BIO120 Test Review

1. living things change over time

2. adaptation arises due to natural selection

What are the two core tenets of evolution?

Heritable variation in fitness

What is natural selection?

1. Experimental

2. Theoretical

3. Observational

4. Comparative

What are the four types of approaches to studying evolution?

Evolutionary history, evolutionary mechanisms

What are the two branches of studying evolution?

1. A phenotypic trait that gives higher relative fitness in a population

2. The processes that allow for the former definition to arise

What are the definitions for Adaptation?

William Paley

Who argued for “The Argument From Design?”

Lemarck

Who argued for “Inheritance of acquired characteristics?”

The idea that the DNA can transfer information to proteins, but never in reverse. It did disprove Lemarck’s idea.

What did August Weissman argue for, and did it disprove Lemarck’s idea?

Charles Darwin and Alfred Russel Wallace

Who came up with the Theory of Natural Selection?

Uniformitarianism and gradualism

What did Lyell discover?

The idea that the process that shaped the earth in previous eons are the same ones that appear today.

Define “Uniformitarianism”

The idea that quickly reproducing organisms are not swelling in population rapidly for some reason or another.

What was it that Malthus wrote about?

Transformational Evolution (Within generations), and Variational Evolution (between generations)

What were the two kinds of evolution that people believed in?

1. There must be variation within a population

2. This variation must be heritable

3. Some organisms confer better fitness in their environment than others

What are the 3 requirements for natural selection to occur?

Brazil: Geology

Galapagos Isles: Biogeography, Homology

Australia: Biogeography

Darwin’s Garden at the Down House: Domestication

What are the four countries and branches where evidence for evolution was found?

Transitional fossils, species linkages, familiar organisms on fresher strata

How did Geology prove evolution?

Vestigial structures (ex. appendix, dysfunctional wings), homologous structures (ex. altered forelimbs), similar gene composition (500 genes shared)

How did Homology prove evolution?

Colonization from cacti, birds, geographical separation leading to diversity within species and early stages of speciation

How did Biogeography prove evolution?

Artificial selection, maize vs. corn, ancestor to present-day changes

How did Domestication prove evolution?

1. Mutations

2. Independent Assortment

3. Recombination

What are the three sources for Genetic Variation?

1. Point mutations

2. “Indels” (Insertions/deletions)

3. Change in repetition #

4. Chromosomal rearrangement/inversion

What are the four kinds of mutations?

They can be beneficial, neutral, or deleterious

How can mutations affect fitness?

True

True or False: A phenotype is a combination of both genetic factors AND environmental ones

True

True or False: Mutation rates can be affected by environment

False

True or False: Mutations are deterministic

Stochastic: Random, unpredictable

Deterministic: Predictable, non-random

Define “Deterministic” and “Stochastic”

Preformationism: Genetic material comes from a single parent

Blending Inheritance: Genes mix together irreversibly, like paint

What were the two types of pre-mendelian ideas of genetics, and how did they work?

Genes are discrete particles

Diploid organisms

Fusion of gametes

What did Mendel conclude?

False, some are continuous

True or False: All phenotypic traits are genotypically discrete

Mendelian genetics (discrete variation (few genes of large effect))
Continuous variation (many small genes)

What are the two modern ideas of genetics?

Fischer, Haldane, Wright

Who made the first mathematical model of evolution?

Mutation - increase

Recombination - increase

Genetic Drift - decrease

Positive/Directional Selection - decrease

Purfying/Negative Selection - decrease

Selection Favouring Diversity - increase

Migration - increase within, decrease between

What are the all of the factors influencing genetic diversity, and do they increase or decrease?

