Darwin

Darwin

1. Origins of Species Concepts

   • 1. all organisms produce more offspring than could survive e.g. tadpoles
   • 2. population of a species remains fairly constant over time
   • 3. all species have a wide variation within their characteristics
   • 4. some characteristics are inherited and passed down
   • 5. Natural Selection is determined by survival of the fittest

2. Biological Theory of Evolution

   • Origins of Life Theories
     • Special Creation
       • Intellgient desgin
       • All beings created purposefully by an intelligent designer
     • Spontaneous Creation
       • After Big Bang atmosphere was very crude
       • This gave way to chemical reactions which formed proteins
       • proteins = simple life
     • Aristolean View (Steady State)
       • All things are as they were and always will be
   • Lamarck
     • those who desire change will change
     • parent always passes favourable traits onto offspring
       • HOWEVER this is incorrect obviously due to genetics and was disproven by Weismann
       • GIRAFFE!
   • Weismann
     • Disproved Lamarck
       • Cut off mices tails and produced offpspring who had tails = parents did not pass on desirable traits ALWAYS
   • Adaptions
     • Physical
       • Behavourial
         • (instinctive)
         • Fuctional
           • (metabolical)
   • Variation is caused by...
     • mutations
     • sexual reproduction
     • crossing over (mitosis 1)
   • Evidence for Evolution
     • transitional life form
       • A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group
     • Fossils
       • The oldest rocks contain fossils of simple, primitive organisms
       • Younger rocks contain fossils of more advanced life forms
       • through geology, the time of the species existance can be placed
       • Making Fossils
         • Most found in sedimentary rock
           • sedimentary rock : rock formed under a body of water
             • this is because they are formed at temperatures that do not destroy remains
         • must be quickly covered and compressed = protected
           • soft bodied organisms only preserved if compressed and burial = quick
       • Homid Fossils
         • fossil that appear to be ancestors of humans
       • Dating Fossils
         • radioactive elements decay exponentially over time
         • igneous rocks
           • rocks formed after the cooling of lava
         • Radiometric Dating Method
           • the estimation of the age of igneous rocks
         • Radiocarbon Dating Method
           • The estimation of the age of a fossil by studying the amount of carbon
     • Comparative Embryology
       • The study of the similarities and differences between various species' embryos.
       • evidence for evolution because similarities = similar genes
         • vertebraic animals have common features = gills and tails
           • evidence for common ancestor
     • Homologous Structures
       • Structures that are likely to have had a common ancestor
         • They have similar structure
         • but different function
       • pentadactyl limb
         • A limb that has five phalanges and a set structure of a radius, ulna, humerus, and carpals
     • Vestigial Organs
       • Organs that have become nonfunctional in a species
         • e.g tailbones in humans
       • once useful which indicates that organisms must have had different structures and functions before the present
     • Biochemical Evidence
       • DNA and RNA are made from the same nucleotides in all organisms
         • = same proteins being made
       • Cytochrome-C
         • protein involved in cellular respiration
         • number of differences in amino acid sequence = further species are evolutionarily separte
       • Blood Protein
         • DNA protein molecules slowly become different after species divergence
         • number of difference = proportional to time species has been separate
     • Relative Dating
       • sequential order of strata (rock layers)
         • strata are internationally realtive
           • new fossil types mark changes in the environment
   • Evolution and Continental Drift
     • Pangaea the supercontinent split up 1.2 mil ya
     • Movement of Tectonic Plates
       • Convenction currents underneath the earth's crust cause movement
       • This shift causes the formation of mountains, trenches, valleys etc.
         • Fossils can be metled in this process in the subduction zone = under the crust
     • Plant and animals groups dispersed very different environments as a result.
       • Adaptions to new environments have arisen as a result of Natural Selection
   • Isolating Mechanisms
     • Allopatric Speciation
       • divergence of a new species after common ancestor has been subdivided through geographical isolation
         • 1. movement into new environments
           • 2. Geographical isolation
             • 3. Different selection pressures
               • 4. Reproductive isolation
     • Prezygotic Isolation
       • Temporal Isolation
         • Different breeding seasons, active during different times
       • Gamete Isolation
         • Gametes are incompatible
           • sperm may not survive reproductive tract
       • Behavioral Isolation
         • differences in courtship
       • Morphological Isolation
         • differences in structure
           • anatomy prevents sperm transfer between organisms
     • Post Zygotic Isolation
       • Hybrid Sterilization
         • Hybrid produced will be infertile
       • Hybrid inviability
         • Hybrid zygote cannot develop
       • Hybrid Breakdown
         • Hybrid is created but is dysfunctional and weak
           • second generation cannot survive

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