shape of plants seed coat Shape of birds bill Characteristic Example/reason Morphology shape of plants seed coat Shape of birds bill Anatomy Number of petals on a flower Type of digestive system in invertebrate Cytology Structure and function of cells Phytochemistry Special organic compounds in plants Chromosome number Two species with same #, more closely related, the differing # of chromosomes Molecular differences Proteins DNA sequences Becoming the norm 5.4 Cladistics

Cladistics. classification that groups taxa Cladistics classification that groups taxa together according to characteristics Natural classification (related based off common descent) Monophyletic: group composed of most recent common ancestor Primitive traits (plesiomorphic) – same structure and function evolved early Derived traits (apomorphic) – same structure and function evolved more recently Determine ‘timeline’ of evolutionary past

Biochemical Evidence Strong link to common ancestry Most life uses left-handed proteins, select few (bacteria) use right-handed Protein structure All living species have same 20 amino acids Can be transferred between organisms DNA sequence All living species using DNA for genetic information Can be spliced between organisms

Phylogeny study of evolutionary past of species Study using: polypeptide sequences of certain proteins Haemoglobin Cytochrome c chlorophyll May support or refute current phylogeny trees – based of observable characteristics More distant relations Closely related

Evolutionary Clock - determined by steady, gradual accumulation of mutations over time Mitochondrial DNA preferable: Only mutations occur Do not go through meiosis therefore no cross-over/random orientation occurring Method: DNA hybridization Match two different DNA strands connection repel Using quantitative biochemical data estimate time of speciation Check fossil evidence, radioisotope dating to confirm

Characteristics used to put species into appropriate clades Homologous structures: common ancestor Analogous structures: not derived from same ancestor

Cladogram – visual representation of evolutionary trends Sister groups: closest relative Clad Outgroup: less related Node: showing common ancestor Primitive characteristics

Cladistics: study of clades find most logical and natural connections between organisms to reveal evolutionary past Working hypothesis: Scientific Lack integrity Feathers? Bird? Difference from Linnaean system Hierarchical groupings unclear at times Birds occupy own class (avian) Several derived characteristics shared with dinosaurs Fused clavicle Flexible wrists Hollow bones Characteristic eggshell Hip/leg structure Parsimony  birds evolved from dinosaurs

Figwort family Plantain family New evidence requires reclassification DNA analysis moved foxglove from figwort to plantain family though morphological features do not match Foxglove

Reclassification of species – rearranges phylogenetic tree Circumscription: place taxa to make monophyletic groups Paraphyletic: species that should be on separate branches Made into monophyletic groups