* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Ch 15 Notes Teacher
Sexual selection wikipedia , lookup
Objections to evolution wikipedia , lookup
Sociocultural evolution wikipedia , lookup
Unilineal evolution wikipedia , lookup
Hindu views on evolution wikipedia , lookup
The Descent of Man, and Selection in Relation to Sex wikipedia , lookup
Natural selection wikipedia , lookup
Sympatric speciation wikipedia , lookup
Inclusive fitness wikipedia , lookup
Acceptance of evolution by religious groups wikipedia , lookup
Creation and evolution in public education wikipedia , lookup
Evidence of common descent wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Catholic Church and evolution wikipedia , lookup
Population genetics wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Chapter 15.1 Darwin’s Theory of Evolution by Natural Selection Section 1 Main Idea: Charles Darwin developed a theory of evolution based on natural selection. Developing the Theory of Evolution: Darwin on the HMS Beagle & The Galápagos Islands • When Darwin began his journey, most people thought the world was ~6000 years old, and that animals and plants were unchanging. • Darwin’s job on the Beagle was to be a naturalist, and to collect biological and geological specimens during the travels. • Darwin noticed that the different islands all seemed to have their own, slightly different varieties of animals. • Almost every specimen Darwin collected on the Galápagos was new to European scientists, though they were similar to species on mainland South America. • Island and mainland species should not have been so similar, unless mainland species had changed since arriving on the islands. Name_____________________ Date___/___/___ Hour______ Essential Questions Answer these essential questions to better understand the concepts in this chapter. What evidence convinced Darwin that species could change over time? _________ __________________ __________________ __________________ __________________ What are the four principles of natural selection?__________ __________________ __________________ __________________ __________________ __________________ __________________ How can natural selection change a population? ________ __________________ __________________ __________________ __________________ Vocabulary Developing the Theory of Evolution: Darwin continued his studies • Darwin hypothesized that new species could appear gradually through small changes in ancestral species. • Darwin inferred that if humans could change species by artificial selection – directed breeding to produce offspring with desired traits, then perhaps the same process could work in nature. • Darwin described the process of natural selection: some competitors would be better equipped for survival than others, those less equipped would die. • Principles of natural selection: • Individuals show variation • Variations are heritable • More offspring are born than can survive • Variations that increase reproductive success will be more common in the next generation Selective Breeding __________________ __________________ Artificial Selection __________________ __________________ Natural Selection __________________ __________________ Evolution __________________ __________________ The Origin of Species • Darwin published On the Origin of Species by Means of Natural Selection in 1859. • Today, scientists use evolution to mean cumulative change in a group of organisms through time. • Natural selection is not synonymous with evolution – it is a mechanism by which evolution occurs. Chapter 15.2 Evidence of Evolution Essential Questions Section 1 Main Idea: Multiple lines of evidence support the theory of evolution. How do fossils provide evidence of evolution? _________ __________________ __________________ __________________ __________________ Support for Evolution • The theory of evolution states that all organisms on Earth have descended from a single ancestor. • Recall that theories provide explanations for natural phenomena based on observation. • Darwin’s On the Origin of Species demonstrated how evolution might happen, and evidence of its occurrence. • Evidence for evolution comes from: the fossil record, comparative anatomy, comparative embryology, comparative biochemistry, and geographic distribution. Support for Evolution: The fossil record • Fossils show modern species resemble ancient species. • They also reveal that some species have changed very little. • The fossil record is an important source of information for determining the ancestry of organisms and the patterns of evolution. • Darwin predicted the existence of fossils intermediate in form between species, such as Archaeopteryx. • Researchers consider two major classes of traits when studying transitional fossils: • Derived traits are newly evolved features, such as feathers, that do not appear in the fossils of common ancestors. • Ancestral traits are more primitive features, such as teeth and tails, that do appear in ancestral forms. How does morphology provide evidence of evolution? _________ __________________ __________________ __________________ __________________ How does biochemistry provide evidence of evolution? __________________ __________________ __________________ __________________ Vocabulary Fossil_____________ __________________ __________________ Derived Trait_______ __________________ __________________ Support for Evolution: Comparative anatomy • Anatomically similar structures inherited from a common ancestor are called homologous structures. • Evolution predicts that an organism’s body parts are more likely to be modifications of ancestral body parts than entirely new structures. • Vestigial structures are structures that are the reduced forms of functional structures in other organisms. • Evolutionary theory predicts that features of ancestors that no longer have a function for that species will become smaller over time until they are lost. Ancestral Trait______ __________________ __________________ Homologous Structure __________________ __________________ Support for Evolution: Comparative anatomy • Analogous structures can be used for the same purpose and be superficially similar in construction, but are not inherited from a common ancestor. • Analogous structures show that functionally similar features can evolve independently under similar conditions. • An embryo is an early, pre-birth stage of an organism’s development. • Vertebrate embryos exhibit homologous structures during phases of development that become totally different structures in the adult forms. Support for Evolution: Comparative biochemistry • Common ancestry can be seen in the complex metabolic molecules that many different organisms share. • The more closely related species are to each other, the greater the biochemical similarity. Support for Evolution: Geographic distribution • The distribution of plants and animals were what first suggested evolution to Darwin. • The distribution of plants and animals around the world is studied in the field of biogeography. • Evolution is linked to migration patterns, climate, and geological forces (such as plate tectonics). Adaptation: Types of adaptations • An adaptation is a trait shaped by natural selection that increases an organism’s reproductive success. • Fitness is a measure of the relative contribution an individual trait makes to the next generation. • The better an organism is adapted to its environment, the greater its chances of survival and reproductive success. • Camouflage is a suite of morphological adaptations that allow an organism to blend into its environment. • Mimicry is a type of morphological adaptation where a species evolves to resemble another species. • Antimicrobial resistance develops in some bacteria in response to sub-lethal exposure to antibiotics. • Not all features of an organism are necessarily adaptive. • Some features are consequences of other evolved characteristics. • Helplessness of human babies: humans give birth at a much early developmental stage than other primates. • May be a consequence of larger brain size and upright posture Vestigial Structure __________________ __________________ Analogous Structure __________________ __________________ Embryo ___________ __________________ __________________ Biogeography_______ __________________ __________________ Fitness ____________ __________________ __________________ Camouflage ________ __________________ __________________ Mimicry___________ __________________ __________________ Chapter 15.3 Shaping Evolutionary Theory Section 1 Main Idea: The theory of evolution continues to be refined as scientists learn new information. Mechanisms of Evolution • Natural selection is not the only mechanism of evolution. • Evolution occurs at the population level, with genes as the raw material. Mechanisms of Evolution: Population genetics • Hardy and Weinberg showed that evolution will not occur in a population unless allelic frequencies are acted upon by forces that cause change. • Hardy-Weinberg principle states that when allelic frequencies remain constant, a population is in genetic equilibrium. • The Hardy-Weinberg principle can be numerically represented as: • Where: • p2 is the proportion of homozygous dominant • 2pq is the proportion of heterozygous • q2 is the proportion of homozygous recessive • For a population to be in genetic equilibrium according to the HardyWeinberg principle, it must meet five conditions: 1) No genetic drift 2) No gene flow 3) No mutation 4) Mating must be random 5) No natural selection • These five conditions are the mechanisms of evolutionary change. Mechanisms of Evolution: Genetic drift • Any change in the allelic frequencies in a population that results from chance is called genetic drift. • In smaller populations, the effects of genetic drift become more pronounced, and the chance of losing an allele becomes greater. • The founder effect results when a group of individuals with a different allele frequency than the original population becomes isolated. • Alleles that were infrequent in the original population may be common in the new population. • Happens when a subset of organisms settles in an area separated from their original population • Can result in large genetic variations in the separated population Mechanisms of Evolution: Genetic drift • A bottleneck results when population declines to a very low level and then rebounds. • The gene pool of the rebound population is similar to the low-level population, which may have reduced diversity. Essential Questions What are the conditions of the Hardy-Weinberg principle?