phylogenetic trees organizing nature. clarification 7.2 7.3 analyze and make sense of phylogenetic...
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Phylogenetic Trees
Organizing Nature
Clarification
7.2 7.3 Analyze and make
sense of phylogenetic trees E.g. determine
relationships, common ancestry, which traits in each species, which tree fits data
Create phylogenetic trees based on data
Sort the Animals Into GroupsMake as many groups as you choose
Groups are entirely up to you – there’s no right or wrong answer
Be ready to share your groups and reasons for making them
Original Taxonomy – Before Evolution
Group organisms by similar physical characteristics
The Problem Nature is sneaky Sometimes things look really similar But a closer look reveals major differences
Phylogenetic Trees Organize species by evolutionary
relationships Like a family tree
Make groups based on evolutionary origins, not just appearance
How Do We Make Trees?
Finding Common Traits
Comparing DNA/Proteins
Either way – the more traits and genes analyzed, the more accurate the tree becomes.
More simple More accurate
Tree BasicsY-
axis
= t
ime (
roughly
wit
h n
o e
xact
sc
ale
)
Common ancestor of everyone
(Microevolution of that population)
Separation + Divergence
Common ancestor of species 1 and 2
Common ancestor of species 3and 4
Species 1
Species 4
Species 3
Species 2
Notice Species 2 and 3 are NOT closely related. Being
next to each other doesn’t matter
Common ancestor of everyone
Common ancestor of species 1 and 2
Common ancestor of species 3 and 4
Species 1
Species 4
Species 3
Species 2
We could draw this tree like this and it’s the same
Common ancestor of everyone
Common ancestor of species 1 and 2
Common ancestor of species 3 and 4
Species 2
Species 3
Species 4
Species 1
Or Even
Common ancestor of everyone
Common ancestor of species 3 and 4
Common ancestor of species 1 and 2
Species 4
Species 2
Species 1
Species 3
Notes** Tree can go
horizontal as well – same basic idea
Shape of branches may differ (tree vs. cladogram)
Trees often do not show every single descendant – because then they get crazy!!!
PracticeWhat species is most closely related to the Corsac fox?A. Kit fox B. Red foxC. Rupelle’s fox D. B and C equally
Which species is most distantly related to the Bat-eared fox?A. Raccoon Dog B. Fennec foxC. Short-eared Dog D. Artic fox
Trees can also show when traits evolved
Common ancestor of everyone
-Trait A originates
-Trait B originates
Should be found in all 4 species
Should be found in species 3 and 4 only
Species 1
Species 4
Species 3
Species 2
-Trait C originatesShould be found in species 4 only
ExampleWhich species should have vascular tissue and seeds but no flowers?
Which species is most closely related to the pine tree?
Draw another way this tree could look
Photosynthetic Ancestor
Vascular Tissue
Moss
Seeds
Ferns
Flowers
Pine Tree Rose Bush
Pine Trees
Rose Bush
Goal of Modern Phylogeny
Group organisms who are closely related
I.e. are on the same branch
Animals (Kingdom)
Deuterostomes (Superphylum)
Chordata (Phylum)
Vertebrates (Subphylum)
Tetrapods (Superclass)
Mammals (Class)
Marsupials (subclass)
Reptiles
Why Should Birds Be Considered Reptiles?
Rapid Review
Trees show common ancestry
Based on similarities in DNA and anatomy
More recent common ancestor = closer relative
Make groups based on shared common ancestry
7.2.II Reproductive Barriers
Pre-Zygotic
No successful union of sperm and egg
Post-Zygotic
Zygote forms, but the resulting offspring is not fertile and viable
Reproductive Barrier Vine
Short, to-the-point, memorable video Don’t have to use Vine app Maximum of 20 seconds Prepare a 1-2 minute presentation
Explain Vine and how reproductive barrier evolved DUE next class period