Evolution Latest 2023 with Complete and Certified Solutions

Evolution Latest 2023 with Complete and Certified Solutions Evolution The theory that organisms change over time. It is the process by which modern organisms have descended from ancient organisms. Natural Selection The process by which organisms succeed in an environment in order to reproduce and pass on their traits to their offspring. Results in adaptations to environmental conditions. "Survival of the fittest". Occurs when Individuals differ, variation can be inherited, or inherited differences affect reproduction. Happens through sexual selection, competition, and predation. Evidence for Evolution Fossil Records Biogeography Homologous Structures Vestigial Structures DNA Sequencing Development Similarities Fossil Records Refers to the order in which fossils appear within the Earth's rock layers. Biogeography The study of the distribution of plants and animals in habitats around the world. Homologous Structure Similar internal structures that have different functions in organisms (forelimbs of penguins, human, crocodile, bat. This is an anatomical homologies. Vestigial Structures Structures that serve little or no useful purpose in an organism. Because they have no major purpose in the modern organism, their presence indicates structural change over time. DNA Sequencing Supports evolution by offering evidence of a common ancestor. Development Similarities Comparisons of how organisms develop. Similarities in early development to support descent from a common ancestor. Fitness An organism's reproductive success. Organisms with greater fitness reproduce and pass on their traits to their offspring. Adaptation The process by which a population becomes better suited to its environment. Artificial Selection (Selective Breeding) Humans can affect the frequency of alleles in a population's gene pool by intentional selecting for certain traits. Examples are agriculture and dogs. Mutation A change in DNA. Are random events that may be helpful, harmful or neutral. *Not all mutations affect offspring.* Germ-line Mutation Only mutation in the gametes of an organism get passed on to offspring. This affects evolution. Genetic Recombination (Crossing Over) A process that produces different combinations of genes from the parents to the offspring. Occurs during meiosis. Gene Pool Consists of allele frequencies that can change randomly through generations due to change. Founder effect (Example of Genetic Drift) Occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have: reduced genetic variation from the original population or a non-random sample of the genes in the original population. Bottleneck Effect (Example of Genetic Drift) Occurs when there is a drastic reduction in the genes of a population's gene pool as a result of an environmental or human-cause change. The reduction of genes limits variation within that population. Example: Humans hunted the N. Elephant Seal to near-extinction (only 20-30 in the entire population) in the 1890s. the small population had very limited genes within the gene-pool, so when they began repopulating, there was (and still is) less genetic diversity in their population. Gene Flow The transfer of alleles from one population to another; it can happen as a result of migration or seed transfer. Stabilizing Selection Selective pressures select against the 2 extremes of a trait, thus selecting the intermediate trait; favors the "medium" trait. Example: A plant that is too short may not be able to compete with other plants for sunlight. Extremely tall plants may be more susceptible to wind damage. This causes a shift in plant-height--combined, thee 2 selection pressures selected medium-height plants. Directional Selection One extreme of the trait experiences selections against it, and the population shirfts toward the other extreme trait; favors one extreme or the other. Example: There was election pressure against short necks in giraffes, since short-necked giraffes couldn't reach as many leaves to feed. As a result, neck length shifted to favor giraffes with longer necks. Diversifying Selection Also called disruptive selection; selective pressures act against intermediate individuals ("medium" trait), thus selecting both extreme traits; favors both extremes. Example: Birds preferred medium-sized insects for their meal. The population of insects shifted and selection produced only very large and very small insects. Millions ________ of species alive today are only a small fraction of all species that ever existed. Fossils records reveal that about 99% of ancient species are extinct Fossils Relics or impressions of ancient organisms and include skeletons, shells, seeds, insects trapped in amber, imprints of organisms, organisms frozen in ice (woolly mammoth), or trapped in tar pits (saber-toothed tiger). They provide a record of biodiversity, behavior, and environment of ancient life on Earth. They provide evidence of how organisms have gradually changed or evolved over time. Analogous structures Structure that are similar in function. but not in structural appearance (both birds and butterflies have wings to fly, but both look very different) Anatomical homologies Similarities in the embryo Stages of development in fish, reptiles, birds and mammals. Developmental homologies. Biochemical Similarities The DNA of different species in the best way to establish relationship. Molecular homologies Physical Distribution Factors, such as location of continents, determine where a species can spread (marsupials in Australia). Also known as biogeography. Tools To show relationships with modern organisms to those of the past. Cladograms Shows relatedness based on "derived characteristics" appearing in later organisms and not in earlier organisms; organisms "branch off" the diagram because they no longer share a similar characteristic. Phylogenetic Trees Shows relatedness across groups of organisms based on similarities and differences in physical and/or genetic characteristics; useful in illustrating common ancestor-show evolutionary timeline. homologous structure an anatomical structure found in different species that shows