Lesson 5

• It has been used to construct the evolutionary relationship of life’s diverse forms.


  Systematics
• In recent years, we have gained insight into the very deepest branches of the tree of life through molecular systematics.
• It is the study of the kinds and diversity of organisms and of any and all relationships among them.


  Systematics
• Tracing phylogeny is one of the goals of systematics
• One of the major tasks of systematics is to determine by means of comparison:


  • What the unique properties of each species
  • What higher taxon are.
• It is considered as the study of biological diversity in an evolutionary context.

  Phylogeny
• Systematists use data ranging from:


  • fossils to molecules
  • genes to infer evolutionary relationships.
• Systematics enables biologists to construct a comprehensive tree of life that will continue to be refined as additional data are collected.
• Similar characters due to relatedness.


  HOMOLOGIES
• Homologies can be revealed by:


  • Comparing the AOD (Anatomies of different things)
  • Looking at CSAD (Cellular similarities and differences)
  • Studying ED (embryological development)
  • Studying VSWIO (vestigial structures within individual organisms)
• Studying the embryological development of living things provides clues to the evolution of present-day organisms.


  Embryology/Developmental biology
• It is the geographic distribution of species in time and space as influenced by many factors.


  biogeography
• Lines of evidence to infer evolutionary relationships:


  1. Fossil evidence
  2. Homologies
  3. Embryology/Developmental biology
  4. Biogeography
  5. Molecular clocks help track evolutionary time
• The base sequences of some regions of DNA change at a rate consistent enough to allow dating of episodes in past evolution.


  Molecular clocks help track evolutionary time
• Other genes change in a less predictable way.


  Molecular clocks help track evolutionary time
• Each leaf has a very different shape and function, yet derived from a common ancestral form.

  Homologies
• The forelimb of tetrapods (vertebrates with legs) which all share the same set of bones - the humerus, the radius, and the ulna. These are the same bones seen in fossils of the extinct transitional animal, Eusthenopteron, which demonstrates their common ancestry.


  Homologies
• Organisms that are closely related to one another share many anatomical similarities.

  Homologies
• Factors such as Continental Drift and long-distance dispersal are under Biogeography
• Classification is linked to Phylogeny
• Biologists use phylogenetic trees for many purposes, including:


  1. Testing hypotheses about evolution
  2. Learning about the characteristics of ES (Extinct Species) and AL (Ancestral lineages)
  3. Classifying organisms
• The connection between classification and phylogeny is that hierarchical classification is reflected in the progressively finer branching of phylogenetic trees.
• The branching patterns in some cases match the hierarchical classification of groups nested within more inclusive groups.
• In other situations, however, certain similarities among organisms may lead taxonomists to place a species within a group of organisms (for example genus or family) other than the group to which it is closely related.
• If systematists conclude that such mistake has occurred, the organism may be reclassified (that is placed in a different genus or family) to accurately reflect its evolutionary history.
• It can reflect the branching patterns of phylogenetic trees.


  Hierarchical classification
• This tree traces possible evolutionary relationships between some of the taxa within order Carnivora.


  Tree of life/Phylogenetic trees
• a branch of class Mammalia.


  Carnivora
• What does branch point 1 represent?

  Most recent common ancestor of all members of the weasel (Mustelidae) and dog (Canidae) families

  
• What does branch point 2 represent?


  the most recent common ancestor of coyotes and gray wolves

  
• A major part of systematics that includes description, identification, nomenclature and classification


  Taxonomy
• Taxonomy includes:

  1. description
  2. identification
  3. nomenclature
  4. classification
• It is the connecting classification to phylogeny.


  Systematics
• It is the evolutionary history of a species or a group of related species.

  Phylogeny
• A method of grouping organisms.


  Classification
• It arranges entities into some type of order to provide a system for cataloguing and expressing relationships between these entities.


  Classification
• A system of organizing groups into ranks according to status


  Hierarchy
• It puts groups at various levels according to importance or power.


  Hierarchy
• It is the formal naming of taxa according to some standardized system.


  Nomenclature
• They provide rules for naming several species of plants, fungi, and algae.


  International Code of Botanical Nomenclature (ICBN)