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BILD 3 Lecture 06
Phylogenetics and Systematics
31
Biology
Undergraduate 1
10/24/2010

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Term
Fossil Record
Definition
-based on the sequence in which they have accumulated
-reveal ancestral characteristics that may of been lost over time
-fossil dates provide minimum estimates of the age of a taxon
Term
Morphological and Molecular Homologies
Definition
organisms that share similar morphologies or DNA sequences are likely to be more closely related
Term
Potential source of error in reconstructing relationships
Definition
-due to Convergent evolution (analogy) rather than shared ancestry
Term
Analogous (convergent) characteristics
Definition
-occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages
-evolved independetly
-bat and bird wings
-marsupial mole vs placental mole or Humans vs Kangaroo
-also called homoplasies
Term
Homologus characteristics
Definition
held in common by a group due to shared ancestry
-human, cat, whale, and bat bones
Term
Molecular Homologies
Definition
found using computer programs that separate chance homoplasies, from similarities that imply relationships
Term
Phylogenetic systematics
Definition
connect classification with evolutionary history
-informs the construction of phylogenetic trees on shared homologous characteristics
Term
3 types of phylogenetic trees
Definition
cladograms, phylograms, ultrametric trees
Term
Taxonomy
Definition
ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences
Term
Binomial Nomenclature
Definition
two-part format of the scientific name of an organism
Term
Carolus Linnaeus
Definition
-created binomial nomenclature
-also introduced a system for grouping species in increasingly broad categories (Hierarchical Classification)
Term
List the categories of Taxonomic hierarchy
Definition
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Term
Each branch point of a branching phylogenetic trees represent:
Definition
divergence of two lineages
-deeper branch points represent progressively greater amounts of divergence
Term
Cladogram
Definition
-imply the relative order of divergences of taxa, but provide no information about the amount of change, or the time-depth of various events
-depiction of shared ancestries among taxa
Term
Clade (within cladogram)
Definition
group of species that includes an ancestral species and all its descendants
-can be nested within larger clades, but not all groupings or organisms qualify as clades
-defined by their evolutionary novelties in phylogenetic analysis
Term
Monophyletic group (clade)
Definition
contains the common ancestor and all of its descendants
-only monophyletic groups qualify as legitimate clade
-ex. mammalia, aves, angiosperms, insects, ect.
Term
Paraphyletic group
Definition
contains a common ancestor and some but not all descendants
-ex. dinosaur, fish, gymnosperms
Term
Polyphyletic group
Definition
contains taxa with different ancestors
ex. marine mammals, flying vertebrates, trees
Term
Shared ancestral character
Definition
originated in an ancestor of the taxon or group
Term
Shared derived character
Definition
evolutionary novelty unique to a particular clade
Term
Outgroup
Definition
species or group of species that is closely related to the in-group
Term
Ingroup
Definition
the species being studied
Term
Outgroup comparison
Definition
based on the assumption that homologies present in both the outgrip and in-group must be primitive characters that predate the divergence of both groups from a common ancestor
-helps determine the direction and order of character state change
Term
Phylograms
Definition
length of a branch reflects number of genetic changes that have taken place in a particular DNA or RNA sequence in that lineage
Term
Ultrametric Trees
Definition
branching pattern same as in phylogram, but branch length represents an estimate of time
Term
Principle of Maximum Parsimony
Definition
most parsimonious tree is the one that requires the fewest evolutionary events to have occured
Term
Principle of Maximum Likelihood
Definition
given a certain hypothesis about how DNA changes over time, a tree can be found that maximizes the likelihood of the observed data (this tree reflects most likely sequence of evolutionary events
Term
Linus Pauling
Definition
suggested that rates of molecular change (DNA or amino acid substitution) might be relatively constant among different organisms (Molecular Clocks)
-if so there will be correlation between amount of divergence and time since divergence
Term
Neutral Theory
Definition
evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian selection
-rate of molecular change in these genes and proteins should be like a clock
Term
Origin of HIV
Definition
-Phylogenetic analysis shows that it descended from viruses that infect chimpanzees and other primates
-Bush meat trade usual hypothesis however Hooper suggested that it originated from early polio vaccines since they may have been created using chimpanzee cells
-virus evolved in clocklike fashion
Term
Similar Fish in Africa and South America Possibilities:
Definition
-independent evolution of similar assemblages of fish on each continent
-long-distance dispersal brought similar forms to each continent
-Vicariance (splitting by geographic barrier): separation of the continents yielded split populations
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