Evolution

Question 1

Where does evidence for evolution come from?

Answer 1

Paleontology, biogeography, embryology, Comparative anatomy, Molecular biology

Question 2

Darwin’s arguments

Answer 2

Populations posses tons of reproductive potential, population sizes are stable, Resources are limited, Individuals compete to survive, Variation is a thing, much variation is heritable, only the fittest individuals survive, evolution occurs as favorable traits accumulate in the population

Question 3

Stabilizing selection

Answer 3

Selects against the extremes

Question 4

Directional selection

Answer 4

selects for one extreme

Question 5

Disruptive selection

Answer 5

Selects for extremes

Question 6

Sexual selection

Answer 6

Differential mating of males in a population. Example: peacocks, deer/antlers

Question 7

Artificial selection

Answer 7

Directional selection carried out by humans

Question 8

Balanced polymorphism

Answer 8

The maintaining of different phenotypes in one population. This can happen in several ways:

1. Heterozygote advantage, like with sickle cell anaemia vs. malaria
2. Hybrid vigor: when a hybrid is better than either of the two species it came from
3. Frequency dependent selection: When the rarest phenotype has the greatest chance of survival, becomes common, and then is selected against, becomes rare…for example, predators that form a search image for the most common form of their prey.

Question 9

Sources of variation (5)

Answer 9

Mutation, Sexual reproductions, diploidy, outbreeding, balanced polymorphism.

Question 10

Neutral variation

Answer 10

Variation that has no selective value

Question 11

How do humans impact the evolutionary potential of other species?

Answer 11

By creating environments in which monocultures are prevalent (agriculture), and overusing antibiotics, thereby eliminating the types of plants that are susceptible to the antibiotics.

Question 12

Causes of changes in allele frequencies

Answer 12

1. Natural Selection
2. Mutations
3. Gene Flow: movement of individuals between populations
4. Genetic drift: random drift. The founder effect (founder populations) and bottlenecks (for some reason, pop size decreases dramatically, random allele frequencies might have more dominance)
5. Nonrandom mating: when individuals choose their mates based upon their particular traits. Inbreeding (mating with family members) and sexual selection (when females only mate with certain males)

Question 13

Genetic/ Hardy-Weinberg Equilibrium

Answer 13

When the allele frequencies remain constant from generation to generation. There is no evolution at genetic equilibrium.

Question 14

What factors could make there not be genetic/hardy weinberg equilibrium?

Answer 14

1. Natural Selection
2. Mutations
3. Gene Flow: movement of individuals between populations
4. Genetic drift: random drift. The founder effect (founder populations) and bottlenecks (for some reason, pop size decreases dramatically, random allele frequencies might have more dominance)
5. Nonrandom mating: when individuals choose their mates based upon their particular traits. Inbreeding (mating with family members) and sexual selection (when females only mate with certain males)

Question 15

HW equilibrium equations and variables

Answer 15

p (dominant) and q (recessive) are allele values for each allele. Frequencies of homozygotes are psquared and qsquared. Frequency of heterozygotes is 2pq.
p+q=1 (all allele sum to 100%)
psquared + 2pq + qsquared = 1 (all ppl sum up to 100%)

Question 16

Allopatric Speciation

Answer 16

Geographic barrier - reproductive isolation - differential evolution - reproductive barriers - new species

Question 17

Sympatric speciation

Answer 17

The formation of a new species without the presence of geographic barriers.

1. Balanced polymorphism, like in different colored insects who can only mate with other same colored insects bc they’d be eaten on a different substrate.
2. Polyploidy. Polyploid individuals are unable to mate with other individuals because their gametes will have too many chromosomes. This is speciation in one generation
3. Hybridization. Two species mate and form a hybrid zone, which may eventually diverge from both parent species

Question 18

Adaptive Radiation

Answer 18

Occurs when a bunch of different species evolve relatively quickly from the same ancestral species. Happens when the original species is introduced into an area where there are lots of options for colonization. Ex: marsupials, galapagos finches

Question 19

Prezygotic isolating mechanisms

Answer 19

Mechanisms that prevent fertalization in order to maintain reproductive isolation of a species

1. Habitat isolation
2. Temporal isolation: mate/flower @ diff times
3. Behavioral Isolation: one species does not recognize the other as an option
4. Mechanical isolation: physically doesn’t work
5. Gametic isolation: male gametes don’t survive in the environment of the female gametes

Question 20

Postzygotic isolating mechanisms

Answer 20

Mechanisms that prevent the formation of fertile progeny.

1. Hybrid inviability: zygotes die
2. Hybrid Sterility: like mules
3. Hybrid breakdown: hybrids produce offspring that are messed up

Question 21

4 Patterns of evolution

Answer 21

Divergent evolution, convergent evolution, parallel evolution, Coevolution

Question 22

Divergent evolution

Answer 22

Two or more species that originated from the same ancestor and became species through allopatric, sumpatric speciation or adaptive radiation.

Question 23

Convergent evolution

Answer 23

When species have analogous structures because they live in similar environments, not because they have a recent common ancestor. (The two species converged).

Question 24

Parallel evolution

Answer 24

Two related species/lineages that make similar evolutionary changes after their divergence from a common ancestor.

Question 25

Coevolution

Answer 25

tit-for-tat evolution in one species that occurs in response to evolution in another species. Ex: predator prey, pollinators flowering plants.

Question 26

Microevolution vs. Macroevolution

Answer 26

Micro: how populations change from generation to generation and how new species originate
Macro: patterns in groups of related species that have occurred over broad periods of time. Determines phylogeny, two theories.

Question 27

Describe the two arguments about Macroevolution

Answer 27

Phyletic gradualism: speciation occurred over a long period of time as accumulated tiny changes
Punctuated equilibrium: speciation occurred very quickly, punctuating long periods of statis in which there was no evolution.

Question 28

Describe the accepted process for the origin of life

Answer 28

1. The earth/its atmosphere form, 4.6bya
2. Primordial seas (water and minerals) formed
3. Organic molecules were synthesized (miller-eurey)
4. Polymers and self replicating molecules were synthesized. (RNA worlds, rna first. DNA world, dna first)
5. Organic molecules isolated into protobionts(pre-cells)
6. Primitive prokaryokes. 3.9 bya
7. Primitive autotrophic prokaryotes
8. Oxygen/ozone layer form as a result of the autotrophic prokaryotes
9. Eukaryotes form (endosymbiotic theory)

Question 29

What evidence is there for the endosymbiotic theory?

Answer 29

1. Mito and chlor have their own DNA
2. Mito and chlor reproduce separately
3. They look like bacteria