Evolution (Chapter 25 The History of Life on Earth_Macroevolution…
Chapter 25 The History of Life on Earth_Macroevolution
Hypothesis of simple cells produced :4 main stages
Macromolecules packing together into
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
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
Documents of history of life -- 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
the decay of radioactive isotopes expressed by the half-life (50% decay)
measuring the ratios of isotope C14 and C12 in a fossil to datermine fossils age. Half life of isotope carbon is 5730 years
limitation for fossils
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
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
: 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
Gymnosperm, dinosaurs evolve, and origin of mammals
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
Homo sapiens evolve: 2.6 million to 001 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
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
: alterations in genes that effect the location of body parts. Hox genes change can impact morphology of organisms
: 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.
change in regulation of gene expression limited to one cell type, fewer harmful, may be caused by mutation.
Plate tectonics and mass extinction
: 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
new species would adapt different ecological roles, or niches, in their communities.
Sixth mass extinction maybe happened because of human actions
Phylogeny and the Tree of Life:
An understanding of Evolutionary Relationships
Important vocabulary concepts:
Phylogeny is how biologist trace the evolutionary history of a specie or a group of species.
a system that classifies organisms and determines their evolutionary relationships.
A discipline that studies how organisms are named and classified.
The named taxonomy unit at any level of the hierarchy.
Understanding a phylogeny is a lot like reading a family tree. The root of the tree represents the ancestral lineage, and the tips of the branches represent the descendants of that ancestor. As you move from the root to the tips, you are moving forward in time.
How does taxonomy works?
-avoiding ambiguity : naming of species
two-part format of scientific name is a binomial: First part
( plurals genera) to which the species belong Second part: is called s
a unique name for each species within the genus.
- Species were classified into a hierarchy of exclusive categories.
1 . Genus
: closely related species
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Taxonomy disadvantages originated in the Linnaean classification:
Some species have been placed within a genus or group, where the species is not closely related.
It tells nothing about the evolutionary relationship to one another.
Classification based entirely of evolutionary relationships
Names are only assigned to groups that include common ancestors and all of its descendants.
How is this done?
Hypothesis about evolutionary relationships
1. Ancestral Lineage
: Branch point represents the common ancestor of taxa A-G
2. Branch point where lineage diverge
3. Common ancestor of taxa A B
4. B and C diverged after their shared lineage split from the lineage leading to taxon A
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5. This branch point forms polytomy: an unresolved pattern divergence
Polytomy: A branch point from which more than two descendant groups emerge.
Taxon G : Basal Taxon
Basal Taxon: lineage that diverges early in the history of a group
They show pattern of descent not phenotypic similarity
The Sequence of branching does not indicate the absolute ages of the particular species.
a taxon on a phylogenetic tree evolved from the taxon next to it.