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Evolution (Chapter 25 The History of Life on Earth_Macroevolution…
Evolution
Chapter 25 The History of Life on Earth_Macroevolution
Hypothesis of simple cells produced :4 main stages
Macromolecules packing together into
protocell
which refers to droplets with membranes that maintained internal chemistry different from that of their surroundings.
Vesicles could be produced by lipid or other organic compounds and water. vesicles have bilayer which seems to plasma membrane and can reproduce themselves.
The nonliving synthesis of small organic compounds: amino acid
Stanley Miller and Hard Urey test
2 hypothesis
Organic compound was formed at environment like volcanic eruption
Organic compound was formed in deep-sea hydrothermal vents and alkaline events
Hydrothermal vents has hot water (300-400'C)so that the organic compounds may not be stable
alkaline vents is warm water (40-90'C) more suitable for organic compounds
Self-replication RNA_enzyme-like catalyst: Ribozymes
2014 Dr. Jack Szostak and college students test: copying template strand of RNA occurred in a built vesicle. If this vesicle can pass its RNA to its 'daughters' . the daughters would be
protocells
.
Small moleculars join into macromolecules.
2009 study the abiotic synthesis of RNA monomers can occur spontaneously from simple precursor molecules
the poly mers formed spontaneously without the help of enzymes or ribosomes
Documents of history of life -- fossils
Fossils
fossils accumulated in sedimentary rock layers (strata)
Insects preserved in amber(fossilized tree sap) and mammals frozen in ice
Ancient microbes left their mark through atmospheric oxygen in the form of rusting iron-rich terrestrial rock
Identify fossils
Radiometric dating:
the decay of radioactive isotopes expressed by the half-life (50% decay)
Carbon dating:
measuring the ratios of isotope C14 and C12 in a fossil to datermine fossils age. Half life of isotope carbon is 5730 years
Limitation
limitation for fossils
Incomplete
Organisms did not die in the right place and right time to form fossil
Fossils were destroyed by later geologic processes
Biased in favor of some species
Limitation for carbon dating
Only works for fossils up to about 75,000 years old
Geologic record
a standard time scale that divides Earth's history into 4 eons and further subdivisions
Archaean: 4.0 billion to 2.5 billion years ago
Oldest known rock on Earth's surface
Oldest fossils of cells (prokaryotes) appear
First life 3.5 billion years ago
Concentration of atmospheric oxygen begins to increase
First oxygen producer: 2.7 billion years ago,like cyanobacteria
Proterozoic: 2.5 billion to 0.5 billion years ago
Oldest fossil of eukaryotic cells appear
First Eukaryotic: 1.8 billion years ago. originated by
endosymbiosis
: when a prokaryotic cell engulfed a small cell that would evolve into an organelle found in all eukaryotes, the mitochondrion
Era: Neoproterozoic: 1.0 billion to 0.5 billion years ago
#
Diverse algae and soft-bodied invertebrate animals appear
First multicellular organism: 1.8 billion or 1.2 billion years ago for small, 0.6 billion years ago for bigger ones
Haden: 4.6 billion years ago
Origin of earth
Phanerozoic : 0.5 billion to 0.01 million years ago
Era: 3 different eras
Mesozoic: 0.25 billion to 66 million years ago
Flower plants (angiosperm), dinosaurs extinct 145--66 million years ago
Gymnosperm, dinosaurs evolve, and origin of mammals 225million years to 145 million years ago
Cenozoic: 66 million to 0.01 million years ago
Angiosperm and mammalian orders
origins of primate groups, earliest direct human ancestors, and appearance of bipedal human ancestors
Radiation of mammals, birds , and pollinating insects
Ice ages
Homo sapiens evolve: 2.6 million to 0.01 million years ago
Paleozoic: 0.54 billion to 0.25 billion years ago
Marin algae abundant; colonization of land by diverse fungi, plants and animals
First landed: 0.5 billion years ago.
Early vacular plants
Cambrian explosion: many animal phyla
Explosive of most animal phyla: 0.535--0.525 billion years ago sponges, cnidarians, and molluscs
Bony fish, first tetrapods and insects
Forests of vascular plants form, first seed plants and origin of reptiles, amphibians dominant
Extinctions of many marine and terrestrial organisms
Plate tectonics and mass extinction
Plate tectonics
: the continents are part of great plates of Earth's crust that essentially float on the hot, underlying portion of the mantle.
Consequence of continental drift
The Earth's plates formed 8 super continents.
