Chapter 19 Flashcards
Taxonomy
The science of the classification of organisms into an ordered system that indicates natural relationships
Binomial Nomenclature
Invented by Linnaeus, the naming of a species with a two-part scientific name, the first part indicating the genus and the second indicating species (often called the specific epithet)
Classification
An arrangement of organisms into hierarchical groups that reflect their relatedness
Taxonomic Hierarchy
Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species. (Diligent Kindly Professors Cannot Often Fail Good Students) Species higher on the hierarchy often have less in common than those at the bottom.
Phylogeny
The evolutionary history of a group of organisms
Phylogenetic Trees
A branching diagram depicting the evolutionary relationships of groups of organisms. Nodes that diverge from a recent common node are more closely related to each other than clades that emerged from an older node. (figure 19.3)
Clade
A monophyletic group of organisms that share homologous features derived from a common ancestor. Sister clades are two evolutionary lineages that emerge from the same node in a phylogenetic tree.
Monophyletic Taxa
Groups of organisms, each of which includes a single ancestral species and all of its decendants
Polyphyletic Taxon
Includes species from different evolutionary lineages. The most recent common ancestor is not included
Paraphyletic Taxon
Includes an ancestral species and only some of its descendants. Some descendants are excluded.
Homology
A characteristic inherited through a genetic basis that indicates that there is some common ancestor.
Convergent Evolution
The evolution of similar adaptations in distinctly related organisms that occupy similar environments.
Homoplasy
When characteristics are shared by a set of species, often because they live in similar environments, but those characteristics are not present in their common ancestor; often the product of convergent evolution.
Behavioural Characters
When external morphology cannot be used to differentiate animal species, systematists often examine behaviours for clues about their relationship.
Molecular Sequences for Phylogenetic Data
Today, most researchers conduct phylogenetic analysis using molecular characters, such as nucleotide base sequences of DNA and RNA.
Traditional Systematics
An approach to systematics that uses phenotypic similarities and differences to infer evolutionary relationships, grouping together species that share both ancestral and derived characters.
Cladistics
An approach to systematics that uses shared derived characters to infer the phylogenetic relationships and evolutionary history of groups of organisms
Ancestral Character State
A trait that was present in a distant common ancestor
Derived Character State
A new version of a trait found in the most recent common ancestor of a group.
Apomorphy
A derived character state (apo = away; morph = form)
Synapomorphy
A derived character state found in two or more species. (syn = together). Presence of synapomorphy among species provides a clue that they may be members of the same clade.
Outgroup Comparison
In the absence of fossil information to provide unambiguous information this technique will be used. Used to identify ancestral and derived characters by comparing the group under study with more distantly related species that are not otherwise included in the analysis.
Parsimony Approach
The philosophical concept of identifying the optimal phylogenetic tree. This principle states that the simplest plausible explanation of any phenomenon is the best.
Maximum likelihood method
A statistical technique that compares alternative phylogenetic trees with specific models of evolutionary change.
Genetic Distance Method
An approach that calculates the overall proportion of nucleotide bases that differ among species.
Molecular Clock
A technique for dating the time of divergence of two species or lineages, based on the number of molecular sequences between them.
