evolution

Question 1

what is evolution

Answer 1

process of genetic change in a population over time

Question 2

Jean Baptiste Lemarck

Answer 2

-Inheritance of acquired characteristics: passed on to its offsprings
-Use and Disuse: body parts not used would be lost and disappear
-THEROY: giraffe’s long neck
Giraffes stretched necks to eat from tall trees, this trait passed onto generations

Question 3

Charles Darwin

Answer 3

-Travelled on HMS beagle, mapped South American Coast
-Explored regions and collected samples (plants, animals, rocks, fossils) (flora and fauna)
-Some animals of extinct animals looked similar to living animals
-Animals on Galapagos Islands resembled animals observed on South American Coast

Question 4

what is an adaptation

Answer 4

structure, behaviour, or physiological process that helps an organism survive and reproduce in a specific environment

Question 5

structural adaptation

Answer 5

physical features
ex: camouflage, mimicry, webbed feet
- mimicry: resembles a harmful species
- camouflage: allows organisms to blend with surroundings

Question 6

physical adaptation

Answer 6

internal and cellular features that helps them to survive in environment
ex: toxins produced by plants

Question 7

behaviour adaptation

Answer 7

actions of organism that helps them to survive in environment
ex: hibernation, birds migrating south
-hibernation: reduce metabolism to save energy and survive harsh winters
ex: ground hog

Question 8

what is natural selection

Answer 8

process of change in the characteristics of a population of organisms over generations

Question 9

what is artificial selection

Answer 9

describes changes to a population caused by selective breeding by humans
Ex: cats bred for appearance

Question 10

what is sexual selection

Answer 10

natural selection for mating based on competition between males and choices made by females

Question 11

what are some of the historical contributions that led to the idea of evolution

Answer 11

• animals observed on the Galapagos Islands resembled animals observed on the South American coast by Darwin
• discovery of fossil bones from large extinct mammals

Question 12

peppered moth study

Answer 12

• would camouflage in trees covered in lichen, prey for birds
• air pollution from new factories killed the lichen and soot covered the trees
• moths that survived long enough to reproduce were able to pass on genes to their offspring

Question 13

what is a population

Answer 13

consists of all the members of a species that live in an area at a certain time

Question 14

what is allele frequency

Answer 14

number of times an allele occurs in a gene pool compared to the number in the pool for the same gene

Question 15

what is gene flow

Answer 15

net movement of alleles from one population to another

Question 16

what is genetic drift + the two types

Answer 16

changes in allele frequency due to chance events
- FOUNDER EFFECT: individuals start and establish a new isolated population
ex: galapagos islands
- BOTTLENECK EFFECT: change in gene pool resulting from rapid decrease in population size
ex: elephant seals due to overhunting

Question 17

what are the three types of natural selection (know graphs)

Answer 17

1. STABILIZING SELECTION: favours intermediate phenotypes and acts against extreme phenotypes (narrower range)
   - ex: babies birth weight
2. DIRECTIONAL SELECTION: favours phenotypes at one extreme over another, results in shifted range of phenotypes
   - ex: peppered moths
3. DISRUPTIVE SELECTION: favours both extremes rather than intermediate phenotypes, results in split gene pool
   - ex: african finches
   (know graphs for each)

Question 18

analogous vs. homologous structures

Answer 18

ANALOGOUS: similar structure but may have different functions
ex: vertebrate forelimbs in birds, whales
HOMOLOGOUS: similar function but different structures
ex: birds and bats

Question 19

what is speciation
macroevolution vs. microevolution

Answer 19

MACRO: changes occur over long period of time
MICRO: change in gene frequencies within a population over time

Question 20

pre-zygotic mechanisms

Answer 20

prevention of mating
1. BEHAVIOURAL ISOLATION: behaviour that prevents interbreeding with closely related species
- ex: mating rituals
2. HABITAT ISOLATION:s pecies in same area occupy different habitats, rarely encounter each other
- ex: garter snakes in water and meadows
3. TEMPORAL ISOLATION: species kept separate due to timing barriers, mate at different times (seasons, years, etc.)
- ex: flowering
prevention of fertilization
4. MECHANICAL ISOLATION: related species anatomically different, can’t mate
- ex: variations in flower structure prevent pollination
5. GAMETIC ISOLATION: sperm can’t reach or fertilize egg
- ex: plants may land on stigma- fertilization doesn’t occur

Question 21

post-zygotic mechanisms

Answer 21

1. HYBRID INVIABILITY: develops but can’t survive to maturity
   - ex: cotton plants- produce weak and sterile seeds
2. HYBRID INFERTILITY: two species can mate but hybrid is sterile and can’t reproduce
   - ex: horse (female) and donkey (male) -> mule (sterile)
3. ZYGOTE MORTALITY: genetic differences may stop development of zygote
   - ex: sheep and goat hybrids -> fertilization occurs but zygote doesn’t survive

Question 22

allopatric speciation

Answer 22

populations separated by a geographical barrier and diverge genetically
ex: lava flow, water

Question 23

sympatric speciation

Answer 23

populations within same geographical area diverge genetically
ex: polyploidy- results in extra chromosomes due to error in cell division

Question 24

adaptive radiation

Answer 24

diversification of a common ancestral species into a variety of differently adapted species
ex: galapagos islands

Question 25

divergent evolution

Answer 25

occurs when populations adapt to different environmental conditions, diverge and become distinct
- common ancestor
ex: adaptive radiation

Question 26

convergent evolution

Answer 26

occurs when unrelated species occupy similar environments in different parts of the world
- no common ancestor
ex: birds and bats have wings

Question 27

gradualism hypothesis

Answer 27

small, adaptive changes gradually accumulate over time
- fossils rarely reveal gradual transition

Question 28

punctuate equilibrium hypothesis

Answer 28

interrupted by periods of divergence
- supported by fossil evidence