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Classification and phylogeny. Announcements. Assignment from lab 1 is due today in lab Assignment for lab 2 include p23,24,27,28 and MacClade exercise (do it on data from exercise 2). Classification and phylogeny. Concepts and terms Why to study phylogeny

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announcements
Announcements
  • Assignment from lab 1 is due today in lab
  • Assignment for lab 2 include p23,24,27,28 and MacClade exercise (do it on data from exercise 2).
classification and phylogeny1
Classification and phylogeny
  • Concepts and terms
  • Why to study phylogeny
  • Constructing phylogentic tree (cladogram)
  • Classification
  • MacClade
concepts and terms
Concepts and terms
  • Phylogeny.

evolutionary history of a group of organisms (taxa)

  • Systematics

study biological diversity of organisms and their evolution

  • Phylogenetic tree (Cladogram, dendrogram, phylogram).

phylogeny of a group of organisms portrayed in a tree

concepts and terms1
Concepts and terms
  • Classification

attaching names to organisms and group of organisms that may or may not reflect their phylogeny

  • Homology

similarity b/c of having a common origin

  • Analogy

similarity b/c of having a common function

why to study phylogeny
Why to study phylogeny
  • Helps to deal with practical problems
  • Supply us with evolutionary information about -organisms

-traits

-when they evolved and their sequence

-how many time they evolved (happened)

-related species

constructing cladogram
Constructing Cladogram
  • Cladogram in P 15 & P18
  • Derived character (1)

derived (arose) within a group lineage

  • Ancestral character

trait found in common ancestor (0)

  • Outgroup

closely related but outside of the group of interest

  • Tree length

sum of the number of evolutionary steps (events)

constructing cladogram1
Constructing Cladogram

Sister groups

Sister groups

B

A

C

Other

beetles

dimples

Short antennae

Large size

Eye spots on elytra

Modified anal glands

constructing cladogram2
Constructing Cladogram
  • Topology

branching pattern of a phylogenetic tree

  • Characters conflicts due to homoplasy (trait evolved more than once) or evolutionary reversal
  • Cladistic approach (evolutionary path) and Maximum parsimony method (p 18)

minimum number of steps to generate the phylogenetic tree

constructing cladogram3
Constructing Cladogram
  • P 17
  • Monophyletic (clade)

common ancestor with all its descendants

  • Paraphyletic

common ancestor with some but not all its descendants

  • polyphyletic

unconnected species

constructing cladogram4
Constructing Cladogram

Paraphyletic

Monophyletic

polyphyletic

constructing cladogram5
Constructing Cladogram
  • Good character is

1-Variable between species but not within a species

2-Easily measured and unambiguous

3-Shared derived characters is the key for a cladogram

Example: page 23

classification
Classification
  • Taxonomy :grouping and classification of organisms
  • Binominal or linnaean system ( E.coli )
  • Species :group of organisms reproductively isolated from others
  • Genus :group of related species
  • Other categories (kingdom, phylum, class, order, family, genus, species) and any of this is called taxon
what to do
What to do
  • Look for the homologous shared derived character that you can use to construct a clade
  • Try more than one tree shape until you get the most parsimonious
  • Try different topologies (straw model)
exercise 1
Exercise 1

Characters or traits

1-head shape

2-head width

3-tip point

4-head notch

5-spiral thread

6-shank width

7-tight spiral