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Evolution
| Question | Answer |
|---|---|
| macroevolution | current species are descendants from ancestral species, which were different from the current ones. Can happen quickly; just involves emergence of new, unique species (depends on which genes are affected) |
| microevolution | a change in the genetic composition of a population from one generation to the next |
| what is the key requirement for evolution? | genetic variation |
| adaptation and evolution are the same. (True/False) | false |
| compare/contrast adaptation & evolution | adaptation: heritable trait that helps an organism's survival & reproduction in present environment; evolution: change in the genetic structure of the population over time, adaptations may lead to evolution |
| what is the unit of evolution? | population. populations evolve, organisms live and die |
| define evolution | the change in the genetic structure of a population over time |
| name the mechanisms of evolution | gene flow, genetic drift, natural selection |
| main features of natural selection | it is not random (the environment directs it); it leads to adaptation (the environment selects the best suited traits); it is dynamic (changes in the environment lead to new selection criteria); only populations evolve, not individuals |
| types of natural selection | directional selection. disruptive selection, stabilizing selection |
| define natural selection & describe: the accumulation of traits & source of traits | the accumulation of favourable traits within a population. many traits could be favourable in the environment (accumulation); not individual - population is unit of evolution; heritable, favourable traits already exist within the population |
| criteria for explaining natural selection | organisms vary in heritable characteristics; populations reproduce more than environment supports; well suited organisms live & reproduce more; over time, favourable traits accumulate, changing genetic structure of population |
| describe directional selection & give example | population characteristics shift towards one side of trait spectrum. ex. in environment with dark rocks, mice with darker fur are better protected |
| describe disruptive selection & give example | population characteristics shift towards extremes of trait spectrum. ex. in environment with light and dark rocks, mice of dark or light fur are better protected |
| describe stabilizing selection & give example | population characteristics shift towards intermediacy of trait spectrum. ex. in environment with rocks of intermediate colours, mice of intermediate fur colour are better protected |
| what do you need to specify during natural selection? | it happened in a population with genetic variation & favourable traits were already present in the genome but weren't advantageous until now |
| define gene flow & give example | the movement of alleles among populations through the movement of fertile individuals or gametes ex. blue jays carrying and dropping acorns (seeds) from one oak tree population to another |
| define genetic drift & give example | random events (often disasters) that drastically change the frequency of alleles in small populations ex. bottleneck effect - disaster kills off majority of a population and eliminates uncommon genes by chance |
| name the direct observations of evolutionary change | fossil record, homologies (anatomical, embryonic, vestigial organs, molecular), analogies (convergent evolution), biogeography |
| evolution is a theory. (True/False) | true |
| contrast homologies & analogies | homologies: shared ancestry (divergent evolution), similar structures that can have different functions; analogies: guided by environment (convergent evolution), similar functioning structures that evolved independently from different lineages |
| describe fossils as evidence for evolution | preserved remnants or impressions left by organisms that lived in the past. provide evidence of change by comparing older to newer fossils to existant species |
| describe anatomical homologies as evidence for evolution | structural similarities in organs/tissues with different functions, ex. organization of arm bones between humans, cats, whales & bats |
| describe embryonic anatomical homologies as evidence for evolution | similar embryonic structures have different development fates, ex. pharyngeal pouches in chick & human embryos |
| describe vestigial organs as evidence for evolution | remnants of organs that served a function in an organism's ancestors are still present, without a function ex. human coccyx (tail bone) |
| describe molecular homologies as evidence for evolution | similarities in the biochemical composition of proteins between related species - longer two species evolving on their own, greater the # of genetic differences. ex. humans share over 90% of their DNA with apes. |
| describe anatomical analogies as evidence for evolution | the body shapes of animals with similar lifestyles are similar even if they have different ancestors. ex. insect, bird & bat wings |
| describe biogeography as evidence for evolution | evolution occurring at different times in relation to the movement of geological tectonic plates. ex. ancestors of groups that were on ancient supercontinent Pangea are distributed worldwide, islands have endemic species due to isolation of inhabits |
| sources of genetic variation | meiosis, fertilization, mutations |
| mutation | random change in DNA at any time (can be good, bad or neutral and range of less to greater effects); only source of new genetic variation; could happen during formation of gametes, meiosis, or later in organism's life; rate of mutation can change |
| define adaptation | a heritable trait that helps an organism's survival and reproduction in its present environment over time |
| describe meiosis | a process of cell division that produces haploid & genetically diverse gametes (sperm cells & eggs) |
| function of fertilization | vary offspring; fertilization brings together gametes with diverse genetic backgrounds (genes with different alleles) |
| describe regulatory genes & their significance | genes that regulate the coding of other genes; significant for macroevolution: the mutation/change of a regulatory gene will have a greater effect on the population than lesser genes |
| describe how drug resistance in microbes supports natural selection | a certain species of bacteria, originally not known to be resistant to a certain antibiotic, can become resistant through repeated exposure to that antibiotic; supports genetic variation |
Created by:
AntBanana
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