Processes of Evolution

Question 1

Evolution

Answer 1

the change in genetic composition and makeup of populations over time

Question 2

Evolutionary theory

Answer 2

the understanding of the mechanisms of evolutionary change

Question 3

Darwin’s 3 propositions of theory

Answer 3

• Species change over time
• Divergent species share a common ancestor, and species have diverged gradually through time (descent with modification).
• The mechanism that produces the change is natural selection: the differential survival and reproduction of individuals based on variation in their traits

Question 4

5 processes of evolution

Answer 4

Mutation, gene flow, genetic flow, genetic drift, and nonrandom mating

Question 5

Hardy Weinburg equation

Answer 5

p^2 + 2pq + q^2 = 1, where p^2 = frequency of homozygous dominant genotype, 2pq = frequency of heterozygous genotype, and q^2 = frequency of homozygous recessive genotype

Question 6

Conditions met in the Hardy Weinburg equation

Answer 6

No mutation
No selection among genotypes
No gene flow
Population size is infinite
Mating is random

Question 7

Natural selection can act on quantitative traits in 3 ways:

Answer 7

• Stabilizing selection
• Directional selection
• Disruptive selection

Question 8

Stabilizing selection

Answer 8

preserves the average phenotype

Question 9

Directional selection

Answer 9

favors individuals that vary in 1 direction from the mean

Question 10

Disruptive selection

Answer 10

favors individuals that vary in both directions

Question 11

Trade-offs

Answer 11

result in traits that are adaptive in one context but not another. Ex: rough-skinned newts make the neurotoxin tetrodotoxin (TTX), which paralyzes nerves and muscles.

Question 12

4 eons

Answer 12

• Hadean eon - before life evolved
• Archean eon - early life
• Proterozoic eon - first eukaryotes. First 3 are known collectively as the Precambrian (4 billion years)
• Phanerozoic eon - diversification of eukaryotes.

Question 13

Hadean eon

Answer 13

Earth’s forming: surface is cooling, ocean forms, meteorites, no oxygen, no life

Question 13

Archean eon

Answer 13

atmosphere accumulates, less meteorites, still almost no oxygen, origin of life

Question 13

Impact of weather conditions on Earth

Answer 13

During the Carboniferous and Permian periods, massive burial and decomposition of organic material transformed dead plants and animals into fossil fuels - occurred over millions of years ago. Burning these fossil fuels is releasing that stored carbon as CO2 - occurring over a few hundred years
By 2100, temps are expected to increase by 2-3 degrees C. The last temperatures were that high sea level was 24 meters high

Question 14

Proterozoic eon

Answer 14

origin of photosynthesis, oxygen accumulates from the atmosphere, there’s eukaryotes and multicellular organisms

Question 14

Phanerozoic eon

Answer 14

diversification of eukaryotes, mass extinctions

Question 15

Why do some species go extinct

Answer 15

lack of resources, reproductive partners, no prey = no predators, predators outnumber prey

Question 16

What’s the Cambrian explosion

Answer 16

It is the time when most of the major groups of animals first appear in the fossil record. Soft bodied multicellular organisms began to evolve

Question 17

4 major environmental changes

Answer 17

• Ordovician period - marine organisms occurred and mass glaciers formed
• Devonian period: an extinction at the end of the Devonian resulted in loss of 75% of marine species
• Carboniferous period: large glaciers formed over high latitude, but great swamp forests of horsetails and tree ferns grew on the tropical continents
• Permian period: the continents merged to form the supercontinents Pangaea
• Cretaceous period: modern continents began to form. A continuous sea encircled the tropics. Earth was warm and humid

Question 18

Other important events

Answer 18

• Triassic period: the surviving organisms inhabited a relatively empty world
  Continents began to drift apart; sea levels rose and flooded the continents forming large shallow seas
• Jurassic period: Pangaea divided into Laurasia, which drifted southward
  First lizards and flying reptiles (pterosaurs) appeared; most large terrestrial animals were dinosaurs
• Cretaceous period: modern continents began to form. A continuous sea encircled the tropics. Earth was warm and humid
• Paleogene period: Amphibians, snakes, lizards, birds, and mammals underwent extensive radiations
• Neogene period: continents began to take their current positions