BIOL 1108 1st EditionExam # 1 Study Guide Lectures: 3 – 12Lecture #3 (August 16)I. Concept 22.3Evolution is supported by an overwhelming amount of scientific evidence and there are four processes by which evolution occurs: direct observation of evolution, homology, thefossil record, and biogeography. Direct observations of Evolutionary change- Natural selection in response to introduced plant species: Many animals have created adaptations in order to feed on different plants. For example, the soapberry bug in south Florida feeds on the native plant, the balloon vine. The soapberry bug eats the seed inside the vine by using its beak. However, in centralFlorida the soapberry bugs feed on goldenrain trees. The bugs feed most efficiently when their beak is the same depth, as the seed in the fruit. On averagethe soapberry bug that lives in south Florida has a higher beak length than that of the central Florida bug. This is because the balloon vine seeds are deeper thanthat of the goldenrain trees. From the results we can conclude that a change in size of the soapberry bug’s food source can result in evolution by natural selection for matching beak size.- The evolution of Drug-Resistant Pathogens: In 1959, scientist developed methicillin, a powerful antibiotic. Within two years, methicillin-resistant strains appeared. This happened because some bacteria were able to synthesize their cell walls without methicillin affecting it. These individuals reproduced and passed on the resistant genes allowing more resistant pathogens to be created. Natural selection is not a creative mechanism; it is a process of editing. Natural selection depends on time and place. It favors those characteristics in a genetically variable environment. Homology- Homology: similarity resulting from common ancestry- Many animals that have common ancestors result in having similar structureswhich are called homologous structures. Homologous structures represent variations on a structural theme that was present in their common ancestor. Example: human arm, cat leg, whale fin, and bats wing- Vestigial structures: are remnants of features that served a function in the organism’s ancestors. Example: post anal tail and pharyngeal pouches in botha chicken and human embryo.- Homologous characteristics form a nested pattern: all life shares the deepestlayer, and each successive smaller group adds its own homologies to those it shares with larger groups. - Evolutionary tree: a diagram that reflects evolutionary relationships among groups of organisms. - Convergent evolution: the independent evolution of similar features in different lineages. Example: flying squirrel and sugar gliders ability to glide- Analogous: share similar function but not common ancestry. Fossil Records- Fossil record documents the pattern of evolution, showing how past individuals differed from present day organisms. They also show evolutionary changes that have occurred in various groups. Example: the pelvic bone in fossil stickle back fish reduced in size over time in different lakes.Biogeography- Biogeography: the geographic distribution of species. Influenced by factors like the continental drift.- Pangea: The united all Earth’s masses in one large continent 250 million years ago. - Endemic: species of plants of animals that are not found anywhere else inthe worldII. Concept 23.1-23.4 & 24.1- Microevolution: the change in allele frequencies in a population over generations- Genetic variations: difference among individuals in the composition of their genes or other DNA segments. In genetic variation the phenotype does not matter. Without genetic variation, evolution cannot occur. - Characters that vary within a population may be discrete or quantitive. Discrete characteristics can be classified on an either or basis, they are determined by a single gene locus with different alleles that produce distinct phenotypes. Quantitative characters vary along a continuum within a population; usually result from the influence of two or more genes on a single phenotypic character. - Average heterozygosity: the average percent of loci that are heterozygous. To measure nucleotide variability biologist compare the DNA sequences of two individuals in a population and then average the data from many such comparison. - The nucleotide differences that provide the basis of genetic variation arise by mutation and other processes that produce new alleles and new genes. - New genetic variants are produced rapidly in organisms with short generation times. In sexually reproducing organisms, most of the genetic differences among individuals result from crossing over, the independent assortment of chromosomes, and fertilization. - Geographic variation: differences in the geographic composition of separate populations.- Cline: a graded change in a character along a geographic axis.- Population: a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring. Some populations can be geographically isolated from others, but most are not. A population’s genetic makeup is describes by its gene pool, which consists of copies of every type of allele at every locus in all members of population. Every allele has a frequency in the population.- Hardy-Weinberg principle states that frequencies of alleles and genotypes in a population will remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work. EQUATION:p2+ 2 pq+ q2=1 Changes occur in genotype frequencies when atleast one of the conditions of theHardy-Weinberg equilibrium is not met: 1. NO mutation2. Random mating3. No natural selection4. Extremely large population size5. No gene flow- In Natural selection the phenotype matters. Individuals in a population exhibit variations in their heritable traits, and those traits that are better suited to their environment tend to reproduce more offspring than those whose traits are not suited for the environment. It can cause adaptive evolution (evolution that results in a better match between organisms and their environment.)- In genetic drift, chance fluctuations in allele frequencies over generations tend toreduce genetic variation. Two examples are the founder effect and the bottleneckeffect. When a few individuals from a group become isolated, the smaller group may establish a new population whose gene pool