09 04 2014 Bio Lecture week of 9 2 Readings Chapters 1 20 21 Important terms often misused Fact a well confirmed observation o Lots of independent evidence o Unlikely to be overturned o NOT proof or truth Law general statement describing some aspect of the natural world and how it behaves o Not known to vary Hypothesis possible tentative explanation of observations o May be weakly supported well supported or not supported Theory very well supported explanation o Relies on facts laws hypotheses o Supported by lots of observations o Tested in many different ways and circumstances Facts Laws require explanations Hypotheses Theories provide explanations Biology The study of life science of living things What is living o Made up of one or more cells basic unit of life o All use energy Can make own Autotrophs plants Take from others Heterotrophs o Maintain homeostasis consistent internal conditions o Ability to reproduce grow develop o Respond to environment external internal stimuli o Possess life cycle o Adapt evolve relative to environment Short and long time scale o Respiration maintains metabolism o Highly ordered but complex Hierarchy to life Atoms Molecule Macromolecule Organelle Cell Tissue Organ Organ System Organism Population Species Community Ecosystem Biosphere Earth Evolution Change over time Within biology evolution has a dual nature o Can be FACT observations data of change over time in living organisms Well confirmed Living things change over time o Can be THEORY explanation Change of living things over time over a long time has generated diversity of life we see around us today First mechanism of evolution o Natural Selection not published until 1859 when Darwin published On the Origin of Species Published because Wallace reached out to Darwin w same ideas o Darwin Wallace Theory of Evolution by Natural Selection Alfred Russel Wallace o Where did Darwin s ideas come from Served 5 year voyage on HMS Beagle Pivotal events on voyage Realized Earth was much older than thought Read Principles of Geology Charles Lyell Recognized there was enough time for natural selection to occur Fossils resemble modern organisms currently living species Recognized potential for shared ancestry relatedness Similar species varied from place to place in ways that suited their environment Could mean that organismal change from some common ancestor could be affected by environment After voyage Even though organisms of same species look similar they re not identical Always slight variations in morphological characteristics features of all creatures 4 Postulates ideas Darwin used to lay out evolution by natural selection 1 Individuals within species are variable variation may have no impact on organism could be advantageous or disadvantageous but sometimes variation results in an individual having an advantage o can lead to increased survival and or increased reproduction 2 Some of an individual s variation is passed on to its offspring variation is heritable 3 In every generation more offspring are produced than can survive struggle for existence survival 4 Offspring that survive AND reproduce may have inherited variation that gives them an advantage Such as long legs for quickness Fitness index of reproductive success o Increases with increased reproductive output Important that they survive and reproduce o Fitness 0 if no offspring produced o Survival of the fittest If same struggle to survive and reproduce continues over thousands of years then each successive generation of beetles will be slightly quicker long legged o New species can occur speciation Evolution by Natural Selection one mechanism by which evolution occurs Requires that variation is adaptive and results in selection for against certain organisms 1 Variation must exist for a given trait o Without variation selection doesn t affect survival in any way All individuals will respond the same to a given selective There are no advantages to be passed on to future pressure generations 2 Variation must lead to differential survival reproductive success fitness o Food availability can drive natural selection o Medium ground finch has variability in its beak bill characteristics 3 Variation must be heritable o Can be passed onto offspring Lamarck proposed idea of evolution by acquired inheritance variation o Trait variation passed to offspring was based on use disuse by o Doesn t make sense though ruled out o Ex Giraffes keep stretching neck so eventually they all parents became longer 09 04 2014 09 04 2014
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