Lecture Exam 3 Study Notes

Discussion Points:
- Evolution of behavior
- Problems with ancient DNA:
  - Contamination: Presence of modern DNA in samples.
  - Degraded DNA: Challenges in recovering usable sequences.
  - Solutions used in past studies include:
    - Improved extraction techniques
    - Use of PCR (Polymerase Chain Reaction) for amplification.
- Revolutions in Research through PCR:
  - Enables amplification of minute quantities of DNA.
  - Facilitates studies on ancient organisms.
- Conditions for DNA Preservation:
  - Cold, dry conditions typically favor preservation.
  - Anoxic environments (absence of oxygen) help reduce degradation.

Biological Species Concept:
- Definition: Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.
Phylogenetic Species Concept:
- Definition: Species is defined as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.
Limitations of Species Concepts:
- No single species concept fits all situations due to variability in reproductive isolation and evolutionary contexts.
- Examples:
  - Biological species concept less applicable to asexual organisms.
  - Phylogenetic species concept may struggle with recently diverged or morphologically similar species.

Defined: Geographic separation leads to speciation.
Evidence Supporting:
- Distribution patterns of species across geographic barriers.
- Vicariance events (geologic events causing separation).
Vicariance: Definition - The process where species distributions change due to new barriers.
Founder Effect Speciation:
- Defined: New species arise when small populations colonize new environments.
- Evidence: Genetic divergence observed in isolated populations.
- Issues with the genetic mechanism proposed by Ernst Mayr.

Process: New species form within the same geographic area, typically requiring genetic mechanisms to prevent recombination.
Examples of Sympatric Speciation:
- Apple maggot flies diversifying on different hosts.
- Arctic charr variably adapted in an Icelandic lake.
- Cichlids in Lake Apoyo showing ecological diversification.
- Kentia and curly palms exhibiting morphological differences.
Requirements for Evidence:
- Genetic proof to confirm sympatric origin versus allopatric origin.

Defined: Speciation occurring in neighboring populations with limited interbreeding.
Example:
- Sweet vernal grass adapting to heavy metal soils leading to distinct populations.

Autopolyploid Speciation: Formation of new species from a single species through genome duplication.
Allopolyploid Speciation: Combining the genomes of two different species; results in new hybrid species.
- Facilitated by certain properties of plants, leading to higher prevalence of polyploidy in plants than animals.
Animal Examples: Some stick insects and snails have allopolyploid species.

Definition: The process where two or more species evolve in response to one another.
Application: Understanding coevolution’s implications in human health, particularly regarding drug resistance in pathogens like cholera and TB.

Genetic Drift: Random changes in allele frequencies, which are more pronounced in smaller populations.
Genetic Bottleneck: A sharp reduction in population size leading to reduced genetic diversity.
Founder Effect: Genetic differences arising from a small group starting a new population.
Hardy-Weinberg Equilibrium:
- Conditions for equilibrium:
  - No mutations
  - Random mating
  - No natural selection
  - Large population size
  - No gene flow
- Significance of equilibrium: Indicates no evolution occurring in the population.

Pre-mating Isolation Barriers: Prevent organisms from mating due to differences in
- Timing (temporal isolation)
- Behavior (behavioral isolation)
- Habitat (ecological isolation)
Post-mating Isolation Barriers: Affects the viability or fertility of offspring after mating has occurred.
- Examples include hybrid sterility, as observed in mules.

Focus on understanding definitions and examples for each key concept.
Be able to explain the significance of theoretical frameworks and real-world applications in evolutionary biology.
Familiarize yourself with specific case studies discussed in class to illustrate concepts where applicable.