| Term | Definition |
|---|
| the 2 concept that are fundamental to the theory of evolution are? | 1) the characteristics of living thing change with time, 2) the change is directed by natrual selection * the characteristics is not in an individual during it's lifetime but in a population |
| Evolution | The change in the genetic makeup of a population over time |
| Each individual in a population has a unique geneotype because the gametes used in fertilization are unique leads to | 1) Mutations- Especially in gametes, 2) meiosis-crossing over and independent assortment |
| Genetic recombination | the sum total of all the gene mixing that occurs during sexual reproduction |
| Another important concept is that sexual reproducting organims tend to reproduce far ________ offspring than is necessary to maintain the population. | more |
| Aquired Characteristics | Gained during lifetime, and are not passed on. Examples: Learned behaviors, phenotypic changes due to the environment |
| Theory of natural selection | States that individuals with genes that make them better adapted to their surroundings and are more likely to have higher survival rates and produce more offspring |
| who first proposed the theory of natural selection? | Charles Darwin in his book, on the origin of species by means of natural selection or the preservation of favored races in the struggle for life. |
| What is the struggle for life? | Includes not only open conflict, but more often competition for resources that are in short supply. Example: Nesting materials, nest sites, food, water, sunlight, etc |
| Natural selection works by means of ________? | Differential reproduction |
| What is differential reproduction? | Organisms with genes that make them more fit will reproduce more offspring there for the favorable gene or genes will become increasingly common amoung the population |
| Natural selection works by means of what? | Differential reproduction. |
| Gene frequency | A measure of how often a given gene turns up in the gametes of a populationl |
| Gene frequencies only change when? and their change is ____? | They only change when there is a reason for change and their change is slow. |
| Gene frequencies remain the same only if what 4 assumptions are met? | 1) population is large enough so that chance alone or accidental death will not change gene frequencies, 2) mutations must not occur, 3) there can be no immigration or emigration, 4) reproduction must be completely random |
| The four conditions and the resulting stability in gene frequencies are known as? | Hardy-Weinberg law. |
| But the conditions that the Hardy-Weinberg law states do not always hold true. What are the 4 reasons why? | notes |
| Gene flow | Over time, genes of a species are passed from one generation to another and from one geographic region to another. |
| species can move to a new geographic area by? | 1) Traveling under its own power, 2) Be carried by storms and winds, 3) attached to other organisms or human-transported objects. |
| exotic species | most animals we consider pests, species introduced because of human activities. They often become pests because there are no natural enemies or competitors in their new home, |
| Two questions are involved in the study of speciation? | 1) Can one species give rise to another? 2) what factors contribute to the production of new species? |
| Geographic isolation | Sometimes a portion of the gene pool becomes seperated from the rest of the gene pool by some geographic change. |
| Geographic barriers | The geographic features that cause geographic isolations. Examples... Mountains, oceans, rivers, deserts, etc |
| Following geographic isolation the group of isolated organisms will often experience different environmental conditions than the main population such as? | Rocky mountains, more rainfall |
| These environmental differences will act as natural _______ and cause differences to arise between the gene pools? | Selecting agents. |
| Speciation | The process of generating new species. Only occurs if gene flow between the two isolated pops does not occur even after the geographic barrier are removed. |
| What are the 3 steps of speciation? | 1) geographic isolation of the population (allopatric population), 2) differences in selecting agents---genetic differences, 3) genetic differences so great----Reproduction impossible between the 2 groups even if they once again share the same range (symatric populations). |
| Mechanisms that prevent interspecies matings are called? | Reproductive isolating mechanisms or genetic isolating mechanisms. |
| Ecogeogrpahic isolation | Occurs when 2 populations become so specilized for different environment conditions---can't survive where other occurs. Example: sycamore in eastern U.S.and the oriental plan tree in the Mediterranean can be crossed and produce fertil offspring but cannot survive in each others home range. |