The fraction of a population with a gene containing both possible alleles

Define “Heterozygosity”

Proportion of gene loci containing 2+ alleles within a population

Define “Polymorphism”

Morgan - Classical

Muller - Classical

Ford - Balance

Dobzhansky - Balance

Name the 4 key players of evolutionary schools of thought, and which they followed

High heterozygosity, high polymorphism

Heterozygote Advantage

Selection favours diversity

Define the principles of the balance school

Low heterozygosity, low polymorphism, high homozygosity

“Wild-type” is the normal gene

Negative/purifying selection is predominant

Define the principles of the classical school

Richard Lewontin

Who discovered Electrophoresis?

Motoo Kimura

Negative selection removes deleterious traits, positive selection fixes beneficial ones, the only remaining observable traits for genetic variation are selectively neutral

Who coined the ‘neutral theory’, and what are its tenets?

Analyzed organisms for polymorphism

What did Alivia Dey do?

Note: Remember Parthenogenesis Vs. Clonal Propagation

Fill-in-the-blanks for the tree and its categories

False

True or false: Selfing is a process of asexual organisms

Cost of males

50% of genes from females

Transmission bias for asexuals

Time/energy cost to mate/find mates

Risk of STD, predation

Loss of favourable allele combos

List the costs of sexual reproduction

Fixation of positive genes and elimination of harmful ones

Genetic variation improves survivability of species in unpredictable environments

List the benefits of sexual reproduction

Speed of production

2:3 transmission bias

List the benefits of asexual organisms

Accumulation of deleterious traits

More difficult to remove deleterious traits, slower to fix beneficial ones

More likely to go extinct

List the downsides of asexual organisms

Kin recognition

Different flowering times

Self-incompatibility

Dispersal by sex

Delayed maturation

Extra-pair copulation

What are some methods of inbreeding avoidance?

Increases homozygosity

Decreases heterozygosity

Reduces H by 50% per generation

Inbreeding Depression

What are the consequences of inbreeding?

False, inbreeding DEPRESSION changes allele frequencies

True or False: By itself, inbreeding DOES change allele frequencies

Lower fertility

Lower viability

Homozygosity of deleterious alleles

What are the consequences of inbreeding depression?

Disruptive (creates a bimodal graph, can result in speciation)

Directional (increases/decreases overall mean)

Stabilizing (increases frq. average, decreases outliers)

Three types of GRAPHICAL selection

Environment-Organism correlation: Moth color concentration

Genetic Signatures: Relationship between malaria and anemia gene

Long-Term Experimental Evolution (Richard Lenski): Experiment with citrate and e. coli

Methods of linking evolution to ecology + examples

Gene flow refers to the movement of genes from one population or another, migration is the movement of creatures from one population to another

What is the difference between gene flow and migration?

Gene flow: Against

Selection/drift: Towards

Do gene flow/selection/drift work TOWARDS or AGAINST speciation?

FALSE, it is measured using neutral markers

True or False: Gene flow is measured using beneficial genetic markers

Establish to homozygotic populations with distance, score frequency of heterozygotes, relative estimate of gene flow

How is gene flow measured?

Stochastic: Random, unpredictable forces (Ex. Genetic drift, recombination, mutation)

Deterministic: Predictable (Ex. natural selection)

What are “Stochastic” forces and “Deterministic” forces?

A swift decline in population followed by a rebound that generally causes a loss in diversity

What is a Population Bottleneck?

A small subset of a population is separated by geographic region with a small percentage of variation from previous population

What is a founder event?

Local adaptation, Genetic Drift, Phenotypic plasticity

What are the three causes of phenotypic differentiation?

Reciprocal Transplant Study

Name one way phenotypic plasticity is tested for

When a gene spreads so fast that other genes “hitchhike” and increase in frequency as well

Define “Selective Sweep”

Silent mutation: A mutation that does not affect the genome at all

Missense mutation: A mutation that changes the aminoacid that has mutated

Nonsense mutation: A mutation creating a premature stop codon

What is the difference between a silent mutation, missense mutation, and nonsense mutation?

What are methods of maintaining genetic diversity?

Mutation-selection balance

Selection maintaining variation / balancing selection