BIO153_Lecture_4
Page 1: Introduction to Phylogenetic Trees
Lecture Title: Phylogenetic Tree
Course: BIO153 Diversity of Organisms
Instructor: Ichiro Inamoto
Institution: University of Toronto Mississauga
Page 2: Taxonomy and Phylogeny
Taxonomy: Study of organisms; involves naming and grouping related organisms.
Nomenclature: Organizing naming schemes.
Classification: Grouping organisms into similar categories.
Phylogeny: Deduce evolutionary relationships based on classification.
This includes understanding taxonomy in the context of evolutionary biology.
Page 3: Taxonomy and Phylogeny Examples
Examples of Organisms:
Plants: Sycamore maple, Cactus, Fern (Kingdom: Plantae)
Vascular plants have tube-like structures for water transport.
Animals: Elephant, White-tailed deer, Canada lynx (Kingdom: Animalia)
Mammals nurture their young with milk.
Classification is based on evolutionary relationships.
Page 4: Cheetah Classification
Inquiry: Is the Cheetah a cat?
Family Felidae has retractable claws; non-retractable in Canidae (dogs).
Cheetahs (Acinonyx jubatus): Fastest terrestrial animals, can't fully retract claws, adapted for speed.
Questions arise on how to classify based on claw types versus evolutionary relationships.
Page 5: Cladistics Overview
Cladistics: Method for classifying organisms based on ancestral relationships.
Cheetah classified within Family Felidae due to shared ancestry with other cats.
Focus on evolutionary relationships over just anatomical traits.
Page 6: Phylogenetic Trees
Phylogenetic Tree: Visual representation of evolutionary relationships derived from taxonomy and cladistics.
This lecture centers around understanding these trees and their implications for classification.
Page 7: Understanding Phylogenetic Trees
Phylogenetic Tree of Family Felidae: Displays relationships among various cat species.
Includes domestic cat, dogs, cheetah, and other felids.
Page 8: Implications of the Phylogenetic Tree
Hypothesis Nature: Represents evolutionary relationships but may be subject to change with new findings.
Classification can vary based on the traits prioritized in constructing the tree.
Page 9: Basic Features of a Phylogenetic Tree
Branch Point: Indicates divergence from a common ancestor into different species.
Dichotomy: A type of branch point where a single ancestor diverges into two lineages.
Example: Human and Chimpanzee share a common ancestor, diverging at a branch point.
Page 10: Multiple Branch Points
More complex trees show more than one branch point, indicating multiple species.
First branch: Divergence of 'Lizards' from 'Chimpanzee/Human'.
Second branch: Divergence of 'Chimpanzees' from 'Humans'.
Page 11: Sister Taxa Concept
Root: Common ancestor for all taxa in the tree.
Sister Taxa: Two groups sharing a common ancestor that no other group shares, exemplified by Chimpanzees and Humans.
Page 12: Relative Nature of Sister Taxa
Sister Taxa: Depends on the common ancestor selected.
Choosing different common ancestors leads to different interpretations of relationships.
Page 13: Group Clustering
Grouping based on common ancestry allows clustering of Lizard, Chimpanzee, and Human, forming a sister group against other taxa.
Page 14: Sister Taxa Descriptions
Descriptions of sister taxa shift based on which common ancestor is chosen, impacting perceived relationships.
Page 15: Basal Taxon Description
Basal Taxon: Lineage that diverges early in a tree's history, e.g., Fish as the basal group in certain trees.
Page 16: Interpreting Phylogenetic Trees
Property 1: Shows connections without indicating degree of genetic similarity.
Trees can be represented in various shapes without altering meaning.
Page 17: Distinguishing Features in Trees
Different representations maintain the same relationships but may visually differ.
Page 18: Patterns of Descent
Property 2: Patterns of descent do not always align with external similarities in organisms.
Example: Cetaceans (whales/dolphins) are more closely related to hippopotamuses rather than seals despite superficial similarities.
Page 19: Clarifying Evolutionary Relationships
Property 3: Trees do not imply direct evolution from neighboring taxa.
They suggest common ancestry but do not indicate linear evolution, e.g., humans and chimpanzees share a common ancestor rather than one evolving from the other.
Page 20: Cladograms vs. Phylograms
Cladograms: Basic phylogenetic trees showing connections.
Phylograms: Include additional information such as branch length reflecting genetic changes or time.
Page 21: Phylogram Example
Example phylogram detailing the timing of speciation events across millions of years, showcasing how groups diverged over time.
Page 22: Limitations of Phylogenetic Trees
Dichotomy and Polytomy: Speciation events sometimes can't be fully resolved due to data limitations; polytomy indicates unresolved relationships.
Page 23: Image Credits
Attributed sources for images related to organisms and phylogenetic trees, ensuring original contexts and licenses are respected.
Page 24: Image Credits Continued
Additional attributions for sourcing images used throughout the lecture.
Page 25: Image Credits Continued
Continuation of sourced attributions for various images within the presentation.
Page 26: Image Credits Continued
Final set of attributions to conclude the image credit section.