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120 Cards in this Set
- Front
- Back
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patterns in the history of life
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- complex history of multi-cellular life
- 5 major extinctions occured at the end of the following ages (most recent to most ancient) - Cretaceous, -triassic -permian (HUGE: 250 mya, 90% of all marine species went extinct) -devonian -cambrian |
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what causes these extinctions?
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- continental drift
- geological and geographic shifts (plate tectonics) - plate tectonics and continental drift have had a large impact on biotic evolution: - major determinant of species distribution |
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what happened in the Permian era
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- there were huge expanses of tropical, shallow marine communities among continental borders
- defines boundary between Palezoic and Mezosoic periods - impacted land organisms as well |
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Cause of Permian extinction
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- formation of Pangea
-250 mya - all landmasses on earth joined into one super continent, Pangea - shallow marine environments dissapeared - oceans and their currents changed - climate on land changed (became colder and drier as tropical regions decreased) - environmental changes happened on a scale of a few million years (with an average temperature change of 7 degrees C) - this was the largest global extinction yet to occur |
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projected change in global temperatures over the next century
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- 2-5 degrees C
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other reasons for extinctions
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- bolide collisions
- ex: the meteor during the crustaceous period - bring about climate change - typically occurs over a few million years |
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Permian vs. Crustaceous
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- Permian- 95% marine mammals went extinct
- Crustaceous- dinosaurs went extinct |
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Climate change
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- milankovitch cycles
- been operating over time - 1. eccentricity - 2. obliquity - 3. precession of equinoxes |
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eccentricity
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- has to do with distance of earth from the sun
- we're on an elliptical orbit from the sun, sometimes we are very far away and swinging about the middle we are much closer |
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obliquity
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- the tilt that the earth has on our axis
- it can become more or less vertical, if axis is vertical there is little to no seasons in each continent because no one will be closer to the sun |
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precession of equinoxes
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- which ever hemisphere is tilted toward the sun is etting more sunlight
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origin of life
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- living things require energy to survive and can reproduce themselves
- share common properties such as - cells - growth - development - reproduction - regulation - homeostasis - responsiveness - heredity |
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early atmosphere of earth
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- no oxygen
- reducing atmosphere favors large polymers |
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RNA
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- early self replicating molecule
- formed from simple precursors - each molecule was template for new molecules - can catalyze its own polymerization |
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Coacervates
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- demonstrates one way in which cells may have evolved becauase they provide the physical structure by which internal conditions could be differientiated from external conditions
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requirements for early life
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- polymerization
- catalysis - packaging |
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Polymerization
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- easy, perhaps inevitable
- in reducing environment- no oxygen |
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Catalysis
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- RNA may have been both first genetic material and first biological catalyst
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Packaging
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- Oparin's experiment demonstrate that cellular structures could arise from simple precursor molecules and differentiate internal and external environments
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early prokaryotic life
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- presence of particular metabolic processes in all modern organisms implies that processes evolved early on in the common ancestor of living things
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The Tree of life
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- Common ancestor
- Bacteria (own group) - Archaea + Eukarya (protists own group) then (Plantae, fungi, animalia) |
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Cause of Cretaceous mass extinction
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- extra-terrestrial bolide impact
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cause of Permian extinction
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- Pangea
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3 factors constituting mass extinction
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- all external
- continental drift - Bolide Impact - climate changes |
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climate changes
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- Milankovitch cycles
- volcanism |
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Milankovitch cycle
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1. eccentricity
2. obliquity 3. precession of equinoxes |
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eccencricity
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- distance of earth from the sun
- we're on an ellipitcal orbit, sometimes we are very far away from the sun ad swining about the middle we are much closer |
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obliquity
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- deals with the tilt our earth has on our axis
- it can become more or less vertical - if the axis is vertical there will be little to no seasons in each continent because no one will be closer to the sun |
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precession of equinoxes
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- which ever hemisphere is tilted toward the sun is getting more sunlight
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Volcanism
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- short dramatic impacts that have to do with our climates
- ex: little ice age- it snowed in New England in July because a year ago a volancano erupted and ash blocked the atmosphere causing the climate to change for a couple of years |
|
|
patterns in the history of life
|
- complex history of multi-cellular life
- 5 major extinctions occured at the end of the following ages (most recent to most ancient) - Cretaceous, -triassic -permian (HUGE: 250 mya, 90% of all marine species went extinct) -devonian -cambrian |
|
|
what causes these extinctions?
