Zusammenfassung der Ressource
MACROEVO & FOSSIL RECORD
- OPERATES AT DIFF SCALES
- Microevolution
Anmerkungen:
- changes in gene freq & traits that
occur within populations and species = the study of Population genetics
- Macroeolution
Anmerkungen:
- evolution of large differences
– above species level, warranting placement in
a new genera or higher taxonomic group = the
study of phylogenetics
- Clade level change
- Large‐scale patterns
- Origin of mammals
- e.g. Dinasours --> Birds
Anmerkungen:
- Discovered in the 1970’s that Archeopteryx (originally found in 1860) was a transitional form between the Birds and Reptiles
- 1st evidence of feathers
- Radiation of
flowering plants.(e.g. angiosperm)
- has been linked to
the radiation of the
major angiosperm
pollinators
Anmerkungen:
- radiation of angiosperm- also see radiation among other pollinator groups
- Macro' history is
reconstructed from: geology,
fossils and living organisms
- Mutation, gene flow,
genetic drift & natural
selection = MACRO
- 2 Principal phenomena to explain:
- 1. the evolutionary transitions that
explain differences of major taxonomic
ranks
- Fossil record
- Geology
- 2. the changes in distribution
of taxa in time and space,
especially over geologically
significant timescales
- Biogeography
- Plate tectonics
- THE FOSSIL RECORD
Anmerkungen:
- • Preserves traces of
past life
• Arbitrarily older
than 10,000 yrs
- TYPES
- Whole Organism
- e.g. bodies that are
mummified in a very dry &
cold climates
- enormously
well preserved
- have a lot of taxonomic
characters
- Trace fossils
- e.g. Carnivorous Dinosaur
Coprollite (poop)
- e.g. Laetoli Hominid
footprints 3.5Mya
- imprint
- Microfossils
- plant /animal fossil <1mm
- Resinfossils
- Fossil within a fossil
- Pseudofossils
- inorganic objects,
markings, or
impressions that might
be mistaken for fossils
- e.g. manganese dendrites, moss agate
- Rock fissures are filled up with
percolating minerals (geologic
rather than biological process)
- Living fossils
- Major constituent
of the fossil
record for the
first 3.5 billion yrs
- e.g. Stromatolites, Shark Bay
- formed in shallow water by the
trapping, binding and cementation of
sedimentary grains by biofilms of
microorganisms, especially
blue‐green algae
- e.g. Coelacanth - Latimeria
chalumnae (fish)
Anmerkungen:
- Originally thought to have been extinct since the end of the
cretaceous (65 Mya)
- e.g. Gingko Biloba (plant)
Anmerkungen:
- Dates back in the fossil record to 270 Mya
5‐2 Mya disappeared from the fossil record
everywhere except small area in central China
- Fossilisation process
Anmerkungen:
- Organism must be buried
before complete decay, erosion
or consump-on by a scavenger
- Formation types
- Compression, casts
& moulds,
permineralisation,
unaltered remains
- dependent on:
- • Durability (hard vs soft) •
Burial (saturated sediment)
• Lack of oxygen
- ultimately - need to
form ROCK
- How good is it?
- ± 250 000 described
fossils (not a lot)
- Lineages are
separated by long
periods of time
- Gaps of many thousand years
- Fossil species are
only known from a
few specimens
- Bias
- Geographic
(sampler
and habitat)
Anmerkungen:
- 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
- Taxonomic
Anmerkungen:
- - 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
- Temporal
Anmerkungen:
- - The Earth’s crust is being constantly recycled
- Both tectonic activity and erosion of rock surfaces has/will lead to the loss of fossils
- Rock Strata
- Rocks arranged in
a predictable
pattern with strata
found in the same
relative position
- Assemblages of
fossils from older to
younger rocks
- Layers of sediment
contain distinctive suites
of fossils
- Radiometric
dating provides a
time sequence
- Fossil record provides
evidence of changes
that have occurred in
the history of life
- BIOGEOGRAPHY \ PLATE TECTONICS
- Paleography
- continental drift
- Wallace – studied animal
distributions whilst collecting
specimens in Asia and Indonesia
- Discovered different
suites of species on
different islands with the
same climate
- Darwin and Wallace believed
the only plausible explanation –
Natural selection
- Biogeography – similarities and
differences between geographic
regions
- Drivers of biogeographic distribution
Anmerkungen:
- All drive macroevolutionary patterns of species
distribution
- 1. Movement of the
landmasses and formation of
continents
- 2. Formation of land-bridges
- 3. Sea‐level change
- 4. Climate