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Chapter 25 & 26 (Chapter 26 Phylogeny & the Tree of Life…
Chapter 25 & 26
Chapter 26 Phylogeny & the Tree of Life
Biological Classification
Grouping living org's by places related genus --> family --> orders --> classes --> phyla --> kingdoms --> domains
Scientific Name
Genus + Specific Epithet
Unique for each species
First letter of genus is capitalized, entire name is italicized & has latin ending
Phylogeny
"The evolutionary history of a group of species - constructed using systematics"
Homologous vs. Analogous
Homologous
Indicates whether or not there is a common ancestor
Analogous
Look/act similar but aren't from common ancestor, but rather convergent evolution (Ex: flying squirrels, bats)
Molecular Homoplasies
Coincidental matches in otherwise very different DNA
Bioinformatics
Biological studies that use computer programming
Molecular Systematics
Use of molecular structures to determine evolutionary relatedness
Clade
"Groupings of organisms that infer phylogeny from homologous patterns"
Monophyletic
Consists of an ancestral species and ALL of its descendants
Paraphyletic
Consists of an ancestral species and SOME of its descendants
Polyphyletic
Consists of distantly related species but doesn't include their most recent common ancestor
Maximum Parsimony
The simplest answer is the most correct
Genes
Genetic Sequences
Used to deduce relatedness by comparing nucleic acids
Molecular Trees
Represents short/long periods of time
Gene Duplication
Results in gene families; like homologous genes, duplicated genes can be traced to a common ancestor
Orthologous Genes
Found in single copy in the genome & are homogenous btw species
Paralogous Genes
Result from gene duplication and are found in more than one copy in the genome
Molecular Clock
"Measures the absolute time of evolutionary change based on observation that some genes & other regions of genomes appear to evolve at constant rates"
Graph the number of genetic differences vs. the dates of evolution (pts known from fossil record)
No concrete dates, estimation
Horizontal Gene Transfer
Process in which genes are transferred from one genome to another
Thru mechanisms such as: exchange of transposable elements/plasmids, infections, fusion chromosomes.
HGF in Prokaryotes
Transformation (uptake of free DNA), conjugation (plasnoid-mediated transfer), transduction (mediated transfer)
HGF in Eukaryotes
Endosymbiosis
(org lives inside), bacteria present in nucleus, nuclear genes from bacteria and archaea
Chapter 25 The History of Life on Earth
Major Events
Fossil Record
Formed in sedimentary rocks
Shows great changes in organisms over time
Incomplete Evolution - many org's didn't die in right place/time to be preserved as fossils
Radiometric Dating
- decay of radioactive isotopes
The "parent" isotope decays to "daughter" at a rate of a half life.
Geologic Record
Proterozoic (3rd eon)
Algae & jellies appear
Oldest fossils of eukaryotes
Archaean (2nd eon)
Atmospheric oxygen increases
Oldest fossils of prokaryotes
Phanerozoic (4th eon)
Cenoxoic Era
(66 mya)
Major radiation of mammals, birds, and insects
Primates, earliest (direct) human ancestor, ice ages
Mesozoic Era
(252 mya)
Dino's evolve, origin of mammals
Flowering plants diversify
Paleozoic Era
(541 mya)
Diversity in animal phyla & plants
Bony fish, tetrapods, insects
Neoproterozoic Era
(2500 mya)
Oldest fossils of eukaryotic cells appear, diverse algae and soft bodied animals (jellies)
Hadean (1st eon)
origin of life (4,600 MYA)
Extra Dates/Info
1st Life on Earth
Approx 3.5 bya
1st Oxygen producers
Approx 2.7 bya
1st Eukaryotes
Approx 2.1 bya
1st multicellular org's
Approx 1.5 bya
Cambrian Explosion
530 mya
First land-dwellers
500 mya
First human
195,000 mya
Continental Drift , Extinctions, Adaptive Radiations
Plate Techtonics
The continents are part of bigger plates of Earths crust that's on the hot, underlying portion of the mantle
Formed a supercontinent 3 times
Continental Drift
Affects:
Alters the habitats org's live
Climate change
Allopatric speciation
Explains the geographic distribution of extinct org's
Mass Extinctions
Ordovician Silurian (439 mya)
Glaciers, falling sea levels, too much oxygen, temperature drops
Late Orvonion (364 mya)
Widespread lack of oxygen in ocean
Permian-Triassic (251 mya)
large amounts of CO2 being released into air. Led to global warming
Triassic-Jurassic (200 mya)
Asteroid impact, climate change
Cretaceous-Paleogene (65 mya)
Asteroid impact, volcanic eruptions, climate
Effects on Changes in Genes
Heterchrony
Evolutionary change in the create of timing of development events
Human & chimp skull develops @ diff rate
Paedomorphosis
Evolutionary process in which larval or juvenile features of an ancestral org are displaces to the adult forms of its descendants
Changes in the Spatial Pattern
Homeotic genes determine such basic features as where wings and legs will develop on a bird, etc.
Changes in Gene Sequence
New morphological forms likely come from gene duplication events that produce new developmental genes
Changes in Gene Regulation
Changes in developmental genes can result in new morphological forms
The Origin of Life
4 Stages of life by Chem evolution
Abiotic Synthesis of organic molecules
Joining small molecules into macro's
(polymerization, and dehydration synthesis)
Packaging of molecules into protocells.
Origin of self-replicating molecules.
(eventually made inheritance possible)
Important People
A.I. Oparin & J.B.S. Haldane
"Earth was a reducing (electron-adding) environment. Organic compounds could've formed from simpler molecules."
Energy could've came from lighting and UV radiation
"
Primitive soup
" - early oceans (a giant soup) were a solution of organic molecules where life arose
Stanley Miller & Harold Urey
Tested their hypothesis by creating lab conditions comparable to those that scientists thought existed on early Earth
Conditions could've allowed the synthesis of organic molecules from inorganic ingredients
Evidence for RNA (1st genetic material?)
RNA monomers have been produced spontaneously from simple molecules.
RNA can self replicate.
They can catalyze many different reactions.
Natural Selection in RNA World
How did N.S. favor proliferation of stable protocells w/ self-replicating, catalic DNA?
RNA molecules that were more stable or replicated more quickly would have left the most descendant RNA molecules