Ecology Exam 4 Flashcards
1
Q
what are the steps of how a species originates from existing species
A
-populations are connected by gene flow
-a barrier to gene flow is established
-this population begins to diverge genetically
-this population is reproductively isolated, forming a new species
2
Q
what is speciation
A
the process by which one species splits into two or more species, is at the focal point of evolutionary theory
3
Q
what is microevolution
A
consists of changes in allele frequency in a population over time
4
Q
what is macroevolution
A
refers to broad patterns of evolutionary change above the species level
5
Q
____ form a bridge between microevolution and macroevolution
A
speciation
6
Q
The biological species concept emphasizes ____ isolation
A
reproductive
7
Q
what is a species
A
is a group of populations whose members can interbreed in nature and produce offspring; they do not breed successfully with members of other such groups
8
Q
____ ____ between populations holds a species together genetically
A
gene flow
9
Q
The biological species concept is based on the ____ to ____, not on physical similarity
A
potential to interbreed
10
Q
what is reproductive isolation
A
is the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring
11
Q
what are hybrids
A
are the offspring that result from mating between different species
12
Q
what are prezygotic barriers
A
-habitat isolation
-temporal isolation
-behavioral isolation
-mechanical isolation
-gametic isolation
13
Q
how do prezygotic barriers block fertilization from occurring
A
-Impeding different species from attempting to mate
-Preventing the successful completion of mating
-Hindering fertilization if mating is successful
14
Q
what is habitat isolation
A
Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers
15
Q
what is temporal isolation
A
Species that breed at different times of the day, different seasons, or different years cannot mix their gametes
16
Q
what is behavioral isolation
A
Courtship rituals and other behaviors unique to a species are effective barriers to mating
17
Q
what is mechanical isolation
A
Morphological differences can prevent successful completion of mating
18
Q
what is gametic isolation
A
Sperm of one species may not be able to fertilize eggs of another species
19
Q
how do postzygotic barriers prevent hybrid zygote from developing into a viable, fertile adult
A
-Reduced hybrid viability
-Reduced hybrid fertility
-Hybrid breakdown
20
Q
what is reduced hybrid viability
A
Genes of the different parent species may interact and impair the hybrid’s development or survival in its environment
21
Q
can hybrids be sterile
A
yes, mules
22
Q
what is hybrid breakdown
A
Some first-generation hybrids are fertile, but when they mate with each other or with either parent species, offspring of the next generation are feeble or sterile
23
Q
The biological species concept cannot be applied to ____ or ____ organisms (including all prokaryotes)
A
fossils or asexual
24
Q
The biological species concept emphasizes the ____ of gene flow
A
absence
25
can gene flow occur between morphologically and ecologically distinct species
yes, grizzly and polar bears
26
how does the morphological species concept define a species
-structural features
-body shape
-other structures
27
does the morphological species concept apply to sexual and asexual species
yes
28
what does the ecological species concept define a species in terms of what
its ecological niche
29
what role does the ecological species concept emphasize
disruptive selection
30
does the ecological species concept apply to both sexual and asexual species
yes
31
what are the two ways that speciation can occur
-allopatric
-sympatric
32
can speciation take place with or without geographic separation
yes
33
what happens in allopatric speciation
gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations
34
what does the definition of a barrier depend on
the ability of a population to disperse
35
Separated populations may evolve independently through ____, ____ ____, and ____ ____
mutation, natural selection, and genetic drift
36
Reproductive isolation may arise as a by-product of ____ divergence
genetic
37
what is a example of evidence of allopatric speciation
fruit flies taken from the same source population and allowed to adapt to different diets over several generations tend to choose mates adapted to the same diet
38
Regions with ____ geographic barriers typically have more species than do regions with _____ barriers
many, fewer
39
when reproductive isolation between populations increases what also increases
the distance between them increases
40
is physical separation alone a biological barrier
no
41
reproductive barriers are ____ to the organisms themselves
intrinsic
42
what occurs in sympatric speciation
speciation occurs in populations that live in the same geographic area
43
Sympatric speciation can occur if gene flow is reduced by factors including
-polyploidy
-sexual selection
