Lecture 1 - Intermediate Zoology

• Zoology is the study of animal life.
• • Biology is the study of living organisms.
  • Zoology focuses on the Kingdom Animalia.
• Scientific Method

  This simplified flow diagram of the scientific method shows the important components involved in a scientific study.
• Two major paradigms that guide

  zoological research:

  1. Darwin’s Theory of Evolution
  2. The Chromosomal Theory of Inheritance
• Theory of Evolution

  Charles Darwin – On the Origin of Species by Means of Natural Selection, 1859.
• Theory of Evolution

  Five related theories:

  • Perpetual change
  • Common descent
  • Multiplication of species
  • Gradualism
  • Natural selection
• Perpetual Change – The world and the organisms living in it are always changing.
• Common Descent – All forms of life descended from a common ancestor through a branching of lineages.
• Life’s history has the structure of a branching evolutionary tree, known as a phylogeny.
• Multiplication of Species – New species are produced by the splitting and transforming of older species.
• Gradualism – Large differences result from the accumulation of small changes over long periods of time.

  • Occasionally, changes can happen more quickly.
• Natural Selection – Differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment.
• Adaptation results when the most favorable variants accumulate over evolutionary time.
• Natural selection explains why organisms are constructed to meet the demands of their environments.
• Gregor Mendel performed experiments on

  garden peas leading to an understanding of how chromosomal inheritance works.
• Animals originated in the Precambrian seas over 600 million years ago.
• The Cambrian explosion marks the

  earliest fossil appearance of all major groups of living animals plus some groups that are only known from fossils.
• Characteristics of Animals:

  • Eukaryotes: cells contain membrane-enclosed nuclei.
  • Heterotrophs: Not capable of manufacturing their own food and must rely on external food sources.
  • Cells lack cell walls
• Evolutionary History of Animals

  • Choanoflagellates are solitary or colonial protozoans with a flagellum surrounded by a collar of microvilli.
• Choanoflagellates resemble sponge feeding

  cells (choanocytes).
• Colonial Flagellate Hypothesis – metazoans descended from ancestors characterized by a hollow, spherical colony of flagellated cells.
• Syncitial Ciliate Hypothesis – metazoans arose from an ancestor shared with single celled ciliates.