|
- continental drift
- geological and geographic shifts (plate tectonics) - plate tectonics and continental drift have had a large impact on biotic evolution: - major determinant of species distribution |
|
|
what happened in the Permian era
|
- there were huge expanses of tropical, shallow marine communities among continental borders
- defines boundary between Palezoic and Mezosoic periods - impacted land organisms as well |
|
|
Cause of Permian extinction
|
- formation of Pangea
-250 mya - all landmasses on earth joined into one super continent, Pangea - shallow marine environments dissapeared - oceans and their currents changed - climate on land changed (became colder and drier as tropical regions decreased) - environmental changes happened on a scale of a few million years (with an average temperature change of 7 degrees C) - this was the largest global extinction yet to occur |
|
|
projected change in global temperatures over the next century
|
- 2-5 degrees C
|
|
|
other reasons for extinctions
|
- bolide collisions
- ex: the meteor during the crustaceous period - bring about climate change - typically occurs over a few million years |
|
|
Permian vs. Crustaceous
|
- Permian- 95% marine mammals went extinct
- Crustaceous- dinosaurs went extinct |
|
|
Climate change
|
- milankovitch cycles
- been operating over time - 1. eccentricity - 2. obliquity - 3. precession of equinoxes |
|
|
eccentricity
|
- has to do with distance of earth from the sun
- we're on an elliptical orbit from the sun, sometimes we are very far away and swinging about the middle we are much closer |
|
|
obliquity
|
- the tilt that the earth has on our axis
- it can become more or less vertical, if axis is vertical there is little to no seasons in each continent because no one will be closer to the sun |
|
|
precession of equinoxes
|
- which ever hemisphere is tilted toward the sun is etting more sunlight
|
|
|
origin of life
|
- living things require energy to survive and can reproduce themselves
- share common properties such as - cells - growth - development - reproduction - regulation - homeostasis - responsiveness - heredity |
|
|
early atmosphere of earth
|
- no oxygen
- reducing atmosphere favors large polymers |
|
|
RNA
|
- early self replicating molecule
- formed from simple precursors - each molecule was template for new molecules - can catalyze its own polymerization |
|
|
Coacervates
|
- demonstrates one way in which cells may have evolved becauase they provide the physical structure by which internal conditions could be differientiated from external conditions
|
|
|
early earths atmosphere
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- no oxygen
- reducing atmosphere favors formation of large polymers |
|
|
RNA
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- likely the first genetic material
- formed from simple precursors - each molecule was a template for new molecules - can catalyze its own polymerization |
|
|
coacervates
|
- demonstarted one way in which cells may have evolved because they provide the physical structure by which internal and external conditions could be differentiated from external conditions
|
|
|
requirements for early life
|
- polymerization
- catalysis - packaging |
|
|
polymerization
|
- easy, perhaps inevitable in reducing environment (no oxygen)
|
|
|
catalysis
|
- RNA may have been both first genetic material and first biological catalyst
|
|
|
Packaging
|
- Oparin's experiments demonstrated that cellular structures could arise from simple precursor molecules and differentiate inernal and external environments
|
|
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early prokaryotic life
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- presence of particular metabolic processes like glycolysis and ATP as energy source in all modern organisms implies that the processes evolved early on in the common ancestor of all living things
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bioitic evolution
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- plate tectonics
- continental drift |
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Cause of Permian extinction
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- Pangaea
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Cause of cretaceaous
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- extra terrestrial bolide impact
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3 factors of mass extinction
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- all external
- Continental drift - bolide impact - Climate change |
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|
Climate change
|
- Milankovitch cycles
- volcanism |
|
|
Milankovitch cycles
|
1. eccentricity
2. obliquity 3. precession of equinoxes |
|
|
eccentricity
|
- has to do with how far away the sun is from earth
- since we are on an ellipitical orbit - distance from sun |
|
|
obliquity
|
-the tilt that the earth has on our axis
- can become more or less vertical - if is completely vertical there will be little to no seasons in each continent because no one will be closer to the sun |
|
|
precession of equinoxes
|
- what hemisphere is tilted toward the sun
- which ever is tilted to the sun is getting more sunight |
|
|
volcanism
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- short dramatic impacts that have to do with our climates
- ex: little ice age- it snowed in New England in July because a year ago volcano erupted and ash blocked the atmosphere causing the climate to change dramatically for a couple of years |
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adaptive radiation
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- often follows mass extinction
- ecological opportunity- vacant niches - release from pathogens such as predators and other limiting factors |
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triggers of adaptive radiation
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- extinction
- colonization - morpholigical innovation ** critical component is ecological opportunity |
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phylogeny
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- evolutionary history of life
- dictated by DNA, morphology and molecular data |
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Phylogeny dictated by
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- DNA
- morphology - molecular data |
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Systematics
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- science trying to organize phylogeny
- the study of evolutionary relationships - you are looking to get the correct phylogeny |
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major goal of evolutionary biology
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- reconstruct life history on earth
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how to trace phylogeny
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- use evidence from paleontology
- molecular data - comparative anatomy and other approaches |
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main goal of systematics
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- tracing phylogeny
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phylogenetic trees
