Please enable JavaScript.
Coggle requires JavaScript to display documents.
The history of life/tree of life (phylogeny and the tree of life (How…
The history of life/tree of life
History of life on earth
conditions of early earth
5 mass extintions, the 2 major ones the permain, and the cretaceous
The geologic record
Cenozoic- 66 million years ago to present day
mesozoic- 252-66 million years ago
paleozioc- 541-252 million years ago
neo-proterzoic- 2500-541 million years ago
Archaen & haden- 4600-2500 million years ago
fossils
Fossils have ambiguities
Only hard parts make good fossils, for example a jelly fish will not make a good fossil
Not all animals die in areas where fossil formation is possible
Fossils are very hard to find and will never be complete
Fossils only show us to much about the shape, however we do not know how these species behaved.
Icecores- sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper, and an ice core contains ice formed over a range of years. Only go back 1.5 millions years
Fossil records show how new groups of organisms can arise via the gradual modification of preexisting organisms
key events
4 stages that led to first life
The abiotic (nonliving) synthesis o small organic molecules, such as amino acids and nitrogen bases.
The joining of these small molecules into macromolecules, such as proteins and nucleic acids.
The packaging of these molecules into protocells, droplets with membrane that maintained an internal chemistry diffrent from that of their surroundings.
the origins of self replicating molecules that eventually made inheritance possible
phylogeny and the tree of life
How phylogenies are inferred
Characters that are useful for classifying one group of organisms may not be useful for another organisms.
If DNA or other new evidence indicates that an organism has been misclassified, the organism may be reclassified to accurately reflect its evolutionary history.
Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with very different structures and genetic sequences.
To infer phylogeny, homology must be distinguished from analogy.
Computer programs are used to align comparable DNA sequences and to distinguished molecular homologies from coincidental matches between taxa that diverged long ago.
Constructing phylogenic trees
Main branch represents the common ancestor of all the animal groups shown in the tree.
Each horizontal branch represents an evolutionary lineage. The length of the branch is abritary unless the diagram specifies that the branch length represents information such as time or amount of gene change
Each position along a branch represents an ancestor in the lineage leading to the taxon named of the tip.
Sister taxa are groups of organisms that share a common ancestor that is not shared by any other group. Ex of sister taxa are humans and chimps.
Importance of genome
Linnaeus binomial classification system gives organisms two-part names. A genus plus a specific epithet
Species are grouped in increasingly broad taxa, related genera are placed in the same family, families in orders , orders in classes, classes in phyla, phyla in kingdoms, and kingdoms in domains.
Systematic depict evolutionary relationships branching phylogenetic trees.
Molecular clock
An approach for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates
Different times of change
punctual vs gradual
Events causing changes
An assumption underlying the molecular clock is that the number of nucleotide substitutions in orthologous genes is proportional to the time that has elapsed since the genes branched from their common ancestor