handout 8 Flashcards
Non-living; referring to the physical and chemical properties of an
environment
abiotic
The formation of new species in populations that are geographically
isolated from one another
allopatric speciation
Similarity between two species that is due to convergent evolution
rather than to descent from a common ancestor with the same trait
analogy
In a specified group of organisms, a taxon whose evolutionary lineage
diverged early in the history of the group.
basal taxon
The two-part, latinized format for naming a species, consisting of the
genus and specific epithet
binomial
Definition of a species as a group of populations whose members have
the potential to interbreed in nature and produce viable, fertile offspring,
but do not produce viable, fertile offspring with members of other such
groups.
biological species
concept
The representation on a phylogenetic tree of the divergence of two or
more taxa from a common ancestor; usually shown as a dichotomy in
which a branch representing the ancestral lineage splits into two parts,
one for each of the two descendant lineages
branch point
A relatively brief time in geologic history when many present-day phyla
of animals first appeared in the fossil record. This burst of evolutionary
change occurred about 535-525 million years ago and saw the
emergence of the first large, hard-bodied animals.
Cambrian explosion
An approach to systematics in which organisms are placed into groups
called clades based primarily on common descent.
cladistics
A group of species that includes an ancestral species and all of its
descendants
clade
In Linnaean classification, the taxonomic category above the level of
order
class
(1) A deficiency in a chromosome resulting from the loss of a fragment
through breakage. (2) A mutational loss of one or more nucleotide pairs
from a gene
deletion
A definition of species in terms of ecological niche, the sum of how
members of the species interact with the non-living and living parts of
their environment.
ecological species
concept
The theory that mitochondria and plastids, including chloroplasts,
originated as prokaryotic cells engulfed by an ancestral eukaryotic cell.
The engulfed cell and its host cell then evolved into a single organism
endosymbiont theory
A process in which a unicellular organism (the “host”) engulfs another
cell, which lives within the host cell and ultimately becomes an organelle
in the host cell
endosymbiosis
Evolutionary developmental biology; a field of biology that compares
developmental processes of different multicellular organisms to
understand how these processes have evolved and how changes can
modify existing organismal features or lead to new ones
evo-devo
The division of Earth’s history into time periods, grouped into three eons
– Archaean, Proterozoic, and Phanerozoic – and further subdivided into
eras, periods, and epochs
geologic record
The amount of time it takes for 50% of a sample of a radioactive isotope
to decay
half-life
Evolutionary change in the timing or rate of an organism’s development
heterochrony
An organism that obtains organic food molecules by eating other
organisms or substances derived from them
heterotroph
Any of the master regulatory genes that control placement and spatial
organization of body parts in animals, plants, and fungi by controlling the
developmental fate of groups of cells
homeotic gene
A similar (analogous) structure or molecular sequence that has evolved
independently in two species
homoplasy
Offspring that results from the mating of individuals from two different
species or from two true-breeding varieties of the same species
hybrid
A geographic region in which members of different species meet and
mate, producing at least some offspring of mixed ancestry
hybrid zone
A mutation involving the addition of one or more nucleotide pairs to a
gene
insertion
Evolutionary change above the species level. Examples of change include
the origin of a new group of organisms through a series of speciation
events and the impact of mass extinctions on the diversity of life and its
subsequent recovery
macroevolution
The elimination of a large number of species throughout Earth, the result
of global environmental changes.
mass extinction
As applied to molecular 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
maximum likelihood
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
maximum parsimony
A modified type of cell division in sexually reproducing organisms
consisting of two rounds of cell division but only one round of DNA
replication. It results in cells with half the number of chromosome sets
as the original cell.
meiosis
A process of nuclear division in eukaryotic cells conventionally divided
into five stages: prophase, prometaphase, metaphase, anaphase, and telophase – conserves chromosome number by allocating replicated
chromosomes equally to each of the daughter nuclei.
mitosis
A scientific discipline that uses nucleic acids or other molecules to infer
evolutionary relationships between different species
molecular systematics
Pertaining to a group of taxa that consists of a common ancestor and all
of its descendants – this type of taxon is equivalent to a clade
monophyletic
A definition of species in terms of measurable anatomical criteria
morphological species
concept
In Linnaean classification, the taxonomic category above the level of
family
order
Homologous genes that are found in different species because of
speciation
orthologous genes
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; 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.
outgroup
Homologous genes that are found in the same genome as a result of gene
duplication
paralogous genes
Pertaining to a group of taxa that consists of a common ancestor and
some, but not all, of its descendants
paraphyletic
Proposed system of classification of organisms based on evolutionary
relationships: Only groups that include a common ancestor and all of its
descendants are named.
PhyloCode
A definition of species as the smallest group of individuals that share a
common ancestor, forming one branch on the tree of life
phylogenetic species
concept
A branching diagram that represents a hypothesis about the evolutionary
history of a group of organisms.
phylogenetic tree
The evolutionary history of a species or group of related species
phylogeny
In Linnaean classification, the taxonomic category above class.
phylum
The theory that the continents are part of great plates of Earth’s crust
that float on the hot, underlying portion of the mantle. Movements in
the mantle cause the continents to move slowly over time
plate tectonics
Pertaining to a group of taxa derived from two or more different
ancestors
polyphyletic