13_Lecture_Presentation

Introduction to Evolutionary Biology

• Historical Context of Malaria

  • In the 1960s, WHO aimed to eradicate malaria through DDT spraying.
  • Mosquito populations developed resistance to DDT, complicating eradication efforts.
  • Malaria remains a significant health issue, causing over 1 million deaths annually.

• Evolution of Parasite Resistance

  • Chloroquine, once a miracle drug for malaria, became ineffective due to parasite resistance.
  • Understanding evolution is crucial across biology, from molecular life to ecosystems.

Darwin's Theory of Evolution

• Darwin's Influence

  • Charles Darwin, in "On the Origin of Species by Means of Natural Selection," revolutionized biology.
  • His theory contrasted the view of a young, unchanging Earth populated by static species.

• Concept of Descent with Modification

  • All species are linked through common ancestry.
  • Adaptations arise over time in response to changing environments.

• Darwin's Theory as a Scientific Theory

  • A theory is a comprehensive explanation supported by substantial evidence and capable of generating hypotheses.

Evidence for Evolution

• Fossil Record

  • Fossils serve as imprints/remains of past organisms, highlighting species differences and showing extinction.
  • The fossil record illustrates the evolutionary sequence of organisms over time.

• Transitional Fossils

  • Transitional fossils link extinct species with current ones (e.g., whales and their ancestors).
  • Discoveries like Pakicetus and Rodhocetus strengthened understanding of whale evolution.

• Homology

  • Homologous structures reveal evolutionary relationships among related species.
  • Vestigial structures indicate remnants of significant features in ancestors.

Mechanisms of Evolution

• Natural Selection

  • Natural selection explains how traits favorable for survival and reproduction increase in frequency.
  • Observational evidence of natural selection has been recorded extensively in various species (e.g., pesticide resistance).

• Genetic Variability and Evolution

  • Mutation serves as the source of genetic variation.
  • Sexual reproduction provides varied combinations of alleles.

• Evolutionary Population Dynamics

  • A population is a group of individuals that interbreed. Changes within these populations can lead to evolution.

• Hardy-Weinberg Principle

  • The Hardy-Weinberg equilibrium asserts that allele frequencies remain constant under specific conditions (large population, random mating, etc.).
  • This principle can be tested to determine if evolutionary changes are occurring.

Microevolution and Selection

• Causes of Microevolution

  • Major factors include natural selection, genetic drift, and gene flow.
  • The bottleneck effect reduces diversity due to population shrinkage.
  • The founder effect occurs when a small group colonizes a new area, leading to genetic drift.

• Natural Selection Types

  • Three selection types affect phenotypes: stabilizing (favoring average traits), directional (favoring one extreme), and disruptive (favoring both extremes).

• Sexual Selection

  • This form of natural selection enhances traits that attract mates, influencing sexual dimorphism.

Public Health and Evolution

• Antibiotic Resistance

  • Similar to pesticide resistance, antibiotics select for resistant bacteria, creating public health challenges.
  • Understanding these dynamics is critical in addressing drug resistant infections in society.

• Genetic Variation Preservation

  • Mechanisms like diploidy maintain variation in populations.
  • Heterozygote advantage can reinforce genetic diversity.