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
A chromosomal alteration in which the organism possesses more than
two complete chromosome sets. It is the result of an accident of cell
division
polyploidy
In a phylogenetic tree, a branch point from which more than two
descendant taxa emerge; indicates that the evolutionary relationships
between the descendant taxa are not yet clear.
polytomy
An abiotic precursor of a living cell that had a membrane-like structure
and that maintained an internal chemistry different from that of its
surroundings.
protocell
In the fossil record, long periods of apparent stasis, in which a species
undergoes little or no morphological change, interrupted by relatively
brief periods of sudden change
punctuated equilibria
A method for determining the absolute age of rocks and fossils, based on
the half-life of radioactive isotopes
radiometric dating
The existence of biological factors (barriers) that impede members of
two species from producing viable, fertile offspring
reproductive isolation
RNA molecules that, together with proteins, make up ribosomes; the
most abundant type of RNA
ribosomal RNA (rRNA)
Describing a phylogenetic tree that contains a branch point (often, the
one farthest to the left) representing the most recent common ancestor
of all taxa in the tree.
rooted
A form of selection in which individuals with certain inherited
characteristics are more likely than other individuals to obtain mates
sexual selection
A character, shared by members of a particular clade, that originated in
an ancestor that is not a member of that clade
shared ancestral
character
An evolutionary novelty that is unique to a particular clade
shared derived
character
Groups of organisms that share an immediate common ancestor and
hence are each other’s closest relatives
sister taxa
An evolutionary process in which one species splits into two or more
species.
speciation
A population or 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
species
Layered rock that results from the activities of prokaryotes that bind thin
films of sediment together.
stromatolite
The formation of new species in populations that live in the same
geographic area
sympatric speciation
A scientific discipline focused on classifying organisms and determining
their evolutionary relationship
systematics
A named taxonomic unit at any given level of classification.
taxon
A vertebrate clade whose members have limbs with digits – includes
mammals, amphibians, and birds and other reptiles
tetrapod
The diploid cell produced by the union of haploid gametes during
fertilization; a fertilized egg
zygote
concept 3.1
the biological species concept emphasizes reproductive isolation
concept 3.2
speciation may take place with or without geographic separation
concept 3.3
speciation may take place with or without geographic separation
concept 3.4
conditions on early earth made the origin of life possible
concept 3.5
the fossil record documents the history of life
concept 3.6
key events in lifes history include the origins of single celled and multi celled organisms and the colonization of land
concept 3.7
the rise and fall of groups of organisms reflect differences in speciation and extinction rates
concept 3.8
major changes in body form can result from changes in the sequences and regulation of developmental genes
concept 3.9
evolution is not goal orientated
concept 4.1
pylogenies illustrate evolutionary relationships
concept 4.2
phylogenies are inferred from morphological and molecular data
concept 4.3
shared characters are used to construct phyogenic trees
concept 4.4
an organisms evolutionary history is documented in its genome
concept 4.5
new information continues to revise our understanding of the tree of life
Which species concept is currently most popular among most biologists?
A. phylogenetic
What was the species concept most used by Linnaeus?
C. morphological
Two species of frogs belonging to the same genus occasionally mate, but the offspring
fail to develop and hatch. What is the mechanism for keeping the two frog species
separate
A. the postzygotic barrier called hybrid inviability
the biological species concept is inadequate for grouping
C. asexual organisms
The difference between geographic isolation and habitat differentiation is the
The difference between geographic isolation and habitat differentiation is the
Among known plant species, which of these have been the two most commonly
occurring phenomena leading to the origin of new species? 1. allopatric speciation; 2.
sympatric speciation; 3. sexual selection; 4. Polyploidy
D. 2 and 4.
Beetle pollinators of a particular plant are attracted to its flowersʹ bright orange
colour. The beetles not only pollinate the flowers, but they mate while inside of the
flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in this example, and what has driven it?
B. sympatric speciation, habitat differentiation
Which of the following would be a position held by an adherent of the punctuated
equilibrium theory?
A. A new species forms most of its unique features as it comes into existence
and then changes little for the duration of its existence
Speciation
E. can involve changes involving a single gene
Which of the following statements about speciation is correct?
E. Speciation is a basis for understanding macroevolution
What probably accounts for the switch to DNA-based genetic systems during the
evolution of life on Earth?
A. DNA is chemically more stable and replicates with fewer errors (mutations)
than RNA
What is true of the fossil record of mammalian origins?
C. It includes transitional forms with progressively specialized teeth
Which free-living cells were the earliest contributors to the formation of Earth’s
oxidizing atmosphere?
