Chapter 26: Phylogeny And The Tree Of Life

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analogy

Back 1

Similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait.

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Animalia

Back 2

The kingdom that consists of multicellular eukaryotes that ingest their food.

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Archaea

Back 3

One of two prokaryotic domains, the other being Bacteria.

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archaean

Back 4

Member of the prokaryotic domain Archaea.

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binomial

Back 5

The two-part latinized name of a species, consisting of the genus and specific epithet.

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branch point

Back 6

The representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor. Most branch points are shown as dichotomies, in which a branch representing the ancestral lineage splits (at the branch point) into two branches, one for each of the two descendant taxa.

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carnivore

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An animal that mainly eats other animals.

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clade

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A group of species that includes an ancestral species and all its descendants.

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cladistics

Back 9

An approach to systematics in which organisms are placed into groups called clades based primarily on common descent.

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class

Back 10

In classification, the taxonomic category above the level of order.

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Eukarya

Back 11

The domain that includes all eukaryotic organisms.

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family

Back 12

In classification, the taxonomic category above genus.

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genome

Back 13

The genetic material of an organism or virus

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genus

Back 14

A taxonomic category above the species level, designated by the first word of a species’ two-part scientific name.

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homoplasy

Back 15

Similar (analogous) structure or molecular sequence that has evolved independently in two species.

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horizontal gene transfer

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The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.

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ingroup

Back 17

A species or group of species whose evolutionary relationships we seek to determine.

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kingdom

Back 18

A taxonomic category, the second broadest after domain.

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maximum likelihood

Back 19

As applied to systematics, a principle that states that when considering multiple phylogenetic hypotheses, one should take into account the hypothesis that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time.

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maximum parsimony

Back 20

A principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.

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molecular clock

Back 21

A method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes appear to evolve at constant rates.

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molecular systematics

Back 22

A scientific discipline that uses nucleic acids or other molecules in different species to infer evolutionary relationships.

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monophyletic

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Pertaining to a group of taxa that consists of a common ancestor and all its descendants. A monophyletic taxon is equivalent to a clade.

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neutral theory

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The hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection.

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orthologous genes

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Homologous genes that are found in different species because of speciation.

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outgroup

Back 26

A species or group of species from an evolutionary lineage that is known to have diverged before the lineage that contains the group of species being studied. An outgroup is selected so that its members are closely related to the group of species being studied, but not as closely related as any study-group members are to each other.

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paralogous genes

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Homologous genes that are found in the same genome as a result of gene duplication.

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paraphyletic

Back 28

Pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants.

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phylocode

Back 29

System of classification of organisms based on evolutionary relationships: Only groups that include a common ancestor and all of its descendents are named.

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phylogenetic bracketing

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An approach in which features shared by two groups of organisms are predicted (by parsimony) to be present in their common ancestor and all of its descendants.

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phylogenetic tree

Back 31

A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.

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phylogeny

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The evolutionary history of a species or group of related species.

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phylum

Back 33

In classification, the taxonomic category above class.

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Plantae

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The kingdom that consists of multicellular eukaryotes that carry out photosynthesis.

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polyphyletic

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Pertaining to a group of taxa derived from two or more different ancestors.

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polytomy

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In a phylogenetic tree, a branch point from which more than two descendant taxa emerge. A polytomy indicates that the evolutionary relationships among the descendant taxa are not yet clear.

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rooted

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Describing a phylogenetic tree that contains a branch point (typically, the one farthest to the left) representing the last common ancestor of all taxa in the tre

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shared ancestral character

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A character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade.

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shared derived character

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An evolutionary novelty that is unique to a particular clade.

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sister taxa

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Groups of organisms that share an immediate common ancestor and hence are each other’s closest relatives.

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systematics

Back 41

A scientific discipline focused on classifying organisms and determining their evolutionary relationships.

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taxon

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A named taxonomic unit at any given level of classification.

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taxonomy

Back 43

A scientific discipline concerned with naming and classifying the diverse forms of life.

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analog

Back 44

proportion (analogy: similarity due to convergence)

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bi

Back 45

two

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nom

Back 46

name (binomial: a two-part latinized name of a species)

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clado

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branch (cladogram: a dichotomous phylogenetic tree that branches repeatedly)

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homo

Back 48

like, resembling (homology: similarity in characteristics resulting from a shared ancestry)

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mono

Back 49

one (monophyletic: pertaining to a taxon derived from a single ancestral species that gave rise to no species in any other taxa)

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parsi

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few (principle of parsimony: the premise that a theory about nature should be the simplest explanation that is consistent with the facts)

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phylo

Back 51

tribe