Lesson 5. Classification And Phylogeny of Animals Flashcards
The practice of categorizing organisms according to similar features goes back to
Aristotle
What is the goal of Taxonomy?
Produce a formal system for naming and classifying species to illustrate their evolutionary relationships
Taxonomists ask whether the species being classified contains the defining feature of a certain taxonomic group
Classification
Ask whether the characteristics of a species support the hypothesis that it descends from the most recent common ancestor
Systematization
Designed the hierarchical classification system in the 18th century
Carolus Linnaeus
Enumerate the 7 hierarchical classification system
Kingdom
Phylum
Class
Order
Family
Genus
Species
Major groups of organisms
Taxa
Singular for taxa
Taxon
Each rank can be subdivided into additional level of ______
Taxa
System developed by Linnaeus for naming species
Binomial nomenclature
What are the two parts of scientific name
Genus and species
______ are latinized and italicized, only the _______ is capitalized
Names, genus
The goal of __________ is to determine the __________
Systematics, phylogeny
Evolutionary history of a species or group of related species
Phylogeny
Inferred by identifying organismal features, characters, that vary among species
Phylogenies
5 characters of phylogeny
Morphological
Chromosomal
Molecular
Behavioral/ecological
Homology
Shared characters that result from common ancestry
Homologous
Shared characters that are not a result of common ancestry, but of independent evolution of similar characters (they are not homologous)
Homoplasies
Can result from convergent evolution
Homoplasies
Occurs when natural selection, working under similar environmental pressures, produces similar (analogous) adaptations in organisms from different evolutionary lineages
Convergent evolution
When trying to determine evolutionary relationships (phylogeny), we only want to consider _________
Homologous characters
This can create errors
Homoplasies
Focusing on homologous structures, determine when that character arose
Shared primitive and shared derived characteristics
Older characteristics
Primitive
Newer characteristics
Derived
Homologous structure that is older than the branching of a particular clade from other members of that clade
Shared primitive character
It is shared by more than just the taxon
Shared primitive character
Example of this character is mammals that have backbone and vertebrates
Shared primitive character
New evolutionary feature, unique to a particular group
Shared derived character
Example of this character is mammals with/without hair
Shared derived character
Most useful for determining evolutionary relationships
Shared derived character
Form of the character that was present in the common ancestor of group
Ancestral character state
Variation of the character that arose later
Derived character states
Determined by using outgroup comparison
Version of the trait is ancestral
Polarity
Closely related, but not part of the group being examine
Outgroup
One that is found in both the study group and the outgroup
Ancestral character
Found in the study group but not the outgroup
Derived character groups
Groups that share derived characters and form a subset within a larger group
Clades
Unit of common evolutionary descent
Clade
A derived character that is shared by all the members of the clade
Synapomorphy
Using ______________ to define clade will result in a __________________
Synapomorphies, nested hierarchy of clades
Ancestral character states for a taxon are called
Plesiomorphic
Shared ancestral characters that do not provide useful information for forming a nested series of clades
Symplesiomorphies
The nested hierarchy of clades can be shown as a ___________ that is based on _______________
Cladogram
Synapomorphies
Valid scale, consists of the ancestor species and all its descendants
Monophyletic
Consists of an ancestral species and some, but not all of the descendants
Paraphyletic clade
Includes many species that lack a common ancestor
Polyphyletic clade
Cladistics are also called
Phylogenetic systematics
A taxonomic theory that is based on cladograms and all taxa must be monophyletic
Cladistics
Based on common descent and the amount of evolutionary change to rank higher taxa
Traditional evolutionary taxonomy
Sometimes this type of classification includes paraphyletic groupings
Evolutionary taxonomy
Does the paraphyletic arrangement of ape families work on cladistics (true or false)
False because cladistics must be monophyletic
What do you call the humans, chimpanzees, gorillas, and orangutans are now all included together in one monophyletic family
Hominidae
A pair of taxa that are most closely related to each other
Sister group
Sometimes accepts paraphyletic clades
Traditional evolutionary taxonomy
Does not accept paraphyletic clades
Cladistics
Cladistics vs Evolutionary taxonomy:
Both _______ monophyletic clades
Both ________ polyphyletic clades
Accept
Reject
Arrange the living organism where they belong
Taxonomy
