Lamarck's ideas about evolution, proposed evolution, NOT correct in his ideas of HOW it occurred, acquire/gain OR lose a trait in ONE lifetime --> trait inherited by offspring, Darwin's ideas about evolution , believed evolution, variation w/in the a population, those w/ the best adaptations are chosen by nature (natural selection) for survival & reproduce, individuals w/o adaptation will struggle and die, Scientists' ideas about evolution today, believed in evolution, AGREE W/ DARWIN!!, known sources of variation w/in a population --> 1 = random mutations (cannot mutate @ will to survive) and 2 = (only sexually reproducing population) gene shuffling, Adaptation, inherited traits that increase survival chance, Adaptation sources, Random mutations --> due to radiation, pollution, mistakes in DNA replication, viruses, etc. --> occur in BOTH asexually/sexually reproducing species; events specific to sexual reproduction = crossing over of homologous chroms. (meiosis), independent assortment of chroms (meiosis), + random fertilization, Artificial selection, human choice!! cause: humans, speed of change: fast, reason for occurrence: trait is desirable for human breeders, effect on fitness: often decreases, Natural selection , environmental change/disease! cause: environment, speed of change: slow, reason for occurrence: selected trait increases organisms' chances of survival/reproduction, effect on fitness: increased fitness, Speciation, formation of a NEW species b/c of reproductive isolation, Why does speciation occur?, Genetic variations chosen for survival in each isolated population are SO DIFFERENT that many years later when the pop. are reintroduced, they can't interbreed to make fertile offspring, Reproductive isolation, groups of individuals form the SAME original pop. can no longer interbreed & produce fertile offspring , Causes of reproductive isolation, physical barriers, behavior/mating behavior, mechanical (sex organs too diff. to mate), physiological (hybrid offspring have lower survival fitness than pure offspring), Coevolution, 2 species evolve in response to changes in each other's adaptions --> ex. flower + pollinator (mutualism), predator + prey, OR plant + herbivore, Adaptive radiation, a single ancestral species gives rise to a variety of species w/ unique adaptations to diff. environments --> speciation can be rapid as new habitats become available--> ex. Darwin's finches, Gene pools, combined genetic info of all members of an interbreeding poplulation, Relative frequency, # of times an allele occurs in a gene pool compared w/ the # of times other alleles occur (%), **Sources of genetic variation, 1: mutations - occur randomly in BOTH asexually/sexually reproducing species; 2: gene shuffling - in sexually reproducing species --> crossing over of homologous chroms. (meiosis) + independent assortment of genes for diff traits on diff chroms. into gametes in unique combos (meiosis), Single gene trait, controlled by one gene w/ 2 alleles. variation only --> 2 possible phenotypes --> ex. peppered moths, Stabilizing selection, avg. form of a trait is favored, Directional selection, ONE extreme form of a trait is favored, Disruptive selection, either/both extremes are favored over the avg. form, Genetic drift, random changes in allele frequencies in SMALL POPULATIONS b/c of certain individuals, leaving more descendants by change --> increases allele in pop., Founder effect, a few individuals of a pop. are isolated & establish a new pop. w/ a gene pool that's NOT reflective of original pop. --> ex. Amish community, Bottleneck effect, a sudden environmental change decreases the pop. size drastically --> the few survivors have a gene pool that no longer reflect the original pop. --> ex. cause = natural disaster , Homologous structures, evidence for evolution; body structures are anatomically similar and are inherited from a COMMON ancestor, but FUNCTION DIFFERENTLY, Analogous structures, evidence for evolution; body structures serve the SAME FUNCTION but are NOT from a common ancestor & are constructed differently, convergent evolution, 2 unrelated species have SIMILAR ADAPTATIONS to the same environment, divergent evolution, organisms w/ common ancestry have DIFFERENT ADAPTATIONS selected by nature for survival, Comparative cytology, all living things are made up of one or more CELLS that have SIMILAR structures & organelles (ex. cell membrane, cytoplasm, DNA, ribosomes), Comparative embryology, structural and developmental similarities in embryos of diff species proves evidence of COMMON ancestry, Comparative biochem, DNA, RNA --> ATCGU, 20 types of amino acids, carbs, lipids --> all suggest common ancestry, Vestigial structures, organs/structures that no longer serve a function --> they're remnants of structures that functioned in an ancestral species --> their presence may mot affect survival, so natural selection has NOT eliminated them --> suggests structure & function can change over time (not common ancestry) , Fossil Record, remnants/traces of organisms that lived in the past, show a record of biological history & changes in biotic factors over time, phylogeny, the evolutionary history of a species/ related group of species --> constructed using evidence from morphological/structural evidence + **molecular evidence, morphological data, collected from physical/structural similarities b/w living and/or fossil species --> ex. microscopic stem structure (organization of veins), color of petals/fur/hair/feathers, size/shape of seeds/body parts, #/location of appendages, **molecular data, collected from analysis of DNA/RNA and amino acids sequences in proteins (BEST EVIDENCE TO USE) --> ex. nucleotide sequences w/in DNA, amino acid sequences w/in proteins, types of enzymes w/in cells, Ways to obtain molecular data, chromatography (separation of pigments of various widths), gel electrophoresis (separation of DNA fragments by size), cladogram, depicts patterns of shared characteristics among groups and forms the basis of a phylogenetic tree, phylogenetic tree, shows relationships b/w lineages (like cladogram) but also shows the amount of change over time determined by the use of fossil evidence, morphology, & molecular data, Evolution of DNA/RNA (RNA World Hypothesis), theory that the first genes were RNA and served to store genetic info & direct protein synthesis, Endosymbiotic theory, prokaryotic cells engulfed other prokaryotic cells by endocytosis, & this resulted in the 1st eukaryotic cells.

Evolution Test Review

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