Phylogeny, Systematics, And The Tree Of Life

Front 1

clade

Back 1

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

Front 2

cladistics

Back 2

The analysis of the resemblances among clades, or groups of species that share a common ancestor

Front 3

cladogram

Back 3

A diagram depicting patterns of shared characteristics among taxa

Front 4

in-group

Back 4

In a cladistic study of evolutionary relationships among taxa of organisms, the group of taxa that is actually being analyzed

Front 5

maximum parsimony

Back 5

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

Front 6

molecular clock

Back 6

An evolutionary timing method based on the observation that at least some regions of genomes evolve at constant rates

Front 7

molecular systematics

Back 7

The comparison of nucleic acids or other molecules in different species to infer relatedness

Front 8

monophyletic

Back 8

Pertaining to a taxon derived from a single ancestral species that gave rise to no species in any other taxa

Front 9

out-group

Back 9

A species or group of species that is closely related to the group of species being studied, but clearly not as closely related as any study-group members are to each other

Front 10

paraphyletic

Back 10

Pertaining to a taxon that excludes some members that share a common ancestor with members included in the taxon

Front 11

phylogenetic tree

Back 11

A branching diagram that represents a hypothesis about evolutionary relationships

Front 12

phylogeny

Back 12

The evolutionary history of a species or group of related species

Front 13

phylogram

Back 13

A phylogenetic tree in which the lengths of the branches reflect the number of genetic changes that have taken place in a particular DNA or RNA sequence in the various lineages

Front 14

phylum

Back 14

In classification, the taxonomic category above class

Front 15

polyphyletic

Back 15

Pertaining to a taxon whose members were derived from two or more ancestral forms not common to all members

Front 16

shared derived character

Back 16

An evolutionary novelty unique to a particular clade

Front 17

shared primitive character

Back 17

A character displayed in species outside a particular taxon

Front 18

systematics

Back 18

The analytical study of the diversity and relationships of organisms, both present-day and extinct

Front 19

taxon

Back 19

(plural, taxa) The named taxonomic unit at any given level

Front 20

taxonomy

Back 20

A set of characteristics used to assess the similarities and differences between various species, leading to a classification scheme; the branch of biology concerned with naming and classifying the diverse forms of life

Front 21

ultrametric tree

Back 21

A phylogenetic tree in which the lengths of the branches reflect measurements of geologic time

Front 22

geologic record

Back 22

The division of Earth’s history into periods, grouped into five eras: Archaean, Proterozoic, Paleozoic, Mesozoic, and Cenozoic. The periods in the Cenozoic era are further divided into epochs

Front 23

half-life

Back 23

The number of years it takes for 50% of an original sample of an isotope to decay

Front 24

Pangaea

Back 24

The supercontinent formed near the end of the Paleozoic era when plate movements brought all the landmasses of Earth together

Front 25

protobiont

Back 25

An aggregate of abiotically produced molecules surrounded by a membrane or membrane-like structure

Front 26

radiometric dating

Back 26

A method paleontologists use for determining the ages of rocks and fossils on a scale of absolute time, based on the half-life of radioactive isotopes

Front 27

ribozyme

Back 27

An enzymatic RNA molecule that catalyzes reactions during RNA splicing

Front 28

serial endosymbiosis

Back 28

A model of the origin of eukaryotes that proposes that mitochondria, chloroplasts, and perhaps other cellular structures were formerly small prokaryotes that lived symbiotically inside larger cells

Front 29

snowball Earth

Back 29

The hypothesis that glaciers covered the planet’s landmasses from pole to pole 750–570 million years ago

Front 30

stromatolite

Back 30

A fossilized bacterial mat. Some stromatolites were formed 3.5 billion years ago

Front 31

three-domain system

Back 31

A system of taxonomic classification based on three basic groups: Bacteria, Archaea, and Eukarya

Front 32

prokaryote

Back 32

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea

Front 33

eukaryote

Back 33

A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles, present in protists, plants, fungi, and animals; also called eukaryote

Front 34

spontaneous generation

Back 34

The incorrect notion that life can emerge from inanimate material

Front 35

Eukarya

Back 35

The domain that includes all eukaryotic organisms

Front 36

aerobic

Back 36

Containing oxygen; referring to an organism, environment, or cellular process that requires oxygen

Front 37

anaerobic

Back 37

Lacking oxygen; referring to an organism, environment, or cellular process that lacks oxygen and may be poisoned by it

Front 38

Archaea

Back 38

One of two prokaryotic domains, the other being Bacteria

Front 39

Bacteria

Back 39

One of two prokaryotic domains, the other being Archaea

Front 40

Endosymbiotic theory

Back 40

concerns the origins of mitochondria and plastids (e.g. chloroplasts), which are organelles of eukaryotic cells. According to this theory, these organelles originated as separate prokaryotic organisms that were taken inside the cell as endosymbionts. Mitochondria developed from proteobacteria (in particular, Rickettsiales or close relatives) and chloroplasts from cyanobacteria

Front 41

Era

Back 41

a major division of geological time, usually divided into two or more periods

Front 42

Epoch

Back 42

a unit of geological time that is a subdivision of a period and is itself divided into ages

Front 43

Period

Back 43

an amount of time, subdivision of an era

Front 44

mass extinctions

Back 44

sharp decrease in the number of species in a relatively short period of time, caused by an extinction of an unusually large number of species in a short period or a sharp drop in the rate of speciation

Front 45

plate tectonics

Back 45

the large-scale movement of tectonic plates (folding and faulting) that contributes to continental drift

Front 46

biodiversity

Back 46

the diversity of plant and animal life in a particular region

Front 47

binomial nomenclature

Back 47

The scientific system of naming each species of organism with a Latinized name in two parts; the first is the genus, and is written with an initial capital letter; the second is some specific epithet that distinguishes the species within the genus; By convention, the whole name is typeset in italics

Front 48

scientific name

Back 48

The Latin name of genus and species of an organism