A. cyanobacteria.
What is thought to be the correct sequence of these events, from earliest to most
recent, in the evolution of life on Earth? 1. origin of mitochondria; 2. origin of
multicellular eukaryotes; 3. origin of chloroplasts; 4. origin of cyanobacteria; 5. origin
of fungal-plant symbioses
C. 4, 1, 3, 2, 5.
A major evolutionary episode that corresponds in time most closely with the
formation of Pangaea was the
C. Permian extinctions
The following question is based on the observation that several dozen different
proteins comprise the prokaryotic flagellum and its attachment to the prokaryotic cell,
producing a highly complex structure. If the complex protein assemblage of the
prokaryotic flagellum arose by the same general processes as those of the complex
eyes of molluscs (such as squids and octopi), then
B. ancestral versions of this protein assemblage were either less functional, or
had different functions, than modern prokaryotic flagella
It has been found that certain proteins of the complex motor that drives bacterial
flagella are modified versions of proteins that had previously belonged to plasma
membrane pumps. This is evidence in support of the claim that
D. natural selection can produce new structures by cobbling together parts of
other structures
An explanation for the evolution of insect wings suggests that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding
through the air, and selection later refined them as flight-producing wings. If this hypothesis is correct, insect wings could best be described as
C. exaptations.
The existence of evolutionary trends, such as increasing body sizes among horse
species, is evidence that
D. in particular environments, similar adaptations can be beneficial in more than one species
Fossil evidence indicates that several kinds of flightless dinosaurs possessed feathers.
If some of these feather-bearing dinosaurs incubated clutches of eggs in carefully
constructed nests, this might be evidence supporting the claim that
B. their feathers originally served as insulation, and only later became flight
surfaces
The legless condition that is observed in several groups of extant reptiles is the result of
C. several instances of the legless condition arising independently of each other
The various taxonomic levels (viz, genera, classes, etc.) of the hierarchical
classification system differ from each other on the basis of
C. their inclusiveness
Which of the following pairs are the best examples of homologous structures?
A. bat wing and human hand
If organisms A, B, and C belong to the same class but to different orders and if
organisms D, E, and F belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology?
E. D and F
n angiosperm plants, flower morphology can be very intricate. If a tree, such as a New
Mexico locust, has flowers that share many morphological intricacies with flowers of
the sweet pea vine, then the most likely explanation for these floral similarities is the
same general explanation for the similarities between the
D. cranial bones of humans and those of chimpanzees.
The term that is most appropriately associated with clade is
C. monophyletic
The common ancestors of birds and mammals were very early (stem) reptiles, which
almost certainly possessed 3-chambered hearts (2 atria, 1 ventricle). Birds and
mammals, however, are alike in having 4-chambered hearts (2 atria, 2 ventricles). The
4-chambered hearts of birds and mammals are best described as
C. homoplasies.
The term that is most appropriately associated with clade is
C. homoplasies.
If birds are excluded from the class Reptilia, the term that consequently describes the
class Reptilia is
A. paraphyletic
If the eukaryotic condition arose, independently, several different times during
evolutionary history, and if ancestors of these different lineages are extant and are
classified in the domain Eukarya, then the domain Eukarya would be
B. polyphyletic.
Phylogenetic hypotheses (such as those represented by phylogenetic trees) are
strongest when
C. they are supported by more than one kind of evidence, such as when fossil
evidence corroborates molecular evidence.
Concerning growth in genome size over evolutionary time, which of these does not
belong with the others?
A. orthologous genes
Species that are not closely related and that do not share many anatomical similarities
can still be placed together on the same phylogenetic tree by comparing their
E. homologous genes that are highly conserved
The reason that paralogous genes can diverge from each other within the same gene
pool, whereas orthologous genes diverge only after gene pools are isolated from each
other, is that
D. having an extra copy of a gene permits modifications to the copy without loss
of the original gene product
The human nuclear genome includes hundreds of genes that are orthologs of bacterial
genes, and hundreds of other genes that are orthologs of archaean genes. This finding
can be explained by proposing that
B. the eukaryotic lineage leading to humans involved at least one fusion of an
ancient bacterium with an ancient archaean.
A large proportion of archaeans are ʺextremophilesʺ, so called because they inhabit
extreme environments with high acidity and/or high temperature. Such environments
are thought to have been much more common on the primitive Earth. Thus, modern
extremophiles survive only in places that their ancestors became adapted to long ago.
Which of these is, consequently, a valid statement about modern extremophiles,
assuming that their habitats have remained relatively unchanged?
B. On a phylogenetic tree whose branch lengths are proportional to amount of
genetic change, the branches of the extremophiles should be shorter, relative
to branches of the non-extremophilic archaeans.
