Bio 111 Building Phylogenies PDF

Building Phylogenies BIO 111 Student Learning Objectives Define parsimony Apply phylogenies to identify evolutionary relationships  Tim e Nodes represent a speciation event B is more closely related to C than to A. Species that share a more recen...

Building Phylogenies BIO 111 Student Learning Objectives Define parsimony Apply phylogenies to identify evolutionary relationships  Tim e Nodes represent a speciation event B is more closely related to C than to A. Species that share a more recent common ancestor are more closely related than species with a more distant common ancestor. Does not imply “advancement”  Misconceptions Humans did not evolve from chimpanzees. Humans and chimpanzees are evolutionary cousins and share a recent common ancestor that was neither chimpanzee nor human. Humans are not "higher" or "more evolved" than other living lineages. Since our lineages split, humans and chimpanzees have each evolved traits unique to their  How do we determine evolutionary relationships? To infer evolutionary relationships, we compare the traits of species Character - Heritable trait possessed by an organism Character State - One of the possible different conditions of a character Example: - Character: Hair - Character States: "hair present" vs. "hair  How do we determine evolutionary relationships? To infer evolutionary relationships, we compare the traits of species Character - Heritable trait possessed by an organism Character State - One of the possible different conditions of a character Can be morphological, physiological, behavioral, or molecular (DNA sequence, amino acid sequence)  Constructing Phylogenies Parsimony – The most likely explanation is generally the simplest one – Simplest explanation = Least number of changes or steps to construct phylogenetic tree Homology or Homoplasy? ‘Camera’ Eye Parsimony – least number of steps to construct a phylogeny If Homology If Homoplasy Apomorphy derived trait different from ancestral line Synapomorphy Shared derived characters used to group taxa Autapomorphy Unique derived trait Plesiomorphy – characters shared with the outgroup taxa = ancestral character Symplesiomorp hy Ancestral shared trait Constructing a phylogenetic tree 1. Identify apomorphic characters Apomorphy Derived trait Different from ancestral line Constructing a phylogenetic tree 1. Identify apomorphic characters 2. Create a data matrix 3. Estimate evolutionary distance 4. Group by synapomorphies Synapomorphy Shared derived characters used to group taxa Data matrix Constructing a phylogenetic tree 1. Identify apomorphic characters 2. Create a data matrix 3. Estimate evolutionary distance 4. Group by synapomorphies 5. Construct a phylogenetic tree 6. Map the traits onto the tree  Constructing a phylogenetic tree using molecular data DNA sequence, amino acid sequence More characteristics = more data vs. morphological character data Compare homologous nucleotide sequences and whole genome sequences Use molecular synapomorphies  Constructing a phylogenetic tree using molecular data Use molecular synapomorphies  Constructing a phylogenetic tree using molecular data DNA sequence, amino acid sequence More characteristics = more data vs. morphological character data Compare homologous nucleotide sequences and whole genome sequences Use molecular synapomorphies Use overall molecular similarities (distance methods) Amino Acid Sequence Species # of Amino Acids different from Human in Cytochrome C Fruit fly 29 Tuna 21 Pigeon 12 Chimpanze 0 e Frog 18 Rattlesnake 14 Dog 11 Wheat 43 Yeast 45 DNA Sequences – Draw a Tree Differences from Human: Chimpanzee – 3 Orangutan – 5 Cow – 18 Dog – 17 Rat – 20  DNA Sequences – Draw a Differences from Tree Human: Chimpanzee – 3 Orangutan – 5 Cow – 18 Dog – 17 Rat – 20 Hierarchical classification system (taxonomy) should be able to be superimposed on a tree based on shared traits Pitohuis are poisonous birds from New Guinea. There are several species, but we will focus on two: hooded pitohui and crested pitohui. Recent molecular evidence indicates that the hooded pitohui shares a more recent common ancestor with the golden-oriole than with the crested pitohui. The golden-oriole is not poisonous. The chowchilla is an outgroup for the pitohuis and golden-orioles. Chowchilla are poisonous. Hooded PitohuiCrested Pitohui Chowchilla Golden-oriole