Genetics, Evolution, and Biodiversity Exam Notes

Genetics and Inheritance

• Traits are inherited through genes on chromosomes.

• Dominant alleles mask recessive alleles in heterozygotes.

• Punnett squares predict offspring genotypes and phenotypes.

• Mutations can lead to new traits.

• Example: Rabbit fur color (B = black, b = white).

  • Bb x bb cross: 50% black (Bb), 50% white (bb).

• Example: Cat hair length (H = short, h = long).

  • Hh x hh cross: 50% short (Hh), 50% long (hh).

• Tuskless elephants: Mutation lethal in males; dominant in females.

  • Poaching selects for tusklessness.

Genetic Diversity

• Small, isolated populations lose genetic diversity.

• This makes them vulnerable to disease and environmental change.

• Great Lakes wolf population example: debated if large enough to maintain diversity.

Key Genetic Terms

• Allele: Variant of a gene.

• Homozygous: Two identical alleles (e.g., TT, tt).

• Heterozygous: Two different alleles (e.g., Tt).

Evolution and Speciation

• Species relationships are determined by comparative anatomy, DNA, behavior, and fossils.

• Phylogenetic trees model species relatedness; nodes are common ancestors.

• Environmental pressures cause evolutionary changes (e.g., tuskless elephants, antibiotic resistance).

• Evidence for Relatedness:

  • Morphology, behavior, DNA, and fossils are used to classify organisms.

• Phylogenetic Trees:

  • Root: ancient ancestor.

  • Branches: lineages over time.

  • Nodes: speciation events.

Dire Wolf DNA

• Dire wolves not closely related to gray wolves despite similar bone structure.

• Specialization on large prey may have led to extinction.

Elephants’ Future

• Poaching led to increased tuskless females.

• Tuskless females 5x more likely to survive poaching.

Oysters and Shell Thickness

• Shell thickness is an inherited trait.

• Ocean chemistry changes affect shell formation.

• Oysters with thicker shells have an advantage in changing conditions.

Biodiversity and Mass Extinction

• Mass extinction: loss of many species in a short time.

• Biodiversity includes genetic, species, and ecosystem diversity.

• Human activities threaten biodiversity.

Biodiversity Loss and Medicine

• Species loss is 1,000-10,000 times faster than background rate.

• Loss of plant biodiversity limits discovery of new medicines.

• Many medications derived from plants/fungi (e.g., penicillin, morphine).

Maintaining Crop Biodiversity

• Loss of crop diversity affects nutrient-rich diets.

• Crop diversity needed for agricultural resilience and adapting to climate change.

• Gene banks and collaboration with farmers are key for preservation.

Indigenous Knowledge and Conservation

• Traditional ecological knowledge valuable for managing biodiversity loss.

• Ecosystem viewed as a community; biodiversity loss is devastating.

Fishing Regulations and Impacts

• Overfishing leads to endangered species and biodiversity loss.

• Selective fishing practices can unbalance ecosystems.

Climate Change and Biodiversity

• Climate change and biodiversity loss are major concerns.

• Climate mitigation efforts (e.g., tree planting) can harm biodiversity.

• Need to balance climate action with biodiversity conservation.

Species Recovery and Policy

• Species recovery requires measurable criteria: population size, genetic diversity.

• Policy decisions must consider ecological and socioeconomic factors.

• Delisting requires careful evaluation.

Gray Wolf Delisting Debate

• Gray wolves removed from endangered species list in 2020.

• Decision based on population size in Great Lakes and Northern Rocky Mountains.

• Critics question lack of genetic criteria in conservation frameworks.

• Genetic diversity and geographic distribution should be considered.

Key Definitions

• Biodiversity: Variety of life.

• Genetic Diversity: Total number of genetic characteristics in a species.

• Speciation: New species arise.

• Keystone Species: Ecosystem depends on it.

Scientific Argumentation

• Arguments need clear questions, claims, and evidence.

• Claims answer the question.

• Evidence from reliable sources.

• Reasoning explains how evidence supports the claim.

Argument Tool Framework

• Question: Focused, scientific.

• Claim: Testable statement answering the question.

• Support: Evidence (facts, data).

Practice Question: Elephant Population Changes

• Question: How will elephant populations change due to increased tusklessness?

• Claim: Populations will stabilize at reduced numbers, but face long-term risks.

• Evidence:

  • Tuskless trait spread.

  • Genetic consequences (male lethality).

  • Ecological impacts (tusks used for digging).

Practice Questions and Answers:

• Natural selection: Survival and reproduction based on traits.

• Isolation: Separation preventing interbreeding.

• Species: Group that can interbreed and produce fertile offspring.

• Genes: DNA segments for proteins determining traits.

• Alleles: Different versions of a gene.

• Genotype: Complete set of genes.

• Phenotype: Physical expression of a trait.

• Mutation: Change in DNA sequence.

• Biodiversity: Variety of life.

• Mass extinction: Large number of species die out.

• Loss of biodiversity: Ecosystems become weaker.

• Importance of biodiversity: Ecosystem services, food, medicine.

• Animal extinction during mass extinction: Loss of balance, food web disruption, genes/traits.

• Limiting fishing: Prevents population decline and imbalance.

• Interbreeding closely related animals: Reduces genetic diversity, increases harmful traits.

• Genetic diversity is impacted by: Habitat destruction, pollution, and inbreeding reduce genetic diversity leading to vulnerability of populations to diseases and climate change

• Preventing loss of biodiversity: Conserve habitats, reduce pollution, support sustainability. Efforts should include supporting breeding programs with genetic variation, creating wildlife corridors and storing seeds and DNA.

• Preventing mass extinction: Combat climate change, enforce wildlife laws, restore ecosystems.