__________ __________________ __________________ __________________ __________________ What patterns can be observed in evolution? __________________ __________________ __________________ __________________ What factors influence speciation?_________ __________________ __________________ __________________ __________________ Vocabulary Allele_____________ Hardy-Weinberg principle __________________ __________________ genetic drift __________________ __________________ founder effect __________________ __________________ bottleneck __________________ __________________ stabilizing selection __________________ __________________ directional selection __________________ Mechanisms of Evolution: Gene flow • A population in genetic equilibrium experiences no gene flow – it is a closed system. • Uncommon in natural populations – organisms migrate/move between populations • Random movement increases genetic variation within a population and decreases the genetic variation between populations. Mechanisms of Evolution: Nonrandom mating & Mutation • A population in genetic equilibrium must exhibit random mating. • This rarely occurs in populations – mating occurs between individuals in close proximity promotes inbreeding • Changes allelic frequencies, favoring individuals that are homozygous • A mutation is a random change in genetic material. • The cumulative effect of mutations in a population might shift allelic frequencies. • Most mutations are harmful, but some may be beneficial and become more common. Mechanisms of Evolution: Natural selection • Natural selection acts to select the individuals that are best adapted for survival and reproduction. • Three types of natural selection: 1) Stabilizing 2) Directional 3) Disruptive • Stabilizing selection operates to eliminate extreme expressions of a trait when the average expression leads to higher fitness. • Directional selection increases the expression of an extreme version of a trait and increases fitness. • Disruptive selection removes individuals with average traits, but retains individuals expressing extreme traits. • Sexual selection drives change in the frequency of a trait based on the ability to attract a mate. • Common in populations where males and females look significantly different • Some qualities that enhance mating success reduce odds of survival. Reproductive Isolation • Most scientists define speciation as the process whereby a population of sexually reproducing organisms changes so much that it can no longer produce fertile offspring with other populations. • Two types of reproductive isolation mechanisms prevent gene flow: Prezygotic and Postzygotic. Reproductive Isolation: Prezygotic isolation & Postzygotic isolation • Prezygotic isolating mechanisms operate before fertilization occurs. • Prevent reproduction by making fertilization unlikely • Often occur through geographic, ecological, or behavioral differences. • Postzygotic isolating mechanisms operate after fertilization and ensure that the resulting hybrid remains infertile. __________________ disruptive selection __________________ __________________ sexual selection __________________ __________________ prezygotic isolating mechanism __________________ __________________ postzygotic isolating mechanism __________________ __________________ allopatric speciation __________________ __________________ sympatric speciation __________________ __________________ adaptive radiation __________________ __________________ gradualism __________________ __________________ punctuated equilibrium __________________ __________________ Reproductive Isolation: Prezygotic isolation & Postzygotic isolation • Hybrid offspring either cannot develop or cannot reproduce. Speciation: Allopatric and Sympatric speciation • For speciation to occur, populations must diverge and become reproductively isolated. • Two types of speciation: allopatric and sympatric. • Allopatric speciation occurs when populations are divided by a physical barrier. • Most scientists think allopatric speciation is the most common type of speciation. • Sympatric speciation occurs without a physical barrier; populations remain in close proximity. • Common in plants due to polyploidy Patterns of Evolution: Adaptive radiation • Adaptive radiation takes place when a large number of species arise from a single common ancestor in response to an ecological opportunity. • Often follows large-scale extinction events or creation of new habitat Patterns of Evolution: Coevolution • Coevolution occurs when relationships between species are so close that they influence each other’s evolution. • Mutualism – both species benefit • Coevolutionary arms race – parasitic or predatory relationship Patterns of Evolution: Convergent evolution • Unrelated species evolve similar traits even though they live in different parts of the world. • Occurs in environments that are geographically distinct but ecologically similar Patterns of Evolution: Rate of speciation • Evolution proceeds in small, gradual steps according to a theory called gradualism. • Punctuated equilibrium states rapid spurts of genetic change causing rapid speciation punctuate long periods of little change.