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- graphic representations of relationships
- reflect the hierarchical evolutionary relationships of organisms - constructed from a series of dichotomies that depict a relationship - also called a cladogram |
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sequence of branching
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- symbolizes historical chronology
- nodes on the tree represent hypothesized common ancestors |
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cladistics
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- each branch or clade can be nested with larger clades
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clade
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- consists of ancestral species and all of its descendants
- also called monophyletic group - those not fitting this definition are not natural groups and are not accepted in clidistics |
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polyphyletic group
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- similar organisms without common ancestor
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paraphyletic group
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- including common ancestor but not all descendents
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monophyletic
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- common ancestor and all descendants
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cladistic analysis relies on
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- relies on the pattern of shared, derived character states among taxa to infer relationship
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Homologs
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- similiarities based on shared ancestry
- shared feature due to common ancestry - ex: embryological homology |
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phylogenetic realtionships are inferred from
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- pattern of shared homologous characters
- taxa that share derived character states should be more closely related to each other than to taxa lacking those derived states - more homologous parts or derived character states that the two species share the more closely related they are |
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complex structures
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- the more complex structures are the less likely that they evolved independently
- highly impropable that skulls of human and chimp, matching in so many details have seperate origin |
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homoplasy
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- similarites based on convergent evolution
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apomorphy
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- derived trait, derived from common ancestor
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plesiomorphy
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- primitive trait
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synapomorphy
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- shared derived trait
- homolog - shared trait from common ancestor |
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symplesiomorphy
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- shared primitive trait
- analogs - similiar trait but different common ancestor, evolving independently |
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phylogenetic relationships inferred from shared homologous characters
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- 0- trait absent in taxa, no info about relationship
- 1- trait present in taxa, shows relationships, used to find how realted taxa are to each other -taxa have common ancestor if trait is shared |
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Ingroup
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- ingroup is a group of interest
- you compare it to an outgroup, that outside of interest - if taxa share alot of traits they have recently diverged from one another - phylogenetic trees provide the best evidence of how evolution progressed |
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primitive traits
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- plesiomorphy
- are derived traits at a more inclusive level of tree - synapomorphies for group are symplesiomorphies at higher less inclusive levels of the tree |
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outgroup
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- outgroup comparison is used to differentiate shared primitive characters from shared derived characters
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identifying outgroup
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- a species or group of species that is closely related to the species that we are studying- ingroup
- but they must be known to be less closely related than any ingroup members are to each other |
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conclusion from outgroup study
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- character states exhibited by outgroup and shared with ingroup are assumed ancestral and primitive
- other states are considered derived, only characteristic of ingroup |
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principle of parsimony
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- the simplest explanation is the best explanation
- best phylogenetic tree is the one with the fewest steps |
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comparative biology
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- phylogenetic trees are basis for all comparative biological analyses
- saying that genes in mice are the same as genes in humans suggest that they share a common ancestor - in order to make these claims you must know the phylogeny |
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molecular data
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- revolutionized the understanding of evolutionary relationships
- assists in dating evolutionary events like when HIV came to humans |
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whale example using molecular data
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- based on the whale fossil record Gingerich said whales were carnivores and most closely relatied to sea lions
- molecular analysis showed that wahles are artiodactyls and most closely related to hippos - Gingerich was confused by the homoplasy but the following year he found fossils of whales with limbs, ankle bone was clearly that of artiodactyl |
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molecular data and dating evolutionary events
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- many molecules evolve in a roughly clock like manner
- can date when HIV first came to humans |
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hierarchy
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- use cladograms to place species in taxonomic hierarchy
- some systematiss argue that Linnean hierarchial system is wrong because classification must be rearrange when find new evidence - however phylogenetic classification easily accomodates change |
