Ch. 25 – The History of Life on Earth. Lost Worlds Macroevolution Broad pattern of evolution above...
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Transcript of Ch. 25 – The History of Life on Earth. Lost Worlds Macroevolution Broad pattern of evolution above...
Lost WorldsLost Worlds
Macroevolution• Broad pattern of
evolution above the species levels
• Terrestrial vertebrates
• Mass extinctions• Origin of key
adaptations
Early EarthEarly Earth3.5 billion year old fossils4 main stages:1. Abiotic synthesis of small organic
molecules2. Joins of the small molecules into
macromolecules• Abiotic synthesis of RNA
monomers3. Packaging of molecules into
protocells• Reproduction and metabolism
must be carried out simultaneously
• Vesicles4. Origin of self-replicating molecules
that eventually lead to inheritance• ribozymes
Fossil RecordFossil Record Sedimentary rocks• richest source of fossilsGreat changes in the
kinds of organisms on Earth at different points in time
• Incomplete chronicleDating fossils• relative dating
– compare strata– only relative
• Radiometric dating – assign age in yrs.– Based on radioisotopes
and half life
Fossil RecordFossil Record • Substantial chronicle of
evidence• Phylogeny has a
biogeographical basis in continental drift– spatial distribution of
life• Mammals
– Tetrapods– Mandible bone– Middle ear bones– Mammalian’s teeth
Origin of Single-celled and Multicelled Origin of Single-celled and Multicelled Organisms and Colonization of the LandOrganisms and Colonization of the Land
Geologic record• Three eons
– Archaean– Protozoic– Phanerozoic
•Paleozoic•Mesozoic•Cenozoic
First single celled organisms• Two rich sources for early prokaryote fossils are
stromatolites (fossilized layered microbial mats) and sediments from ancient hydrothermal vent habitats.
• 3.5 billion years ago• Found today in warm, salty bays
Fig. 26.4
• Recent fossil finds from China have produced a diversity of algae and animals from 570 million years ago, including beautifully preserved embryos (SEM).
Fig. 26.7
Photosynthesis and the Oxygen RevolutionPhotosynthesis and the Oxygen Revolution
Oxygen gas• Produced from
photosynthesisFirst Eukaryotes• 2.1 billion years old• Endosymbiotic theory• Serial endosymbiosis
Origin of MulticellularityOrigin of Multicellularity
1.5 billion years agoWhy were they limited
in size until about 535 million years ago?
• Severe ice agesCambrian explosionColonization of Land• 500 million years ago
Speciation and Speciation and Extinction RatesExtinction Rates
Mass Extinctions
• “Big Five” Mass Extinction Events
Speciation and Speciation and Extinction RatesExtinction RatesAdaptive
Radiations• Occurred
after each mass extinction
• Worldwide• Regional
Major Changes in Body Form can Result Major Changes in Body Form can Result from Changes in the Sequences and from Changes in the Sequences and Regulation of Developmental GenesRegulation of Developmental Genes
Heterochrony• Evolutionary
change in the rate or timing of developmental events
Major Changes in Body Form can Result Major Changes in Body Form can Result from Changes in the Sequences and from Changes in the Sequences and Regulation of Developmental GenesRegulation of Developmental Genes
Paedomorphosis• Sexually mature
features may be retained from juvenile structures
Major Changes in Body Form can Result from Major Changes in Body Form can Result from Changes in the Sequences and Regulation of Changes in the Sequences and Regulation of
Developmental GenesDevelopmental Genes
Homeotic genes• Master
regulatory genes• Control the
placement and spatial organization of body parts
• Hox genes– Provide
positional information in an animal embryo
Major Changes in Body Form can Result from Major Changes in Body Form can Result from Changes in the Sequences and Regulation of Changes in the Sequences and Regulation of
Developmental GenesDevelopmental Genes
Evolution of Development• Changes in genes• Changes in gene regulation
Evolution is NOT Goal OrientedEvolution is NOT Goal Oriented
Evolutionary novelties
• Eye– Patch of
pigmented cells– Eyecup– Camera type eye– Eye with
primitive lens– Complex camera
lens-type eye– Still maintain
function of vision
• Exaptations