| Habitat Isolation | Occurs when 2 sympatric populations occupy different habitats within their common range--- genetically determined preference for different habitats isolates gene pools. Example: Bufo woodhousei and Bufo Americanus are closely related toads that can cross and produce fertil offspring but one lives in streams and the other lives in ponds---Dont mate with each other |
| Seasonal Isolation | Occurs when 2 closely related sympatric species breed during different seasons. Example: 2 sympatric termite species in souther florida. One breeds march-may, other in fall and winter---don't mate with each other. |
| Behavioral Isolation | Occurs when behavioral cues are associated with successful courtship and mating. Example: Many ducks and fish have elaborate "dances" that are necessary. Fireflies- frequencey of light;some use to trap males, Cricket songs- can't tell the apart by sight only sound. |
| Mechanical isolation | occurs when structural differences between 2 cloely related species prevents matings (usually differences in shape of genitalia) examples: Many similar insects have different genital shapes. |
| Gametic Isolation | Occurs when 2 different species are able to mate, but egg and sperm will not form a zygote. Example: sprem is rapidly demobilized when drosophilia virilis and drosophilia americana mate---bad environment for sperm. |
| Developmental Isolation | Occurs when mating and fertiliation between two species are successful but the embryo does not develop properly. Example: many fish, sheeps and goats |
| Hybrid Inviability | Occurs when a hybrid resulting from interbreeding dies before reproducing or is so weak or malformed that it can't reproduce. Example: Mnay tobacco hybrids form tumors on roots and die before reproduce. |
| Hybrid sterility | Occurs when a hybrid is vigourous but sterile. Example: Female horse and male donkey= mules (sterile) |
| Selective hybrid elimination | Occurs when a hybrid is capable of reproducing but they and there offspring are less fit and soon eliminated from the population. within a few generations. If just as fit, and the species are sympatric---soon 1 species. |
| Polyploidy | plants can form new species by another method of speciation= polyploidy. The number of chromosome present is increased. |
| creationists believe? many people believed this also for centuries | the various species of plants and aminals remain unchanged since their creation |
| In mid 1700's who was gene buffon? | Thought animals might change over time, but did not come up with a mechanism that would cause evolution. |
| Who sugested a process by which evolution would occur? | Jean Baptiste de Lamarck. |
| What did he suggest? | That aquired characteristics could be passed on to offpring. |
| What did he hypothesis? | Giraffes started out with short necks and constantly stretched their necks to get at the food so their necks got slightly longer over a lifeime and slightly longer necks passed on to offspring, necks of garaffes as a whole got longer and longer. |
| Why was Lamarck wrong? | notes |
| Evolutionary trees | Trace evolutionary changes over time. |
| at least ___ percent of all species that ever existed are now extinct? | 99% |
| Teh baisc pattern of evolution is? | divergent evolution. |
| divergent evolution? | speciation events cause branches in the evolution of a group of organisms. |
| Adaptive radiation | A rapid increase in the number of kinds of closely related species, occurs as an "explosion" of new species from one common ancestor |
| what are the two situations of adaptive radiation? | 1) An organism invades a previously unexploited environment. example: amphibians, galapagos finches took over roles held by other species elsewhere in the world. 2) an organism envolves a new set of characteristics that allows it to displace the organims that previously occupied an env. niche reptiles replace amphibians (dry skin;egg dev on land), mammals replaced reptiles (warm blooded) |
| Convergent evolution | Occurs when organisms of widely different backgrounds develop similar characteristics. for example: birds, insects, and bat all have wings and can fly but had no common ancestor with wings. |
| Rates of evolution can vary greatly, but usually evolutionary time is measured in? | Thousands or millions of years (big diff between thousands and millions) |
| Since natural selection is driven by the environment? | rapid changes in the environment cause relatively rapid changes in the organisms present. |
| Microevolution | the type described by Darwin----slow, progressive change |
| Macroevolution | Has recently been proposed by some scientists-- whole groups of characteristics change at the same tims--reptiles, mammals. Many new species appear, many old species become extinct. much of fossil record supports this |
| Punctuated equilibrium | Pattern of slow change for millions of years followed by rapid change. |
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