Lecture 2 - Tree of life and biodiversity Flashcards
What is phylogeny?
Relationship between organisms
Visual representation of the evolutionary history of populations, genes or species
What are the 3 types of evidence to construct phylogeny?
Morphology
Molecular evidence
Fossils
What are homoplastic traits?
Traits that are similar for reasons other than inheritance from a common ancestor
What are synapomorphies?
Derived form of a trait shared by a group of related species
Shared derived characteristics
How is molecular evidence used to construct a phylogeny tree?
Take DNA of modern animals and compare to others to see how similar it is to another animal
Who classified the diversity of life and when did they do it?
Linnaeus
1700s
What are the tips in a phylogenetic tree?
The terminal ends of an evolutionary tree
What are nodes?
Points in a phylogeny where a lineage splits
Branching point
Represents where populations became genetically isolated
What are clades?
Single branches - an organism and all its decedents
All organisms that share a common ancestor
Set of hierarchically nested groups
What is morphology and how is it shown in a phylogenetic tree?
Study of size, shape and structure of organisms
Each own characteristic shows a separate trait
What are characters in the study of evolution?
Heritable aspects that can be compared
What are taxa in the study of evolution?
Group of organisms that form a cohesive taxonomic unit
What is homology?
Similarity of traits in different species resulting from their inheritance from a common ancestor
What is the first principle of phylogenetic inference?
Assumes similar features are…
homologous until shown otherwise
What is the second principle of phylogenetic inference?
Doesn’t use shared ancestral features but..
uses shared derived features
What are autapomorphies?
Unique morphological features
Do not provide useful grouping information
Why might microorganisms share genes?
Due to horizontal gene transfer
Where genetic material other than other than from parents to offspring is transferred to another organism
When was Darwin’s theory of evolution?
1859
What can phylogeny be used for?
Used to identify source of viruses
Date of disease onset
Track viral evolution
Identify modes of potential transmission
Organize knowledge of diversity
How do you know if organisms are more closely related in a phylogenetic tree?
Taxa that diverged from each other more recently
Have more character states in common
How can timing be estimated within phylogeny?
Combing phylogenetic morphological evidence with fossils
What are branches?
Lineages evolving connecting other branching events
What are internal nodes?
Occur within phylogeny, represent ancestral populations or species
What is a cladogram?
When phylogenetic tree shows only relationship among species
