MACROEVO & FOSSIL RECORD

1. Microevolution

   Annotations:

   • changes in gene freq & traits that occur within populations and species = the study of Population genetics
2. Macroeolution

   Annotations:

   • evolution of large differences – above species level, warranting placement in a new genera or higher taxonomic group = the study of phylogenetics
   1. Clade level change
   2. Large‐scale patterns
      1. Origin of mammals
         1. e.g. Dinasours --> Birds

            Annotations:

            • Discovered in the 1970’s that Archeopteryx (originally found in 1860) was a transitional form between the Birds and Reptiles
            1. 1st evidence of feathers
      2. Radiation of flowering plants.(e.g. angiosperm)
         1. has been linked to the radiation of the major angiosperm pollinators

            Annotations:

            • radiation of angiosperm- also see radiation among other pollinator groups
   3. Macro' history is reconstructed from: geology, fossils and living organisms
      1. Mutation, gene flow, genetic drift & natural selection = MACRO
   4. 2 Principal phenomena to explain:
      1. 1. the evolutionary transitions that explain differences of major taxonomic ranks
         1. Fossil record
         2. Geology
      2. 2. the changes in distribution of taxa in time and space, especially over geologically significant timescales
         1. Biogeography
         2. Plate tectonics

Annotations:

• • Preserves traces of past life • Arbitrarily older than 10,000 yrs

1. TYPES
   1. Whole Organism
      1. e.g. bodies that are mummified in a very dry & cold climates
      2. enormously well preserved
      3. have a lot of taxonomic characters
   2. Trace fossils
      1. e.g. Carnivorous Dinosaur Coprollite (poop)
      2. e.g. Laetoli Hominid footprints 3.5Mya
      3. imprint
   3. Microfossils
      1. plant /animal fossil <1mm
   4. Resinfossils
      1. Fossil within a fossil
   5. Pseudofossils
      1. inorganic objects, markings, or impressions that might be mistaken for fossils
         1. e.g. manganese dendrites, moss agate
      2. Rock fissures are filled up with percolating minerals (geologic rather than biological process)
   6. Living fossils
      1. Major constituent of the fossil record for the first 3.5 billion yrs
      2. e.g. Stromatolites, Shark Bay
         1. formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms, especially blue‐green algae
      3. e.g. Coelacanth - Latimeria chalumnae (fish)

         Annotations:

         • Originally thought to have been extinct since the end of the cretaceous (65 Mya)
      4. e.g. Gingko Biloba (plant)

         Annotations:

         • Dates back in the fossil record to 270 Mya 5‐2 Mya disappeared from the fossil record everywhere except small area in central China
2. Fossilisation process

   Annotations:

   • Organism must be buried before complete decay, erosion or consump-on by a scavenger
   1. Formation types
      1. Compression, casts & moulds, permineralisation, unaltered remains
   2. dependent on:
      1. • Durability (hard vs soft) • Burial (saturated sediment) • Lack of oxygen
   3. ultimately - need to form ROCK
3. How good is it?
   1. ± 250 000 described fossils (not a lot)
   2. Lineages are separated by long periods of time
   3. Gaps of many thousand years
   4. Fossil species are only known from a few specimens
4. Bias
   1. Geographic (sampler and habitat)

      Annotations:

      • Any sort of preservation dependent on location relative to lowland and marine habitat. The animal/plant has to have the opportunity to be covered by sediment
   2. Taxonomic

      Annotations:

      • - Marine organisms dominate the fossil record BUT make up only 10% of extant species - 2/3rds of all animal phyla underrepresented as do not have mineralised hard parts - Soft reproductive structures of plants (flowers) not generally preserved
   3. Temporal

      Annotations:

      • - The Earth’s crust is being constantly recycled - Both tectonic activity and erosion of rock surfaces has/will lead to the loss of fossils
5. Rock Strata
   1. Rocks arranged in a predictable pattern with strata found in the same relative position
   2. Assemblages of fossils from older to younger rocks
   3. Layers of sediment contain distinctive suites of fossils
   4. Radiometric dating provides a time sequence
   5. Fossil record provides evidence of changes that have occurred in the history of life

1. Paleography
   1. continental drift
2. Wallace – studied animal distributions whilst collecting specimens in Asia and Indonesia
   1. Discovered different suites of species on different islands with the same climate
   2. Darwin and Wallace believed the only plausible explanation – Natural selection
3. Biogeography – similarities and differences between geographic regions
4. Drivers of biogeographic distribution

   Annotations:

   • All drive macroevolutionary patterns of species distribution
   1. 1. Movement of the landmasses and formation of continents
   2. 2. Formation of land-bridges
   3. 3. Sea‐level change
   4. 4. Climate