Unit 4 Flashcards
Phylogenies are an example of what kind of explanation?
Backward-looking
What is a phylogeny?
A visual representation of the genealogical relationships of life, like a family tree (a type of conceptual model)
Phylogenies represent patterns of ____
relationships
Phylogenies depict the evolutionary _____ of species
relatedness
Patterns of lineage splitting are produced by ___
speciation
Speciation on a phylogeny is represent at
the nodes
What are phylogenies used for? (3 examples)
help develop new crops
identify new pathogens that make people sick
conserve endangered species
New traits can appear if
heritable variation originates AND becomes common within a species as a result of evolutionary processes (e.g. speciation)
Taxa (definition)
refers to the units (e.g. species) that we are studying and representing using the phylogeny
The number of taxa we study determines
the number of possible hypothesis
Character (definition)
any feature of an organism
the data we use to generate the phylogeny
Character State (definition)
describes the types of variation (condition) that we observe in our characters
Outgroups (definition)
taxa used to determine the direction, or polarity of character state changes
Parsimony (definition)
defined as “the best solution given the data we have” or “the simplest solution is the best solution”
Used to quantify the quality of each hypothesis using the data
Minimum state change given a data matrix
sum of the minimum number of character state changes for each character (number of characters minus 1)
Consistency index formula
minimum number of changes / tree length
The ___ on a phylogeny represent the location of common ancestors
branches
Phylogenies are read
chronologically (usually bottom to top)
MRCA stands for
most recent common ancestor
Can branches on phylogenies be rotated? Why?
Yes. Evolution does not have a goal or direction. Rotation helps address biases in human thinking
Phylogenies are used to identify hosts of major diseases (T/F)
True.
How are phylogenies used to make predictions about evolution?
They can show how viruses from different people at different times are related to each other
Phylogenies are used to guide the conservation of endangered species (T/F)
True.
Phylogenies are used to accurately name species (T/F)
True.
How are phylogenies used to understand how traits are assembled in a lineage over time?
Use of backward-looking explanations
How can phylogenies help correct “naive” explanations for the presence of biological traits
Phylogenetic thinking highlights ancestry and takes the origins and the history of traits into consideration when explaining the presence of a trait in a living taxon
Naive explanations focus only on
the current function of a trait as it exists today as the PRIMARY explanation for its existence (usually is not the case)
These (7) can be found as fossils
DNA
Hard parts & skeletons
Soft tissues
Proteins + lipids
Footprints + traces
Embryos
Pollen
Which kind of rock do fossils usually occur in?
Sedimentary rock
Phylogenies and the fossil record help to
reveal how characters are assembled in a taxon
reveal stability and change in ecological relationships
understand the role that mass extinctions play in the evolution of life
Background extinction (definition)
typical rates of extinction (very low level)
Mass extinction (definition)
extinction occuring at a significantly higher rate
Main result of mass extinction
major changes in earth systems at rapid rates
Who survives mass extinction?
geographically widespread taxa tend to have lower extinction rates compared to localized taxa
Do factors that impact survival during normal times ensure survival during mass extinction?
No.
The fossil record cannot preserve detailed information about the ecological interactions of species from millions of years ago because behaviors cannot be fossilized (T/F)
False
Phylogenies can be used to identify which processes caused evolutionary change (T/F)
False
The fossil record rarely contains intermediates or “missing links” between different taxa (T/F)
False
Phylogenies cannot be used to determine which evolutionary processes cause the evolutionary relationships among a group of taxa (T/F)
True
Phylogenies are used to test whether the scientific names that taxa have been given reflect the similarity of their physical features (T/F)
False
