[GE CLST 70B] - Midterm Exam Guide - Comprehensive Notes for the exam (25 pages long!)

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UCLA
GE CLST 70B
MIDTERM EXAM
STUDY GUIDE
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Lecture 1
Evolution
Change through time
Microevolution: changes in gene frequencies in a population
Macroevolution: descent with modification
o The accumulation of microevolutions over long periods of time
Natural Selection
Mechanism for biological evolution
Individuals vary within a population
More individuals produced than can survive
Variation influences survival and reproduction
Variation is heritable
Some Key Points
Evolution is both random (mutations) and nonrandom (selection)
Evolution works on populations, not individuals
Evolution is genetic @ the basic level, changes gene pool
Adaptations: characters selected for in particular environments
If the premises are met, evolution will happen
Ecology and Evolution
Ecology: interactions of organisms with each other and the environment
o links organisms thru flow of energy
Evolution = reaction to ecology
Evolution gives depth of time to ecology
o links organisms via genetics + shared ancestry
Evidence
Direct observation
Comparative anatomy
Classification
Comparative genomics
Fossil record/Paleontology
Biogeography
Embryology/Development
Aquatic Mammals
Fully aquatic: manatees, cetaceans
Partially aquatic: otters, beavers, seals
Cetacea: whales, dolphins, and porpoises
Cetaceans
Cetacean skeletal structure shows terrestrial ancestry
o Skeleton of fins look like human hand, dog paw, bat wing, etc.
Mesonychia: possible ancestral group to whales, wolf-like with hooves
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Cetaceans' closest living relatives based on genetics = hippos
Discovery of distinctive artiodactyl anklebone in cetacean ancestor fossil
Cetaceans evolved from artiodactyls
Transitional forms (intermediate organisms): cross between seal and crocodile
o Ambulocetus
o Pakicetus
Hooved wolves -> crocodile seals -> cetaceans
Unique cetacean characters
o Blow hole
o Reduced pelvis and hind limbs
o Echolocation
o Anklebone
Based on O18/O16 ratios in fossilized bones, we can tell if cetacean ancestors lived in fresh or salt
water
Over time, the ancestors moved from land -> fresh water -> salt water
Comparative Anatomy
Study of similarities and differences in morphology
Homology: derived from a common ancestor
o Not always obviously similar in form
o i.e. mammalian forelimbs
Analogy: similar in form, but not derived from a common ancestor
o Convergent evolution
o i.e. bat wings and bug wings
o i.e. cetacean bodies and fish bodies
Classification/Taxonomy
System invented by Carl Linnaeus, who thought it was evidence of God's plan
Turns out it was actually evolution
Taxonomic hierarchy: organisms are united into groups based on shared characteristics
Smaller groups (species, genus) share a more recent common ancestor
Class mammalia -> order carnivora -> family felidae -> genus lynx -> species L.rufus
Comparative Genomics
Simple genetic code = same for all organisms
Closely related organisms share more genes
Genes that tell an embryo were to put various body parts are the same amongst all organisms that
have those body parts
o i.e. head, limbs, etc.
Fossil Record
Most extinct fossils can be classified into groups of existing organisms
Share similarities due to descent with modification
Difference between living + extinct become greater over time
Organisms living during any one period of earth's history are usually intermediate forms between
earlier and later organisms
Vestigial Structures
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