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Chapter 10: Evolution the Evidence (Recent evolutionary Change (Antibiotic…

- - - - Palaeontology involves the study of ancient life represented by fossils
      - Fossil record refers to the total number of fossils that have been discovered, providing evidence of the evolution of living organisms through geological time.
      - Fossils inform palaeontologist about ancient life, what they looked like and where and when they lived. It allows scientist to put a time scale on evolution
      - Fossilisation
        
        It is the preservation of the hardened remains or traces of organisms
        
        soft bodied animals are unlikely to be preserved
        
        fossilisation occurs often when organism is buried by sediments which reduces the chance of decay due to lack of oxygen
        
        ex of sedimentary rock are sandstone, stiltstone, mudstone and shale
        
        Organism on land are less likely to be preserved than those that are aquatic because there's a less likely chance that organisms that die on land are going to be covered up by sediments
      - Types of fossils
        
        Impression fossils
        
        impression fossils are left when entire organism decays but the shape or impression of the external; or internal; surface remains
        
        Mineralised fossils
        
        Occurs when minerals replace the spaces of structures of organisms such as bones
        
        mineralisation or petrification
        
        Trace fossils
        
        are the preserved evidence of an animal's activity or behaviour, without containing parts of the organism.
        
        ex: footprints, casts of burrows, coprolites
        
        Mummified fossils
        
        those have been trapped in a substance under conditions that reduce decay and so undergo little change
      - Dating fossil
        
        gives us the time scale of evolution
        
        can be determined through
        
        absolute dating
        
        provides a more precise estimate of age, although it does not mean that it provides an exact date. Methods of absolute dating that are used to determine age of fossils
        
        Radiometric dating
        
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        thermoluminescence
        
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        Electron spin resonance
        
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        relative dating
        
        based on stratigraphy which is the study of the relative positions of the rock strata, or layers, some which contain fossils
        
        lowest is oldest, upper strata are progressively younger
        
        can be difficult in areas where rock layers have been eroded, or where rocks have been buckled, moved or reburied, altering the original sequence of strata
        
        index fossil is a fossil used to define and identify geological periods
      - other information can be gained or inferred from examining fossils apart from indicating the appearance and structure of an organism.
    - - comparing structures of organisms is referred to as comparative anatomy
      - morphology of species, or their body structures,gives an insight into the relationships between species
      - Homologous features
        
        same structure but different function
        
        tells us that the organisms may be from the same ancestor
      - Vestigial structure
        
        structure that an organism obtain but is no longer is used but have been to their ancestor
      - Analogous features
        
        Show similarity that is not due to common ancestry, ex flying animals such as butterfiles and birds have wings
      - Comparative embryology
        
        comparing zygote and embryo in the study of evolutionary relationships
    - - techniques were available, structural and functional similarities were the main evidence used to determine relatedness.
      - Determining relatedness between species using molecules
        
        similar chromosome or DNA sequences
        
        time passes causing sequences of nucleotides in their DNA becomes more different and what was once similar DNA dicerges
        
        Changes in DNA are due to mutation
        
        sometimes errors are repaired but of not, it become permanent part of the genome
      - Amino acids and acid sequence
      - Molecular clocks
      - Phylogenetic trees
- - - - Wherever the region that cane toads arrive, it had led to the decline of animals in that particular region as cane toads appears to be a threat for them
        
        These includes birds and snakes
        
        However organisms from the region have evolved to adapt to their current environment
        
        For example, through natural selection, snakes that have smaller heads were able to survive better as they eat smaller toads that contain fewer toxin
  - - - Divergent evolution occurred causing now there to be two different species of mosquitoes