that can interbreed and produce fertile offspring • Speciation – evolution/formation of a new species. 19. – – 20. 21. What is reproductive isolation? Reproductive isolation occurs when 2 populations can’t interbreed - causes speciation! Once reproductive isolation occurs, natural selection increases the differences between the separated populations. Name and describe the 5 Mechanisms of reproductive isolation. 1. Behavioral isolation – different courtship. 2. Ecological/habitat isolation – can only mate in specific or preferred habitats. 3. Mechanical isolation – no sperm is transferred. 4. Gametic isolation – no fertilization of egg occurs. 5. Temporal isolation – reproduce at different times. What is geographic isolation? – population becomes divided (isolated) by a physical barrier. 22. – 23. – What is gradualism? Gradualism – slow, steady change leading to new species. What is punctuated equilibrium? Punctuated equilibrium – brief periods of rapid change leads to the formation of new species.