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origin of HIV
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- HIV is related to SIV in chimps
- HIV derived multiple times from SIV - HIV 1 causes most damage in humans is derived 3 times from SIV - HIV 2 is derived 3 times from sooty mangabeys |
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possible origins of contractions of HIV
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- possibility contracted from chimps and mangabeys by eating them
- we are closely related to them so we are infected by the same viruses |
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HIV court case
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- 1994
- first use of phylogenetic analyses in court - gastroenterologist infected ex gf with HIV from patient - used phylogenetic analysis to show gf injected with same strain as patient - strains are part of the same clade |
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common themes in evolution of genomes and development
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1. realtively few genes in genome
2. conservation of genetic tool kit 3. genome duplication 4. gene or segmental duplication 5. gene silencing 6. genetic redeployment during development 7. evolutionary change in timing and place of gene expression 8. rapid evolution of gene regulatory regions |
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relatively few genes in genome
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- most mammals have 20,000 genes which is 1/5 what we thought that they would have
- humans 20- 25k - plants 26 k- arbidopsis |
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conservation of genetic toolkit
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- many genes are invovled in defining body plans are conserved across different species
- HOX genes- set of genes that control early stages of embryonic development |
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HOX genes
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- set of genes that control early stages of embryonic development
- establish the axis of the body and determine what body segments will be - determines prescence or absence of appendages in fruit flies *** genes are arranged in the same order on chromosomes as they are expressed in the body plan |
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genome duplication
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- common in plants
- rare in animals but has occured - ex: evolution of HOX genes clusters- 2 rounds of duplication between amphioxus and vertebrates and another round in the lineage of the bony fish - duplication leads to duplicate copies of genes - duplicate copies of genes leads to mutation and new functions - mutations can be beneficial but they usually result in gene silencing (non functional copies/ pseudogenes) |
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gene or segmental duplication
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- more common than entire genome duplication
- same idea as before, new genes allow for more variation and mutations which can lead to new functions - usually bad, gene silencing |
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gene silencing
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- ex: 70% of human OR genes are inactive
- chimps have more OR genes than us because they need their sense of smell more to survive than we do |
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redeployment of existing genes for a new function
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- distal-less gene
- gene expressed in developing leg is now expressed in the butterfly wing as an eyespot that startles predators |
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evolutionary change in timing and place of gene expression
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- heterochrony
- heterotropy |
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heterochrony
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- evolutionary change in the timing of developmental events
- ex: humans are slowed down chimps- our development has been slowed down so we have developed larger brains |
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heterotropy
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- evolutionary change in place of developmental events
- ex: distal-less gene - ex: pectoral girdle in human |
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pectoral girdle
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- heterotropy
- in human girdle slides over the rib cage - in turtle it is found inside the ribs - during development turtle rib cells migrate laterally out to the sides so their scapula develops inside their ribs |
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rapid evolution of gene regulatory regions
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- regulatory regions are regions of DNA that are bound by proteins that control expression of the gene- turn it on and off
- Rockman and Wray 2002- found that 67 of the 107 genes examined had regulatory sequence variations that had significant effects on gene expression |
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2 hypotheses explaining the paradox of development
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1. many genetic differences among species- WRONG
2. differences in how similiar genes are deployed during development- best hypothesis |
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genes during development
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- genes are deployed and regulated differently during development
- this changes how they are expressed and whether or not they are inactive or acive - best hypothesis in explaining the paradox of development |
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genetic regulation of expression and development
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1. hierarchical control of gene expression
2. modularity of gene expression |
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hierarchical control of gene expression
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- some genes- early- need to be expressed before other genes-late- can be expressed
- ex: in fruit flies, early gene products activate or inhibit genes that act later - this ensures that genes are expressed at the proper time during development |
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modularity of gene expression
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- genes are expressed in specific places and at specific times
- differential expression of activators and ihbitors in different body body regions allows for spatial differentiation of the body - different expression of activations and inhibitiors in differnt body regions allows for spatial differentiation in the body - ex: combinatorial control of eve expression- the place of expression of the eve stripe 2 gene is determined by concentration gradients of other gene products - eve can't be positioned in the same place as gene products that inhbit it (giant and hunchback) but is located in the same place as gene products that activate it (bcd and kr) |
