Chapter 26 - Phylogeny and the Tree of Life Flashcards
Phylogeny -
the evolutionary history of a species or group of species
Systematics -
a discipline focused on classifying organisms and determining their evolutionary relationships
Genus (plural, genera)
the first part of a binomial, containing species that appear to be closely related
Specific epithet (species) -
unique for each species within a genus
The Linnaean system -
related genera in the same family, families into orders, orders into classes, classes into phyla (phylum), phyla into kingdoms, and, more recently, kingdoms into domains
Taxon -
named group at any level of the hierarchy (ex. Panthera is a ____ at the genus level, and Mammalia is a ____ at the class level)
Phylogenetic tree -
the evolutionary history of a group of organisms can be represented in a branching diagram
a phylogenetic tree represents a ________ about evolutionary relationships
hypothesis
Branch point -
represents the common ancestor of the two evolutionary lineages diverging from it
An evolutionary lineage -
sequence of ancestral organisms leading to a particular descendant taxon
Sister taxa -
groups of organisms that share an immediate common ancestor that is not shared by any other group
Basal taxon -
a lineage that diverges from all other members of its group early in the history of the group
Rooted -
which means that a branch point within the tree (often drawn farthest to the left) represents the most recent common ancestor of all taxa in the tree
Phylogenetic trees:
intend to show patterns of descent, not phenotypic similarity; cannot necessarily show the ages of the taxa or branch points shown in a tree
Homologies -
phenotypic and genetic similarities due to shared ancestry are called …
Analogy
similarity between organisms that is due to convergent evolution
Homology -
similarity between organisms that is due to shared ancestry
Convergent evolution -
occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages
If genes in two organisms share many portions of their nucleotide sequences, it is likely that the genes are __________
Two sequences that resemble each other at many points along their length most likely are __________
homologous; homologous
Cladistics -
an approach to systematics where common ancestry is the primary criterion used to classify organisms
Clades -
groups where each of which includes an ancestral species and all of its descendants
Monophyletic taxon -
consists of an ancestral species and all of its descendants
Paraphyletic taxon -
consists of an ancestral species and some, but not all, of its descendants
Polyphyletic taxon -
includes distantly related species but does not include their most recent common ancestor
Shared ancestral character -
a character that originated in an ancestor of the taxon
Shared derived character -
an evolutionary novelty unique to a clade
An outgroup -
is a species or group of species from an evolutionary lineage that is closely related to but not part of the group of species that we are studying
An ingroup -
the species or group of species from an evolutionary lineage that is being studied
By comparing members of the ______ with each other and with the _______, we can determine which characters were derived at the various branch points of vertebrate evolution
ingroup; outgroup
Principle of maximum parsimony -
according to _______ we should first investigate the simplest explanation that is consistent with the facts
In the case of trees based on morphology, the most parsimonious tree requires the fewest _________ __________.
evolutionary events
For phylogenies based on DNA, the most parsimonious tree requires the fewest ______ _______.
base changes
Maximum likelihood approach -
identifies the tree most likely to have produced a given set of DNA data based on certain probability rules about how DNA sequences change over time
Orthologous genes -
where the homology is the result of a speciation event and hence occurs between genes found in different species
can only diverge after speciation has taken place, that is, after the genes are found in separate gene pools
Paralogous genes -
where the homology results from gene duplication; hence, multiple copies of these genes have diverged from one another within a species
can diverge within a species because they are present in more than one copy in the genome
Molecular clock -
an approach for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates
Molecular clock example: the number of nucleotide substitutions in _______ _______ is proportional to the time that has elapsed since the genes branched from their common ancestor.
orthologous genes (ex.)
Molecular clock example: the number of substitutions is proportional to the time since the ancestral gene was duplicated in ________ _____
paralogous genes (ex.)
Selectively neutral -
neither beneficial nor detrimental
Differences in the ______ _____ for different genes are related to how important a gene is
clock rate
The five kingdoms: This system highlighted the two fundamentally different types of cells, prokaryotic and eukaryotic, and set the prokaryotes apart from all eukaryotes by placing them in their own kingdom, Monera
Monera (prokaryotes), Protista (a diverse kingdom consisting mostly of unicellular organisms), Plantae, Fungi, and Animalia
Domain Bacteria -
contains most of the currently known prokaryotes
Monera -
kingdom of prokaryotes
Protista -
a diverse kingdom consisting mostly of unicellular organisms
Domain Archaea -
consists of a diverse group of prokaryotic organisms
Domain Eukarya -
consists of all the organisms that have cells containing true nuclei
Horizontal gene transfer -
a process in which genes are transferred from one genome to another through mechanisms such as exchange of transposable elements and plasmids, viral infection, and fusions of organisms
