Evolution and Natural Selection Quiz

Phylogenetic Trees

• Phylogenetic trees illustrate common ancestry, aiding treatment development.

Evolution of Drug Resistance

• Bacterial mutations lead to antibiotic resistance.

Evolution

• Evolution explains living things' diversity using DNA sequences, proteins, biochemical pathways, embryological development, anatomy, behavior, life histories, species interactions, and fossils.

Time Scales of Evolutionary Changes

• Microevolution occurs at the population level over short time scales.
• Macroevolution occurs at the species level over long time scales.

Proximate vs. Ultimate Causes

• Proximate causes are immediate mechanisms underlying a behavior.
• Ultimate causes are past conditions leading to encoded DNA information.

What is Evolution?

• Evolution is descent with modification (Darwin).
• Biological evolution is inherited change in organism groups across generations.

Early Evolutionary Biologists

• Early farmers practiced artificial selection, choosing cows for higher milk production.
• Aristotle was a great naturalist and zoologist.
  • Classified species based on observation.
  • Used comparative anatomy.
  • Noted correlations in anatomy.
  • Believed species were fixed, permanent, unalterable, and eternal.
• Al-Jahiz (781-868/9 AD) understood survival of the fittest and interconnected organisms, including food chains.
• Linnaeus developed binomial nomenclature and classified species.
• Lamarck proposed a theory of species change.
  • Species evolved gradually toward increased complexity along a single lineage.
  • Changes occurred due to environmental pressures.

Darwin's Voyage

• Darwin didn't develop his adaptation theory during his voyage.
• Tortoise and finch variations were pointed out by the vice governor, not noticed by Darwin initially.
• Observed organism appearances, not mechanisms.
• Two tortoise adaptations existed in different habitats/diets (southern/dome shell). Correlated, but not proven causal relationships.

Darwin vs. Lamarck

• Darwin proposed that species diverge from a common ancestor with natural selection as the driving force.

Darwin and Wallace

• One main obstacle to Darwin's theory was the model of inheritance, where parental fluids blended in offspring. Mendel's views, opposed to blending idea of inheritance, proposed traits transmitted directly from parents to offspring.

Natural Selection

• Darwin's Logic:
  • Fact 1: Species have high fertility, leading to exponential population growth.
  • Fact 2: Populations remain stable, with minor fluctuations.
  • Fact 3: Natural resources are limited.
  • Inference 1: A struggle for existence occurs, with only some offspring surviving.
  • Inference 2: Survival is not random; inherits traits from survivors.
  • Fact 4: Variation in individuals in a population.
  • Fact 5: Much of this variation is heritable.
  • Inference 3: Natural selection leads to gradual population change and evolution.

Evidence for Evolution

• All life descended from a few common ancestors.
• Species sharing a common ancestor resemble each other.
• Species evolve from pre-existing species, not creation or spontaneous generation.

Components of Natural Selection

• Inheritance: Offspring inherit traits.
• Differential reproductive success: Traits that help individuals survive and reproduce are more frequent.
• Variation: Individuals vary.
• Genotype: Genetic constitution of an organism.
• Phenotype: Physical manifestation of an organism (or part of it) influenced by genotypes.

Genetic Diversity

• Independent assortment of chromosomes during meiosis.
• Crossing over: Exchange of chromosome parts during meiosis.
• Mutation: Changes in DNA or chromosomes, occurring randomly.

Variation Due to Mutation

• Mutations introduce new variation.
• Occur randomly, independently of selection needs.
• Natural selection acts on existing genetic variation.

Natural Selection and Genotype/Phenotype

• Natural selection acts on phenotypes, not genotypes.
• Understand interplay between genotypes, phenotypes, and fitness.

Levels of Selection

• Selection acts on genes, cells, individuals, populations, etc. (e.g., selfish genes, transposons).

Fitness

• Fitness is the ability to survive and reproduce.
  • Viability: Probability of survival to reproductive age.
  • Fertility: Average number of offspring that survive.
• Absolute fitness: Average offspring number of a genotype.
• Relative fitness: Average offspring number relative to other genotypes in a population.

Coat Colors (Oldfield Mouse)

• Coat colour is a phenotype influenced by interactions of MC1R, Alpha melanocyte stimulating hormone, and Agouti signal protein.
• Mutations change receptor/activator binding, impacting color polymorphism.
• Coat color influences predator vulnerability and fitness.

Types of Selection

• Frequency-Independent Selection: Directional selection (recessive, codominant, dominant alleles).
• Overdominance: Heterozygote advantage, balancing selection. Underdominance: Heterozygote disadvantage.
• Frequency-Dependent Selection: Positive (trait fitness rises with frequency) and negative (trait fitness rises with decreasing frequency) selection.

Sexual Selection

• Sexual selection improves mating success at the cost of other success factors.
• Males and females differ in interests, leading to sexual conflict.
• Darwin proposed intrasexual (male-male competition) and intersexual (female choice) selection mechanisms.

Sex and Asexual Reproduction

• Advantages of sex include recombination, generating novel genotypes.
• Advantages of asexuality include rapid population increase.
• Disadvantages of sex include reduced relatedness and risks of disease transmission.

The Red Queen Hypothesis

• Sex is advantageous due to faster adaptation – "arms race" against parasites.

Speciation

• Biological species concept: Species have limited or no genetic exchange.
• Speciation is the formation of new species, separated by reproductive isolation. Prezygotic and postzygotic barriers can cause reproductive isolation.
• Allopatric speciation: Physical barriers isolate populations.
• Peripatric speciation: Small population moves to new territory.
• Parapatric speciation: Populations spread into adjacent, but not connected, territories.
• Sympatric speciation: Reproductive isolation without a physical barrier.
• Adaptive radiation: Rapid diversification into ecological niches.

Genome Evolution

• Genome changes include single base pair changes, insertions, deletions, chromosome rearrangements, gene duplications, and horizontal gene transfer.
• Single nucleotide polymorphisms (SNPs) can be synonymous (no change in protein sequence) or non-synonymous (change in protein sequence).
• Gene duplication and loss are contributors to evolution.

Domestication

• Domestication is the process of incorporating wild species into human society for control and breeding.
• This involves a mutualistic co-evolution between humans and domesticates.
• Plant and animal domestication were critical developments in human history.
• Homelands of agriculture were few, with early farmers achieving demographic advantages.
• Domestication can result in changes like smaller brains, reduced senses, and different coat colors.

Population Differentiation and Phylogeography

• Population differentiation: Variation exists between spatially distinct populations.
• Gene flow: Movement of individuals between populations affects gene frequencies.
• FST: Measure of population subdivision (0=no subdivision, 1=all populations different).
• Metapopulation structure: Series of subdivided populations connected by migration.
• Effective population size (Ne): Number of individuals contributing to the next generation (influences diversity).
• Selective sweeps: Linked genes change frequency with selection targets.

Test your knowledge on macroevolution, natural selection, and the contributions of early scientists like Darwin and Aristotle. This quiz covers key concepts such as genetic diversity, mutations, and relative fitness. Challenge yourself and explore the complexities of evolutionary theory.