History of life on earth Flashcards
Earth and its moon formed
4.6bya ago
Stages through which simple cells were formed
I)abiotic synthesis of small organic molecules
II)joining organic molecules to form macromolecules
III)packaging of macromolecules into protocells
IV)origin of self replicating molecules that eventually made inheritance possible
Micro evolution
How populations change over time
Macro evolution
Large scale changes in large taxonomic groups over long periods of time
Relative dating
Comparing sedimentary strata to find the relative ages of fossil with the assumption those deeper in the sedimentary rock are older than those more shallow In sedimentary rock
Radiometric dating
Finding the absolute ages of fossils by measuring radioactive isotopes and decay products
Half life
Time required for parent isotope to decay
Radiocarbon dating
Most common radio metric dating, measures the carbon isotope 14c and its decay products
Geologic time scale
Is a system of chronological dating used to describe the timing and relationship of events in geologic history
Geologic time scale
Eons, eras,periods, epochs, ages
(Oldest to newest)
Major events in life history
I)first life on earth
II)oxygen revolution
III)origin of first eukaryotes
IV) origin of first multicellular organisms
Stromatolites
Oldest known fossils, they are rocked formed by the accumulation of sedimentary rocks on microbial mats
Microbial mats
Multilayered sheets of prokaryotes
Stromatolites
Date back to 3.5 bya
First life On earth
Prokaryotes most likely bacteria
Oxygen revolution
2.4 to 2 bya
Oldest known eukaryotic fossils
Protists, date back to 2.1 bya
Endosymbiosis
Process where prokaryotic cell is engulfed by the host cell (and over time the engulfed cell becomes a dependent part of the host cell)
Primary endosymbiosis
Engulfed prokaryote developes into a cell structure within a eukaryotic cell
Secondary endosymbiosis
Product of endosymbiosis is engulfed and retained by another free living eukaryote
Evidence for endosymbiosis
I)inner structure of mitochondria and chloroplasts looks like the plasma membrane of prokaryotes
Evidence for endosymbiosis
II)mitochondria and chloroplasts can transcribe and translate their own DNA regardless of the cell they’re In
Evidence for endosymbiosis
III) division and DNA structure in mitochondria and chloroplasts are similar if some prokaryotes
Evidence for endosymbiosis
IV)Their ribosomes are more similar to prokaryotes than eukaryotes
Origin of first multicellular organisms
Algae, which dates back to 1.2 bya
Ediacaran biota
Assemblage of larger and more diverse soft bodied organisms that lived in the ediacaran period from 635 to 541 mya
Cambrian explosion
Period where animal fossils most resembling most modern animal phyla started suddenly appearing about 541 mya ( number of animals diversified rapidly)
Hypothesis for Cambrian explosion
I)predator-prey relationships
Hypothesis for Cambrian explosion
II)rise in atmospheric oxygen level led to increased metabolic rate and body size.
Hypothesis for Cambrian explosion
III) evolution of hox gene complexes (regulate development of animal body) resulted in developmental flexibility
Hox gene complexes
Regulate development of animal body
Fungi and plants colonization
500 mya
Plate tectonics
Earth’s crust is composed of plates rotating on earth’s mantle which are capable of slow, large scale movements.
Mass extinction
When rate of extinction does not occur at a normal constant rate, but occurs dramatically
Mass extinction is the result of
Disruptive global environmental changes
End permian
Largest mass extinction,81% marine species lost and 70% terrestrial vertebrates
End cretaceous
Most well known mass extinction, 65 mya wiped out non avian reptiles
Consequences of mass extinctions
I) can alter ecological communities and the niches available to them
Consequences of mass extinction
II) can take 5-100 million years for diversity to recover
Consequences of mass extinctions
III) can change the type of organisms found in ecological communities
Adaptive radiation
Rapid evolution of diversely adapted species from a single common ancestor within a relatively short time span.
Adaptive radiation may follow
I) mass extinctions
II)the evolution of novel characteristics
III)colonization of new geographic areas
What evolutionary process occurs after a mass extinction
Adaptive radiation
