Evolution and Natural Selection

Question 1

Definitions

Answer 1

• EVOLUTION: “descent w/modifications”; a change in gene frequencies over time; different species evolving via direct common ancestor; requires extinction and relation gaps of gens
• NATURAL SELECTION: the sifting of variation to produce adaptations
• GENETIC DRIFT: random sampling of individuals over time
• FOUNDER EFFECTS: small group of individuals “bud-off”/survive by chance

Question 2

Evolution Evidence

Answer 2

1. FOSSIL RECORD
2. OBSERVATIONS OF SIMILARITIES/DIFFERENCES BETWEEN LIVING SPECIES
3. NATURAL SELECTION WITHIN SPECIES
4. REAL TIME CHANGES

Question 3

EE: Fossil Record

Answer 3

• burgess shale fauna existence; fossils unlike anything today; distinguishes from life theories
• fossil order suggests evolutionary relationships (ie. fish/amphibians/reptiles)
• some species are living fossils (“unchanged” since fossil history began (ie. some dragon lizards)); most known are birds; identical in ancient forms
• INTERMEDIATE: forms present in continuous fossil record

Question 4

EE: Observations of Similarities/Differences Between Living Species

Answer 4

• ANALOGOUS: separate evolutionary patterns being almost identical (ie. inverted vertebrate retinas = non-inverted octopus retina)
• HOMOLOGOUS: a constant evolutionary pattern within species illustrating evolution (ie. pentadactyl limb of tetrapods/bird plumes/foetus structure across mammals)

Question 5

EE-OSD: Vestigial Structures

Answer 5

• pectoral/pelvic articulations in tetrapods = homologous; lost adaptivity, but still visible in skeleton

Question 6

EE-OSD: Phylogenetic Approaches (Example)

Answer 6

WHY ARE SOME BUGS GREEN?

• DATA COLLECTION: morphological/life-history/ecological (ie. edibility/habitat/lifestyle)
• PHYLOGENY BUILD: use molecular data; how similar are species in DNA terms/characteristics (ie. wings/leg length); think family tree
• FIND CHANGES: if a common ancestor has 2 independent relevant changes, why is this (ie. chance move to jungle + body colouration turns to green); 2 changes more likely than 4 = more parsimonious

Question 7

EE-OSD-PA: Problems w/Evolution Classifications Based Externally

Answer 7

1. DISCRIMINATING FEATURES
2. CONVERGENT EVOLUTION:
   - independent evolution of similar features in species; makes analogous structures w/similar form/function but not present in last common ancestor (ie. dolphins and great white sharks (mammals VS fish) leaping similarly)

Question 8

EE-OSD-PA: The Genetic Code

Answer 8

• universal homology
• transcription between base triples in DNA/amino acids/proteins is universal in all life
• PROCESS: some DNA sequences are common in all interest species; compare 1 interest species w/others in terms of links/variations to measure similarity; place most similar together
• selection of unlikely selected regions (ie. neutral/non-coding regions) and assume particular mutation rates, calculation of time since species divergence (mutation count/mutation differences) is possible (aka. dates to divergence patterns)

Question 9

EE-OSD: Phylogenetic Approaches

Answer 9

• what aspects of species’ historical past/current ecology can explain their morphology/behaviour/life history
• relies on most parsimonious pattern of independent changes seem in extant species joined via molecular phylogeny

Question 10

EE: Natural Selection Within Species

Answer 10

• how does variation arise/why are individuals so well adapted environmentally?
• designing agent = SELECTION; shifts beh variants in favour of those which give bearer better rep in next gen

Question 11

EE-NSWS: Variation in Natural Selection

Answer 11

• generated via:
  RANDOM MUTATIONS
  RECOMBINATIONS (VIA SEX)
  GENE FLOW

Question 12

EE-NSWS: Sexual Selection

Answer 12

• selection for reproductive share:
  1. Individuals differ in reproductive outputs
  2. May depend on fecundity (number of possible offspring)/attractiveness (number of possible mates + offspring sum)
• (ie. Birds TM; red birds may have higher fecundity/attractiveness so reproduce more; blue birds may have much lower stats, so less of them in pop; stats can overtake varied 1st gen after breeding season)

Question 13

EE-NSWS: Adaptations

Answer 13

• mostly complex/appearance of design; complexity/evident function cannot arise via random processes (ie. genetic shift)
• natural/sexual selection are only causal mechanisms of evolutionary adaptations making individuals “fitter”

Question 14

EE: Real Time Changes

Answer 14

• evolution can be produced experimentally via natural alterations during domestication (ie. breeding dog breeds)
• modern evolution can be quite recent (ie. moths adapting during Industrial Revolution; grey ones blended into ashen trees around factories while dark ones stood out; dark pop dropped, grey rose)

Question 15

EE: Real Time Changes (Example)

Answer 15

• MULLER (1939); example of evolution of resistance to harmful substances; DDT (dichloro-diphenyl-trichloroethane) killed insects
• BUT before he was even rewarded, evolution of resistance to DDT had already taken place in house flies

Question 16

SUMMARY

Answer 16

• EVOLUTION = “descent w/modification”; powerful tool to understand why extant species behave/look as they do
• evolution requires several evidences strands illustrating operation; explains why extant species are environmentally adapted

Question 17

EE: Extant Species

Answer 17

• can be related to fossil record ancestors
• can be grouped morphologically/behaviourally (careful of analogous features via convergent evolution)
• putative relationships can be confirmed via consideration of universal homologue (DNA) to make phylogenies
• understanding of differences arising via selection WITHIN species, producing adaptations