4 ways affected terrestrial evolution
Pangaea destroyed shallow water habitats
Climate changes: Canada used to be in the tropics
Promotes allopatric speciation
Help geogrophic distribution of extinct organisms
Mass extinction and consequences
Permian: 251 million years ago, claimed 96% of life, caused by extreme volcanism in past 500 years
Trianssic: 200 million years ago, caused by climate change, asteroid impact, flood eruption
Late devonian: 360 million years ago, life in shallow seas most affected, 3/4 died out, caused by asteroid massive flood of lava/ oxygen decreased
Crestaceous: 65.5 million years ago.extinguished more than 1/2 of marine species, death of dinosaurs, caused by iridium (elements common in meteorites)
Ordavian: 488.3 million to 443.7 million years ago, affected most life in the sea, caused by carbon dioxide decreased
Consequences of mass extinction
Adaptive radiations:
new species would adapt different ecological roles, or niches, in their communities.
Sixth mass extinction maybe happened because of human actions
Evolution is not goal oriented
Evolution novelties: complex structure of eyes. evolved from a series of steps, throughout time, eyes retained their basic function of vision.
Evolution trends: 'differential speciation success' plays a role in macroevolution similiar to the role of differential reproductive success in microevolution. evolutionary trends result directly from natural selection
Genes' sequences and regulation impact body form
Rate and timing:
sexually mature stage of a species may retain body features that were juvenile structures in an ancestral species, called
paedomorphosis
Spatial pattern
: alterations in genes that effect the location of body parts. Hox genes change can impact morphology of organisms
Genes sequence
: particular changes in the nucleotide sequence of a developmental gene contributed to a major evolutionary change: the origin of the six-leg insect body plan.
Gene regulation:
change in regulation of gene expression limited to one cell type, fewer harmful, may be caused by mutation.
Chapter 26 Phylogeny and The tree of Life
systemetics:
a discipline focused on classifying organisms and determining their evolutionary relationship.
Phylogeny:
the evolutionary history of a species or a group of species
Taxonomy:
scientific discipline to name and classify organisms.
Hierarchical classification
species--genera--family--orders-classes--phyla--kingdoms--domains
taxon:
the taxonomic unit at any level of the hierarchy. Taxon broader than the genus are not italicized, though they are capitalized.
Binomial nomenclature:
contains two parts and the fist letter of genus should be capitalized. printing needs to be italicized, writing needs to be underlined. eg.
Homo sapiens
second part: specific epithet (species)
First part: genus
Phylogeny
: likes family tree used to represent the evolutionary history of group of organisms.
Read phylogenic tree
Branch Point:
represent the common ancestor of the two evolutionary lineages diverging from it.
Sister Taxa
: groups of orgaisms that share an immediate common ancestor that is not shared by any other group. e.g. human and chimps
Basal Taxon
: the organisms near to the common ancestor than others in the group. Figure 26.5
Inferred from morphological and molecular data: Similar morphologies or similar DNA sequences are likely to be more closely .
Molecuar data
Anologies: share same environment_convergence
Homologies: share same ancestor_divergence
Bioinformatic: technology that systemetic organize biological data. The computer programs used to align comparable DNA segments of different length.
Molecular systemetic: use of molecular genetics to study the relationships among individual and species.
shared characters for hypothesis of phylogeny
Clades:
an ancestral species and all of its descendants.
monophyletic group: consits of ancestral species and all of its descendants
Paraphyletic group: consists of an ancestral species and some of its descendants but not all of them
Polyphyletic group: the most recent common ancestor of its members is not part of the group.
shared ancestral: originated in an ancestor of the taxon
shared derived character: an evolutionary novelty unique to a clade. also can refer to the loss of a feature.
infer evolutionary relationships with each shared derive character first appeared.
Principle of maximum parsimony: simplist explanation is consistent with facts.
Genome documents the evolution history of organisms
Help to relate organisms who look nothing alike. e.g. animals and fungi
orthologous: homologous gene maintain similar functions_all of descendants have the characters
paralogous: homologous gene_new function (mutation)_not share with all of descendants.
genome evolution:
lineages that diverged long ago often share many orthologous genes
the number of genes a species has doesn't seem to increase through duplication at the same rate as perceived phenotypic complexity.
molecular clock and its application
molecular clock
: the average rate at which a species' genome accumulates mutations, used to measure their evolutionary divergence and in other calculation.
Determine molecular clock: the portion of DNA changes compared with different DNA's change rate to find average rates of the DNA to estimate the dates of events without fossil record.
molecular clock limits: natural selection may favored certain DNA over others. only works about 550 million years.
applying: date the origin of HIV infection in human.
The tree of life is changing
Horizontal gene transfer: genes are transferred from one genome to another through mechanisms.
viral infection
fusions of organisms
exchange of transposable elements and plasmids
example for horizontal gene transfer
in prokaryotes:
transduction: transfer of genetic material by a plasmid or bacteriophage
conjugation: direct transfer of DNA between two cells
transformation: cells pick up free DNA from enviroment
in eukaryotes
DNA must pass through both the outer cell membrane and the nuclear membrane to reach eukaryotes genome.
Horizontal gene transfer may have been very common in the early history of life that the base of a "tree of life". might be more accurately portrayed as a tangled web.