evolution

Question 1

darwins observation

Answer 1

• Species in Africa should resemble species in Africa, but rather they resemble species in South America
• Influenced by Thomas Malthus: human species populating too much = limited resources
  o Populations of species are constant b/c of death
  o Struggle for existence = species w/ favourable traits survive

Question 2

natural selection

Answer 2

• Those with favourable traits will overtake those with bad traits = evolution
• Increases differences in pops to produce pops suited for their environment
• Lyrell said the earth is old and Darwin used that to explain adaptation and biodiversity over time

Question 3

population and fitness

Answer 3

• Population: local group of potential interbreeding individuals in the same species
  o Defined by gene pool—sum total of alleles of all genes in the population
  o Individual with favourable alleles has a higher chance to survive and interbreed
   Its alleles will be present in next gen in next generation
  o Fitness—rate of production for viable surviving offspring per time

Question 4

hardy weinberg

Answer 4

• The ratio of dominant and recessive alleles is retained from each generation
• HW Equation: freq of alleles in a pop gene pool remain constant
  o p2 + 2pq + q2 = 1
   homozygous AA
   homozygous aa
   heterozygotes Aa

Question 5

HW is true if

Answer 5

• This is true if: gene pool cannot be altered
  1. No mutations
  2. Isolation from other populations
  3. Large pop size
  4. Random mating
  5. No natural selection—alters gene pool

Question 6

microevolution

Answer 6

• Small scale gen-gen change in freq of a pop alleles

Question 7

mutations

Answer 7

o Heritable changes in genotype
o Substitution in chromosome (small to large)
o Spontaneous and random but not w/o purpose
 Not intended for good or bad
o Rate is low

Question 8

genetic drift

Answer 8

o changes in gene pool due to chance
o Bigger pops are not affected
o Determines evolutionary track of small pops

Question 9

gene flow

Answer 9

o Movement of alleles into or out of a pop (immigration or emigration)
o Introduce new alleles or change existing allele frequencies
o Overall effect is to decrease diff between pops
o Can diminish fast with distance

Question 10

founder effect–genetic drift

Answer 10

 Small pop separated by the larger one will not be a genetic rep of the larger one
* Some alleles are overrepresented or may be completely lost
 Small pop increase in size it would have a diff genetic composition from the larger group

Question 11

bottleneck effect–genetic drift

Answer 11

 Pop is reduced in # by a natural event (earthquake)
 Eliminate alleles entirely and some may be overrepresented

Question 12

nonrandom mating

Answer 12

o Purposeful
o Inbreeding occurs in large population
 Self-pollination does not change alleles but genotype frequencies
 Increases freq of homozygotes
 Decrease heterozygotes
o Does not change the frequencies in a pop but affects genotypic freq

Question 13

responses to selection

Answer 13

• Epistasis—one gene affects the phenotypic expression of another gene at another at another locus
• Pleiotropy—one gene affects a # of phenotypic characteristics

Question 14

adaptation

Answer 14

• State of being adjusted to the environment
• Variation in a trait that increases of the individual

Question 15

coevolution

Answer 15

• Populations of 2 or more species interact closely exerts a strong selective force on the other, adjustment result in coevolution

Question 16

biological species concept

Answer 16

group of interbreeding natural pops that are reproductively isolated
o Anything that can breed that gives something sterile, those 2 bred species are separate
o Isolation = species
o Hybridization: crossing of unlike parents
 Hybrids are intermediates from their parents e.g habitats

Question 17

phylogenetic species concept

Answer 17

statistically difference for traits to emerge
o Implies genetic isolation but does not require breeding test or complete genetic isolation to determine the species

Question 18

morphological species concept

Answer 18

o Based on appearance

Question 19

how does speciation occur

Answer 19

allopatric, sympatric, recombination speciation

Question 20

allopatric speciation

Answer 20

o Geographic barrier arises—preventing gene flow from blending away any differences
 Through selection or drift
o Mountains or valleys
o Short distances—accumulation of enough genetic divergence to make a reproductive isolation—infertility or inviability
o Islands have diversification of a group of organisms that have a common ancestor
 Sudden diversification forming a new species with diff ecological roles and adaptation—adaptive radiation

Question 21

sympatric speciation

Answer 21

o Polyploidy—cells that have 2+ sets of chromosomes
 Due to nondisjunction—failure of homologs separating in meiosis
 Due to failure to separate during cytokinesis in miosis

 Autoploidy—doubling of chromosome # within an individual
 Alloploidy—cross b/w two diff species creating an interspecific hybrid (mule)
* Sterile b/c chromosomes did not pair in meiosis
* Daughter has double chromosome as the parent
* Reproductively isolated from the parent
* Chromosome can pair if autoploidy occurs in sterile hybrid the cells can divide in mitosis and produce a new individual asexually

Question 22

asexual reproduction

Answer 22

• Plants can do both (asexual and sexual)
• Asexually produce identical plants quickly and efficiently
• Clones can be useless if diseases fall upon them bc of their lack of genetic diversity i.e. potatoes
• Apomixis
  o Formation of seeds w/ embryos that are produced without fertilization
   Embryos are clones of mother

Question 23

macroevolution

Answer 23

• Discontinuity in habitat and the accumulation of small changes in freq of alleles in gene pools
  o Gradualism model
  o Punctuated model–evolution occurs in spurts instead of following the slow, but steady path

Question 24

recombination speciation

Answer 24

speciation
 Two distinct species hybridize, the mixed genome of the hybrid a third species that is reproductively isolated from the parent species