Phylogeny Flashcards
Module 1 (Lecture 4)
The origin and diversification of any taxon, or the
evolutionary history of its origin and diversification
Phylogeny
A tree diagram showing the hypothesized evolutionary history between different organisms
Phylogenetic tree
Which letter indicates the most recent
common ancestor of all tetrapods?
A.
B.
C.
D.
C
How are these relationships (Phylogenies) determined?
Phylogenies are inferred from morphological and
molecular characteristics
Character similarity resulting from common ancestry
Homology
Non-homologous due to convergent evolution (i.e. not
inherited from a common ancestor)
Analogy
Bird and bat wings are an example of what?
Analogy
They both permit flight, but evolved separately
Bird and bat forelimbs
are an example of what?
Homology
Originate from a common ancestor
An approach or methodology for classifying organisms
based on common evolutionary descent
Cladistics
What is the goal of cladistics?
To infer the evolutionary tree (phylogeny) that relates
all extant and extinct species
How is Cladistics Accomplished?
Accomplishe by comparing characters
* Characters can be morphological, chromosomal or molecular
* Sometimes behavioural and ecological features are also used
What is used to create a Cladogram?
Analysis of ancestral and derived characters
A diagram used in cladistics to show evolutionary
relationships between organisms
Cladogram
A unit of evolutionary common descent that includes ancestral
lineage and all descendants
Clade
Organismal feature that varies between species
Character
Character state present in the common ancestor
Ancestral Character
All other variant forms of the character that aroselater within the group
Derived Character
What are three types of Clades?
Monophyletic, Paraphyletic, Polyphyletic
Includes the most
recent common ancestor and all descendants
of that ancestor
Monophyletic
Includes the most recent common ancestor and some but not all descendants of that ancestor
Paraphyletic
Does not include the most recent common ancestor of all members of a group. i.e. the group has at least two separate evolutionary origins
Polyphyletic
What Clade does this image represent?
Monophyletic
What Clade does this image represent?
Paraphyletic
What Clade does this image represent?
Polyphyletic
Unicellular eukaryotes (Protits) are a _______ Grouping
Paraphyletic
What are Protista?
A grouping of unicellular eukaryotes
Protista Include…
Protozoa (first animals): animal-like unicellular eukaryotes
Protophyta (fist plants): plant-like unicellular eukaryotes (mostly
algae)
Fungus-like slime molds
True or False
Protists are a monophyletic grouping
False
Once considered to be a phylum
BUT
No longer recognized as a valid clade (i.e. not
monophyletic)
A node on a phylogeny where more than two lineages descend from a single common ancestor
Polytomy
What does Polytomy often indicate?
We don’t know the relationships between the descendent lineages
Descendent lineages speciated simultaneously
