evolutionary thought

• GEORGE CUVIER ON EXTINCTION

  — He demonstrates convincingly that extinctions were real.

  — He studied elephant fossils and other big mammal fossils and discovered they were undeniably distinct and did not belong to any species alive today.

  — He believed that Earth went through sudden changes (catastrophism) which caused the mass extinction of species.
• JEAN BAPTISTE LAMARCK ON EVOLUTION

  — He proposed that the driving force of evolution is the Inheritance of acquired characteristics brought about by the environment.

  — Developed Lamarckism, a theory of evolution based on the principle that acquired characteristics of organism could be transmitted to their offspring.

  — suggests organisms acquire or lose traits based in how much they use them in their lives.

  — Inheritance of Acquired Characteristics
• KARL ERNST VON BAER

  — He discovered the mammalian ovum and notochord.

  • In the field of embryology he established the idea that animal embryos started their development with a common, shared structure and became more distinct looking organisms as they further developed
• GREGOR MENDEL ON GENETICS

  — Father of Genetics. Worked on pea plant breeding

  — He discovered the Fundamental Laws of Inheritance.

  — Formulated two fundamental principles of inheritance:

  1.        Principle of Segregation

  2.        Principle of Independent Assortment

  3.        Law of dominance and uniformity

  — allele (alt version of gene); dominant and recessive

  — genotype (AO); phenotype (Type A)
• Natural selection


  The process through which populations of living organisms adapt and change
• Natural selection


  Contrast to artificial selection or selective breeding (controlled by humans)
• Mutation


  Changes in the structure of the molecules that make up genes, called DNA
• Natural selection


  • Survival of the fittest
  • Organisms with more advantageous traits to survive in an environment are more likely to survive and reproduce, passing their traits to their offspring
  • Over multiple generations, organisms become more adapted for survival and reproduction within their specific environments
• Charles Darwin: 'Formulated the concept of natural selection (nature will select)'
• Charles Darwin wrote the book "On the Origin of Species"
• ERNST HAECKEL ON EMBRYOLOGY

  — German, scientist, explorer

  • Proposed that "ontogeny recapitulates phylogeny", suggesting that on organism’s development pass through the adult stages / forms of its evolutionary history (ancestors) or its phylogeny.

  •This is called the biogenetic law.
• WALLACE AND WEGENER ON BIOGEOGRAPHY

  — helped found the modern science of biogeography (study of how species are scattered across the planet. Simply a record of inheritance.)

  — According to Wallace, species were divided by mountain ranges or other barriers that marked the boundaries of many species, resulting to the current distribution. He called the boundary, the Wallace Line.— Wegener and his theory of plate tectonicshelp to further explain why some fossils are found on different regions orcontinent.
• THOMAS MORGAN ON MODERN GENETICS

  — His work confined that genes are stored in chromosomes inside the cell's nuclei.

  — Discovered crossover phenomenon (which parts of chromosomes trade w each other)

  — His experimental studies with the fruit fly showed that genes are linked in a long line of chromosomes stored in cell's nuclei and are responsible for hereditary characteristics.
• — He believed that when an organism is separated by geography the organism developed different traits.

  — Mayr conceptualized the thought that speciation happens when a species becomes isolated or separated from its main group, leading to emergence of new species with its own unique traits


  Erns Mayr on Speciation
• FRANCIS CRICK AND JAMES WATSON ON DNA STRUCTURE

  — They discovered the structure of DNA and presented its three-dimensional model.

  — Like a spiral staircase, they discovered the structure of DNA as a double helix, with two long helical strands of nucleotides that wound around each other.
• ANALOGOUS STRUCTURE

  — It refers to the similar body structures with same function in unrelated species.
• HOMOLOGOUS STRUCTURE


  — Body structures that are similar in different species due to common ancestry.