Biological evolution

  • Fossil Evidence: Transitional forms link ancestral species to whales. Key traits like the astragalus connect fossil artiodactyls to whales.

  • Phylogenetics: Examines relationships among fossil species, whales, and other mammals.

Brief Overview of Evolutionary Biology

  • Artificial Selection: Human-driven trait selection (e.g., domesticated animals).

  • Natural Selection: Examples include antibiotic resistance.

  • Comparative Analysis: Examines traits across species.

  • Sex Ratio Evolution: Study of sex distribution in populations.

Evolution before Darwin

  • Ancient Views: Aristotle’s “ladder of life,” Linnaeus’ taxonomy, and Cuvier/Buffon’s fossil studies.

  • Geology’s Influence: Hutton & Lyell’s uniformitarianism.

  • Lamarck: Proposed inheritance of acquired characteristics.

Charles Darwin

  • Background: Studied geology, influenced by uniformitarianism.

  • Voyage of the Beagle: Observed fossils, environmental change, and Galápagos species divergence.

  • Natural Selection: Inspired by Malthus—overproduction, competition, heritable variation, survival of the fittest.

  • Wallace: Independently conceived natural selection.

Natural Selection in Action

  • Artificial Selection: Dog domestication, genetic variants.

  • Convergent Evolution: Similar traits evolve independently (e.g., eyes).

  • Constraints & Trade-offs: Adaptations have limits (e.g., vision vs. other senses).

  • Coloration: Beach mice experiments link genes (mc1r, asip) to color adaptation.

Life History Evolution

  • Trade-offs: Offspring size vs. number, early vs. late reproduction.

  • Guppy Experiments: Predation affects evolutionary traits, tested via transplantation & common garden experiments.

Adaptation & Selection

  • Units of Selection: Individual vs. group selection (debated by Wynne-Edwards, Maynard Smith, etc.).

  • Multilevel Selection: Examples from ants, yeast-mitochondria competition.

Evolution of Eusociality

  • Examples: Ants, termites, bees.

  • Hypotheses: Haplodiploidy, monogamy, ecological drivers (e.g., fortress defense, life insurance).

Evolution of Disease Virulence

  • Trade-off Hypothesis: Balances transmission and host mortality.

  • Malaria Experiments: Virulence varies by transmission method.

  • Paul Ewald: Waterborne diseases (e.g., cholera) evolve high virulence.

Origin of Life

  • Earliest Evidence: Fossils, chemical signatures.

  • Hypotheses: Heterotrophic vs. chemoautotrophic origins.

  • RNA World: Ribozymes, self-replication, transition to DNA.

  • Early Life: Horizontal gene transfer shaped evolution.

Major Evolutionary Transitions

  • Characteristics: Loss of individual reproduction, specialization, efficiency.

  • Conflict & Cooperation: Genetic factors promoting cooperation.

Evolution of Complex Life

  • Endosymbiosis: Mitochondria evolved from engulfed bacteria.

  • Multicellularity: Yeast & slime mold experiments show cooperation & cheating dynamics.

  • Social Groups: Evolution of hunting, protection, and group living.

Mutualism

  • Types: Reciprocity (vampire bats), partner fidelity (clownfish), partner choice (yucca & moths).

  • Enforcement: Punishment & coercion maintain cooperation.

Evolution of Cancer

  • Natural Selection in Cancer: Tumor cells evolve within hosts.

  • Peto’s Paradox: Large animals (e.g., elephants, whales) resist cancer via TP53 gene duplications.

Introduction to Phylogeny

  • Tree Basics: Clades, monophyly vs. polyphyly, rooting trees.

  • Inference Methods: Parsimony principle, homologous vs. analogous traits.

Comparative Evolutionary Studies

  • Warning Coloration: Poison frogs.

  • Vestigial Traits: Snakes’ limb remnants.

  • Big Cats & Domestic Cats: Phylogenetic relationships & evolution.