APS121 Evolution - Wellman Flashcards
Neo-Darwinian theory can be summarized in six propositions. What are they?
- Reproduction
- Excess
- Variation
- Selection
- Divergence
- Ancestry (all share 1 common ancestor)
What is taxonomy?
The science of classification of organisms
What is phylogeny?
The study of evolutionary relationships
How old is the earth?
4.6 billion years old
The fossil record is incomplete and highly biased. How is it incomplete?
- Very few organisms that ever live end up fossilised (even ewer collected and studied)
- Entire species or higher taxa may not be preserved. Perhaps due to low preservation potential, small population, small geographic area, short period of existence
How is the fossil record biased?
- Certain environments more likely to be preserved than others (net deposition over erosion - e.g. marine organisms more likely to be preserved)
- Organisms with more hard and readily preserved tissues are more likely to preserved (bone, tooth, shell, wood etc.)
Give some examples of environmental change through time
- Solar luminosity
- Distance between earth and moon (tides)
- Continental drift
- Changing atmosphere and climate change
- Milankovitch cycles (around sun)
- The evolving biota
- Rare events (Tsunamis, supereruptions, meteorite impacts, mass extinctions)
What is the order of taxonomic groups?
Kingdom Phylum Class Order Family Genus species
What is cladistics?
- The most widely used method of determining phylogeny nowadays
- Based on evolutionary relationships - classifies species according o how recently they share a common ancestor
- assumes life only evolved once and diversity originated through descent with modification
- reconstruct phylogeny through formal character analysis (only presence of homologous characters is used)
- illustrated using diagrams called cladograms
What are symplesiomorphies?
Shared ancestral characters
What are synapomorphies?
Shared derived characters - used to work out phylogenetic relationships
What are autapomorphies?
Characters unique to one species or group - used to define taxonomic groups
What are monophyletic groups?
Contain latest common ancestor plus ALL its descendants - used for cladistics
What are paraphyletic groups?
Not including all descendants of common ancestor (part of monophyletic group removed or missing) - meaningless for cladistics
What are polyphyletic groups?
Most recent common ancestor assigned to some other group and not the group itself - defined on the basis of convergence, or non-homologous characters assumed to have been absent in the latest common ancestor - meaningless for cladistics
What are the three domains?
Archaea, bacteria, eukarya
What are the five kingdoms?
Monera, Protista, Animalia, Fungi, Plantae
How big do prokaryotic cells tend to be as opposed to eukaryotic?
Prokaryotic: 1-10 micrometres
Eukaryotic: 10-100 micrometres
what are flagella made of in prokaryotes?
Flagellin
How do prokaryotes reproduce?
Binary fission - tend to be asexual but some parasexual
Where do the less numerous and diverse archaebacteria inhabit?
Extreme environments (e.g. thermophiles, halophiles)
How was the earth formed 4.6 billion years ago?
Gravitational accumulation of dust and larger objects. Mass melts and differentiates into core, mantle and crust (iron and nickel migrate to centre, silica and aluminium minerals form crust).
+ moon forms during major collision
What is the age of the oldest rocks on earth?
- 75 billion years old (when crust began to solidify)
- oceans and atmosphere partially begin to condense out
Why was the progress of the development of the Earth retarded >3.8 billion years ago?
Continuous bombardment of large objects - with released energy sufficient to boil of the oceans and atmosphere (along with any prebiotic components)
- active with plate tectonics and weathering and erosion
<3.8 billion years ago, when meteorite bombardment decreased in intensity, the planet cooled below a threshold that allowed oceans and atmosphere to condense out. What did this allow?
Organic compounds to begin to be synthesised and accumulate
When is the earliest fossil evidence for life on earth?
3.5 billion years ago
What is the panspermia theory?
Life (or its precursor) was delivered to earth by a comet from elsewhere in outer space