BIOL 1202 : Test 2
February 17, 2012- CHAPTER 26
PHYLGENY & SYSTEMATICS
• 5 kingdom classification system in use through the late 1900s:
o Monera
o Protista
o Plantae
o Fungi
o Animalia
o Think of it as every species on the Earth will be placed into “5 different levels in the
library”
o Protista, plantae, fungi, and animalia are now put into the “Eukarya” section of the
three-domain system used today
o Monera is now bacteria and archaea
• 3 domain system used today:
o Bacteria
o Archaea
o Eukarya
o These three origins all originated from the 5 kingdom classification system
• There are 5 different kingdoms which are put into the domain system:
o Bacteria
▪ Bacterial kingdom
o Archaea
▪ Archaea domain
o “Protistan,” plantae, fungi, animalia
▪ Eukarya domain
• Taxon (taxa: plural):
o Hierarchical classification system
o The named taxonomic units at any level in this taxonomic hierarchy
o “Did King Phil Come Over For Gumbo Sunday?”
o Most inclusive:
▪ Domain
o Least inclusive
▪ Species
o Example: Panthera = genus pardus = specific epithet
▪ You must include both in the name
• Linnaeus convinced us to use a hierarchical classification system
• Darwin provided us with the mechanism by which evolution results in descent with modification
• These two ideas brought together:
o Taxonomy
▪ Naming & classifying organisms
▪ By using this classification system, you can make a Family Tree of Life
o Systematics
▪ Naming & classifying organisms according to their evolutionary relationships
o Phylogenetics
▪ Reconstructing the evolutionary relationship among organisms
o Combination of systematics and phylogenetics is Systematic Phylogenetics
MACROEVOLUTION & PHYLOGENY
• Phylogenetic tree:
o Hypothesized genealogy traced back to the last common ancestor (i.e., the most recent)
through hierarchical, dichotomous branching
▪ Dichotomous means “two branches” splitting one to two
o Example:
▪ Domestic cat, leopard, and wolf
▪ Shows that the cat and leopard share a common ancestor
• Cladistics:
o The principles that guide the production of phylogenetic trees, a.k.a., cladograms
• Node:
o Branch point in the phylogenetic tree with speciation occurs
• Lineage:
o Entire branch
• Clade:
o Monophyletic group, i.e., an ancestral species and all of its descendants
• Taxonomic groups often reflect true clades
• The fossil record is especially valuable, and the only option for many extinct taxa
o If you have a 100 million year old fossil, and then today, the fossil record allows us to fill
in the middle to connect the two parts (beginning & end)
• Cladistic principles allow us to construct hypothesized phylogenetic trees
o Cladistic allows us to look at common ancestry
CLADISTIC ANALYSIS
• Fossils provide morphological data for extinct species, whereas comparison of multiple types of
traits, including molecular, do so for extant species
• Similar characters (e.g., morphological, behavioral, molecular, etc. traits or features) suggest
relatedness
• But, not all similarity derives from common ancestry
• Convergent evolution:
o Can produce superficially similar traits that lack homology with one another
• Homologous characters share common ancestry
o All species that share common characteristics look different today because of divergent
evolution
• Lack of similarity among taxa results from divergence
• Analogous characters do not share common ancestry
o If there are similarities among taxa, it results from convergence
• As a general rule, the more homologous characters shared by two species, the more closely they
are related
• Sequences of DNA & RNA (nucleotides) and proteins (amino acids) are used as characters; as a
general rule, the more recently two species shared a common ancestor, the more similar their
sequences
• Each nucleotide can be treated as your character
• Character changes (mutations) from the ancestral to the dericed state include:
o Substitutions
▪ …AGCTCTAGG…
▪ …AGCTATAGG…
o Insertions
▪ …AGCTCTAGG…
▪ …AGCTGATCTAGG
o Deletions
▪ …AGCTCTAGG…
▪ …AGCTCTGG…
• All similar characters
• Analogies Homologies
• Shared primitive characters (ancestral) &
shared derived characters (unique to a clade)
• The sequence of branching in a cladogram then represents the sequence in which evolutionary
novelties (shared derived characters) evolved
• Ingroup vs. Outgroup
o Figure 26.11
o Ingroup: the group whose relationships we are trying to resolve
o Outgroup: a species (or group) known to have an older most recent common ancestor
with the ingroup than the ingroup’s most recent common ancestor
▪ Does not share any common characteristics compared to the ingroup
• An outgroup helps identify shared ancestral and shared derived characters (unique to a clade)
• Parsimony & Occam’s Razor
Document Summary
Lineage: entire branch, clade, monophyletic group, i. e. , an ancestral species and all of its descendants, taxonomic groups often reflect true clades, the fossil record is especially valuable, and the only option for many extinct taxa. Lack of similarity among taxa results from divergence: analogous characters do not share common ancestry. Insertions: agctctagg , agctgatctagg, deletions, agctctagg , agctctgg , all similar characters, analogies. Homologies: the sequence of branching in a cladogram then represents the sequence in which evolutionary, shared primitive characters (ancestral) & shared derived characters (unique to a clade) novelties (shared derived characters) evolved. Sweat/sebaceous glands secreting acids & natural antibiotics like lactic acid: mucous membranes: of respiratory and digestive tracts are well-defined. Pus is dried wbc: figure 43. 9, steps of inflammatory response, 1. Histamine is released, move to the capillaries, and increasing the diameter of the capillaries to increase blood flow: 4. Phagocytes leave capillaries and ingest bacteria and dead cells: fever: response to microbes establishing major infection.
