CH 20 Phylogeny Flashcards
Who is the founder of modern taxonomy?
Carolus Linnaeus
What is Binomial Nomenclature?
2-part scientific name (being the genus and then the specific epithet)
What is the 1st Part of a binomial nomenclature name?
The Genus
What is the 2nd part of a binomial nomenclature name?
The specific epithet that distinguishes species within a genus
What are the 3 main rules for writing binomial nomenclature names?
-The 1st letter of the genus (1st part of the name) must be capitalized
-The 2nd part of the name can NOT have any capital letters
-The whole name MUST be written in italics, if handwritten underline it instead
What are the Taxonomic Classification Levels? From Greatest (most broad) to least (most specific)
Greatest (Most Broad) –> Least (Most Specific)
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
What is a phylogenetic tree?
the evolutionary history of a species or group of related species
Who was the first to depict the relationship of organisms in a tree-like diagram?
Darwin
Phylogenetic Trees are hypotheses about ____?
Evolutionary Relationships
What are systematics?
a discipline that classifies organisms & determines their evolutionary relationships
What is a taxon?
a taxonomic unit at any level of hierarchy
What is a Branch Point (or Node) ?
a divergence of two taxa from a common ancestor, in short it represents a common ancestor
Sister Taxa are
Closest Ancestors
A rooted tree has a ?
branch representing the most recent common ancestor of all taxa in the tree
What is a Basal Taxon?
early division in a history of group
-also called the OUTGROUP
What is a Polytomy?
a branch that has 3 or more groups emerged
- this is because we don’t know which 2/3 are more closely related resulting in the polytomy
Rooted Phylogenetic tree’s Generally do NOT show what?
*when a divergence occurs
-unlesss, theres a molecular clock at
*how much change occurs in a lineage
-unrooted phylogenetic trees DO
show genetic change through the
length variations in each root
Phylogenies are based on?
homologies
When inferring phylogenies the similarities MUST result from?
Shared ancestry (must homologous, NOT analogous)
What is a homology?
similarities in structure, physiology, or development shared between different species of organisms that share a common ancestor
What is a analogy?
similarities in analogy evolved independently due to convergent evolution, aka from similar habitat/selective pressures
-does not provide information on ancestry!
Phylogenies are inferred from what kind of similarities?
Homologous - phenotypic and genetic similarities from SHARED ANCESTRY!!
Define Cladistic
classifies organisms by common descent
Define Clade
a group of species that includes an ancestral species AND all of its descendants
clades can be nested in larger clades, but not all groupings of organisms qualify as clades
A valid clade must be ?
Monophyletic
-a group of organisms that consists of all known descendants of the groups ancestor (often the ancestor itself is included)
