Transcript Genetics and Evolution Ch. 2

Genetics and Evolution Ch. 5
• Selection
Natural vs. artificial
Fitness
Galapagos Finch
Directional, Stabilizing, Disruptive Selection
Polymorphism = several forms of a species in
same habitat
• Microevolution vs. Macroevolution
Microevolution: change in allele frequency
Macroevolution: formation of new species
Field
Assistants
Chesapeake Bay Retrievers=
+
Newfoundland
Water Spaniel
English Peppered Moth
Example
English Peppered Moth Example
Before industrial revolution After industrial revolution
Darwin’s 2 Major Ideas
• Variation within an species
(organisms of the same species do not look
exactly alike)
• Not all the offspring produced survive
(there is a struggle for existence)
Genetics
• Chromosomes are made of DNA
• DNA holds genes
• Different forms of a gene = allele
i.e. brown vs. blue eyes
• Dominant = alleles that cover other alleles
i.e. brown eye allele = B
• Recessive = alleles covered up by other alleles
i.e. blue eye allele = b
• How many alleles for each trait???
2 alleles for each trait!
• Homozygous = your 2 alleles are the same
i.e. BB (what color eyes?)
bb (what color eyes?)
• Heterozygous = your 2 alleles are different
i.e. Bb (what color eyes?)
• Genotype = genetic make-up, what alleles
you have
• Phenotype = appearance, what it looks
like
Macroevolution: formation of new
species
• Allopatric Speciation: formation of new
species due to geographic (physical) barrier
• Sympatric Speciation: formation of new
species due to genetic mutation or
reproductive isolation (although they occur
together)
• Adaptive Radiation: formation of new species
due to new opportunities (niches)
i.e. islands
Origin of Life
• Big Bang Theory: formation of the
universe (20 billion years ago=bya)
• Earth formed 4.5 bya
Crust
• First atmosphere:
Core
hydrogen, water vapor,
carbon monoxide, carbon
dioxide,nitrogen, methane, ammonia
• What is missing??
FREE OXYGEN
Miller Experiment
Inorganic
Molecules
Organic
Molecules
Electricity
(carbohydrates=sugars,
Lipids=fats, proteins,
DNA)
(hydrogen, water
vapor, CO2, CO,
nitrogen, ammonia)
No electricity 3.5 bya, so what could cause a spark?
First life on earth 3.5 bya, prokaryotic cells
Prokaryotic cells
Eukaryotic cells (1.5 bya)
Miller Experiment: the origin of life
Plate Tectonics
Plate Tectonics
• What is it called, when plates move
against each other?
• An earthquake!
• What is it called where the plates meet?
• Earthquake fault
• What earthquake fault do we live near?
• San Andreas Fault
• Earthquake Kit??
Continental Drift
Continental Drift
Pangaea:
continents in one land mass
Laurasia:
Gondwana:
N. America
Europe
Asia
Africa, S. America
Australia, Antarctica,
India
Cenozoic
Mesozoic
Paleozoic
•Quaternary: modern man
•Tertiary: radiation of mammals
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•Cretaceous: mass extinction of dinosaurs
•Jurassic: dinosaurs dominant
•Triassic: first dinosaurs
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•Permian: mass extinction of marine life
•Carboniferous: first reptiles
•Devonian: first amphibians
•Ordovician: first fishes
•Cambrian: marine life abundant
•Precambrian: first life on earth
Past vs. Current Extinction
Past
Current
•Slow
•Natural Causes
•Extinction with
replacement
•Fast
•Human Causes
•Extinction without
replacement