Chapter 3 Geological History Flashcards
3.9-2.5 BYA
Evidence lost due to remelting of old rock and formation of new.
Marked by presence of oldest known rocks
Meteors hitting earth
Earliest evidence of life is bacteria and blue-green algae from 3.5 BYA
Stromatolites
M
Archean Eon
4.6-3.9 billion years ago
Earth was hot consisting of molten rock and water in gaseous state.
No evidence of life
Hadean Eon
2.5-0.6 BYA 1-2 continents Seas becoming salty from land runoff Oxygen accumulates in sea and atmosphere Atmospheric shield begins to protect from UV rays Continuation of prokaryotes 1st eukaryotes 2.1 BYA New life forms arose in shallow seas Segmented worms, Arthropods, algae.
Proterozoic Eon
590 MYA to present day
Divided into 3 eras.
Super continent Pangea, continents break up.
Periods of hot and cold (glaciation)
Shallow seas drying up and inundating land.
Explosion of diversity in life forms
Several extinction events followed by new species.
Phanerozoic Eon
590-248 MYA
Most continents joined, some northern continents separate.
All-time low regression of sea.
Cambrian explosion of new life forms.
1st vertebrate, fish, amphibian, reptile.
1st insects after time.
Ends with the greatest extinction event ever!!!
Paleozoic Era
Up to 96% of all marine species went extinct. 70% of terrestrial vertebrates went extinct.
Mass extinction of insects.
Cause of extinction event is unknown. (volcano, bolide impact, sea level change, methane release)
Permian Triassic extinction event
248-65 MYA
Age of reptiles. Subdivided periods: Triassic, Jurassic, Cretaceous.
Begins with one Pangea and one Pathallasa
Early Jurassic, northern continents separate off as Laurasia.
Southern continents stay together as Gondwanaland.
Warm climate mostly.
1st mammals early, 1st dinosaurs rule most of the time,
1st birds and first flowering plants. Much diversity
Ends with the 2nd greatest extinction event ever. K-T boundary
All large dinosaurs and vertebrates went extinct.
Mammals, fish, land plants mostly survived
Cause = bolide impact
Mesozoic Era
65 MYA to present day “age of mammals”
Continents move to current locations
Adaptive radiation and evolution of current biota
Cenozoic Era
(2MYA - 10,000 YA) Significant cooling and glaciations
Pleistocene Epoch
70 MYA made for the first time connecting Alaska and Siberia.
3-6 MYA marine corridor runs through.
Ice ages change sea level and bridge re-submerges multiple times
Beringia
Direct effects of glaciation:
Totally covered and scoured some parts of northern hemisphere.
Dumped glacial debris
Force biota to move south some later return after warming
Scoured out valleys
Rerouted rivers
Dammed or created lakes
Sea levels fell by as much as 100m
Land bridges formed such as Beringia
Affected climate worldwide, generally drier and cooler in tropics.
Causes to Pleistocene glaciations due to changes in earths orbit, thus changes in the amount of solar radiation received.
Milankovich Cycles
Variation in ellipticity of the Earth’s orbit.
Eccentricity
Biota responses for survival:
Move
Adapt
Die
A single evolutionary line. (George Simpson)
Evolutionary Species Concept
A group of species with the same type of morphological characteristics.
“Type Specimen” - identified and described and recognized by similarity to the type specimen.
Typological Species Concept
Groups of interbreeding natural populations that are reproductively isolated from other such groups (Mayr)
Group of organisms that can interbreed naturally and produce fertile offspring.
Biological Species Concept
Like biological concept but also…. a group of organisms that can interbreed and produce fertile offspring AND produce offspring at least as fertile and adaptive as the parent strains.
-not applicable for asexual reproduction.
Ecological Species Concept
The functional unit of heredity, a discrete piece of DNA that contains info affecting one or more trace.
Gene
Different forms of a gene.
Allele
One individuals set of genes.
Genotype
Expressed traits determined by genotype.
Phenotype
All of the genes and alleles in a population.
Gene Pool
Transfer of genetic material between populations.
Gene Flow
Increased fitness in highly heterozygous individuals.
Hybrid Vigor
An altered form of a gene; change in its DNA.
Mutation
Change in the genetic composition of a population over time. Usually through series of mutations.
Evolution
A process of genetic change of a population due to natural selection, whereby the population becomes better suited for some feature in its environment.
Adaptation
Evolutionary divergence of a lineage into a variety of adaptive forms.
Adaptive Radiation
Populations diverge and speciation occurs by what two factors?
Genetic Drift and Natural Selection
Change in gene frequency of a population caused solely by chance. (Important in small populations)
Genetic Drift
Differential survival and/or reproduction of organisms due to their hereditary characteristics.
Natural Selection
Occurs after speciation; rapid evolution then little change for a long time.
Punctuated Equilibrium
Small changes in the genetic make-up of a population due to natural selection, mutation, genetic drift, or gene flow.
Micro-evolution
Large changes in the genetic make-up of a population, including speciation.
Macro-evolution
Process by which two or more species arise from one species.
Speciation
Occurs when populations are separated or become isolated by a barrier. Genetic differences due to lack of gene flow between populations. Thus by genetic drift or natural selection.
Allopatric Speciation - “Vicariance”
Speciation within a spatially contiguous population.
One population extends over a wide environmental geographic range.
Ex. Anthoxanthum Grass - contaminated with mine tailings. Some have adapted to grow in mine tailing areas but flowering occurs at separate times therefore reproduction between the two is limited.
Parapatric Speciation
Population in a particular location.
Two modes due to either chromosomal changes or selection for two genotypes in same area.
70-80% of angiosperms formed from chromosomal changes of a few species.
Sympatric Speciation
Elimination of a species alive anywhere.
Dodo bird, Carolina Parakeet
Extinction
The only remaining members of a species are in captivity.
Extinct in the wild
Any species that is totally extinct or extinct in the wild.
Globally extinct
Locally extinct or when a certain species does not occur in a particular locality where it formerly did, but still does occur in other areas.
Extirpated
A population or species whose numbers are so reduced that it has a negligible impact within its community.
Ecologically extinct
A species occurs in only one area and nowhere else.
Endemic Species
A species is in low numbers, or in a small geographic range, or in only a few habitats.
Rare
250 MYA
Largest extinction event ever. Unknown cause
Permian Triassic
65 MYA
2nd most major extinction event.
Dinosaurs went extinct, mammals later become dominant
Accepted cause was a large meteor that hit earth off the coast of Yucatan. Impact killed much life while ejects from impact darkened skies and created a nuclear winter that killed off most life.
Cretaceous Tertiary (K-T)
Due to a dispersal event.
A small founder population leaves the larger population and colonizes a new area. Genetic difference caused by a lack of gene flow, thus by genetic drift or natural selection.
Allopatric Speciation - Peripheral Isolates
