Phylogenetic Trees Organizing Nature

Clarification  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 Groups  Make 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 Basics Y-axis = time (roughly with no exact scale) 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 4Species 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 4Species 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 3Species 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 2Species 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!!!

Practice What species is most closely related to the Corsac fox? A. Kit foxB. Red fox C. Rupelle’s foxD. B and C equally Which species is most distantly related to the Bat- eared fox? A. Raccoon DogB. Fennec fox C. Short-eared DogD. 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 4Species 3 Species 2 -Trait C originates Should be found in species 4 only

Example Which 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