Phylogeny and Systematics Part 6 Phylogeny and Systematics
- Slides: 26
Phylogeny and Systematics (Part 6) Phylogeny and Systematics (Making “Trees of Life”) AP Biology Ms. Day
Macroevolution • studies focus on change that occurs at or above the level of species ▫ The origin of taxonomic groups higher than species level How does this occur? • Evolution of new traits (novelties) • mass extinctions • Open adaptive zones (divergent evolution)
Intro to Phylogenetics • https: //highered. mheducation. com/sites/98340 92339/student_view 0/chapter 23/animation__phylogenetic_trees. html
Phylogeny What is phylogeny? • The evolutionary history of a group of organisms • Systematics attempts to reconstruct phylogeny, by analyzing evolutionary relatedness ▫ Use morphological and biochemical similarities • Molecular systematics uses DNA, RNA and proteins to infer evolutionary relatedness. • Different tools are used to reconstruct phylogenies called phylogentic trees.
Making Evolutionary “Trees”: Illustrating Phylogeny 2 Methods 1. Cladistics = BRANCHES NOT TIME RELATED ▫ sorts primitive and shared derived characteristics ▫ based on evolutionary relationships Makes cladograms
Let’s review in groups…
Cladograms have clades • A clade within a cladogram ▫ a group of species that includes an ancestral species and all its descendants • Cladistics ▫ the study of resemblances among clades
Cladistics • Each branch is called a clade https: //www. youtube. com/w atch? v=46 L_2 RI 1 k 3 k
WHY?
2. Phenetics = BRANCHES ARE TIME RELATED ▫ based on overall similarity (morphology) without regard for evolutionary relationships based on how similar organisms look REMEMER: Organisms can develop similar features through converent evolution **Creates phylograms
• Each branch point ▫ Represents the divergence of two species Leopard Domestic cat Common ancestor
• “Deeper” branch points ▫ Represent progressively greater amounts of divergence; more closely related Wolf Leopard Common ancestor Domestic cat
More changes here length of a branch reflects # of genetic changes that have taken place in a particular DNA sequence in that lineage
• Currently, scientists use ▫ Morphological (anatomy), biochemical, and molecular comparisons to show evolutionary relationships in “trees” Obtained through fossil studies, DNA technology and current organisms
Molecular systematics
Not all Similarities Represent Common Ancestry • Homologous structures indicate shared common ancestry ▫ Homologous structures are therefore evidence of divergent evolution • Analogous structures are similar in function but not in evolutionary history ▫ Analogous structures are evidence of convergent evolution It is not always easy to sort homologous from analogous structures
Analogous Structures
How to Make a Trees: Hypotheses
• https: //ccl. northwestern. edu/simevolution/obonu/cladogra ms/Open-This-File. swf • A shared primitive character ▫ a homologous structure that is shared by all groups you are trying to define • A shared derived character ▫ A new evolutionary trait unique to a particular clade(s)/branch
Outgroups vs. Ingroups • Outgroup ▫ Species or group of species that is closely related to the ingroup ▫ Distinguishes between shared primitive and shared derived characteristics ▫ Closely related to ingroup • Ingroup ▫ the various species we are studying
A Cladogram What is the shared primitive characteristic? Notochord
• http: //www. cengage. com/biology/discipline_co ntent/animations/cladogram_construction. html • http: //www. wwnorton. com/college/biology/evo lution/ch/04/animations. aspx
Phylograms and cladograms trees are JUST hypotheses Which is the most parsimonious tree? • the best hypothesis which requires fewest evolutionary changes Parsimony does not always work, nature does not always take the simplest course
- Systematics vs taxonomy
- 0110001101
- Traditional systematics
- Systematics deals with
- Section 2 modern classification
- Chapter 26 campbell biology
- Chapter 20 phylogeny and the tree of life
- Monophyletic paraphyletic polyphyletic
- Homologies
- Chapter 26 phylogeny and the tree of life
- Chapter 26 phylogeny and the tree of life
- Rooted vs unrooted phylogenetic tree
- What is an outgroup in a cladogram
- What is a sister group in phylogeny
- Larvacea
- Crab cladogram
- Classification system in biology
- Basal taxon definition biology
- Kingdom animalia cladogram
- What is a mammal
- Symplesiomorphy
- Monophyletic group
- Phylum platyhelminthes
- Metazoan phylogeny
- Amniota
- Dinosauria
- Ap biology phylogeny