-habitat differentitation
44
what is polyploidy
is the presence of extra sets of chromosomes due to accidents during cell division
45
is polyploidy more common in plants or animals
plants
46
how quickly can polyploidy produce new biological species in sympatry
within a single generation
47
what is a autopolyploid
is an individual with more than two chromosome sets derived from a single species
48
The offspring resulting from mating between polyploids and diploids have ____ fertility
reduced
49
what is allopolyploid
is a species with multiple sets of chromosomes derived from different species
50
Allopolyploids can successfully mate with each other, but cannot interbreed with either ____ species
parent
51
____ selection can drive sympatric speciation
sexual
52
what type of selection contributed to speciation in cichlid fish in Lake Victorie
sexual
53
____ speciation can also result from the appearance of new ecological niches
sympatric
54
what is a hybrid zone
a region in which members of different species mate and produce hybrids
55
____ are the result of mating between species with incomplete reproductive barriers
hybrids
56
A hybrid zone can occur in a ____ ____ where adjacent species meet
single band
57
Hybrids often have reduced ____ compared with parent species
fitness
58
The distribution of hybrid zones can be more complex if parent species are found in ____ within the same region
patches
59
what can result in the relocation of existing hybrid zones or the production of novel hybrid zones
change in environmental conditions
60
Breeding between hybrids and parent species can result in the transfer of ____ from one parent species to the other
alleles
61
In a changing environment: the transfer of novel alleles may help parent species do what with changing conditions
cope with changing conditions
62
If hybrids do not become reproductively isolated from their parent species, then three alternate outcomes are possible:
-reinforcement
-fusion
-stability
63
what does reinforcement do
strengthens reproductive barriers
64
when does reinforcement of reproductive barriers occur
when hybrids are less fit than parents
65
what does fusion do
weakens reproductive barriers
66
when does fusion occur
if hybrids are as fit as parents, there can be substantial gene flow between species
67
how does fusion occur
reproductive barriers weaken, fusion occurs and the two species become one. The hybrids are as fit or more fit than the parents, the two species may fuse back into one species
68
what does stability do
continued formation of hybrid individuals
69
what causes stability
Barriers remain the same if hybrids are fit and reproductive. Two species will remain separate but also continue to interact to produce some hybrid individuals
70
how can the rate of speciation be studied
using the fossil record, morphological data, or molecular data
71
what does punctuated equilibria describe
these periods of apparent stasis punctuated by sudden change
72
what are speciation rates
The punctuated pattern in the fossil record and evidence from lab studies suggest that speciation can be rapid
73
how many genes influence the formation of new species
Depending on the species in question, speciation might require change in a single gene or many genes
74
macroevolution is the cumulative effect of what
of many speciation and extinction events
75
The fossil record shows macroevolutionary changes over large time scales, for example:
-the emergence of terrestrial vertebrates
-the impact of mass extinctions
-the origin of key adaptations, such as flight
76
what is abiogenesis
the original evolution of life or living organisms from inorganic or inanimate substances
77
when did earth form
4.6 billion years ago
78
what did Oparin and Haldane hypothesize about the early atmosphere
is was a reducing environment
79
where did the first organic compounds may have formed in reducing conditions
near the openings of volcanoes
80
Some evidence suggests that the early atmosphere was neither ____ or ____
reducing, oxidizing
81
Organic compounds could have been produced in deep-sea ____ ____
hydrothermal vents
82
what was another source of organic molecules
meteorites
83
what is the abiotic synthesis of macromolecules
-RNA monomers have been produced spontaneously from simple molecules
-RNA polymers form spontaneously when a solution of monomers is dripped onto hot sand, clay, or rock
-Such abiotically synthesized polymers could have acted as weak catalysts on early Earth
84
how were vesicles formed
-Adding montmorillonite, a soft mineral clay common on early Earth, greatly increases the rate of vesicle formation, and some can self replicate.
-They can absorb organic molecules attached to montmorillonite particles through a selectively permeable bilayer
85
where did replication and metabolism first appear
protocells
86
where did protocells form from
from fluid-filled vesicles with a membrane-like structure
87
what was the first genetic material
RNA
88
what did RNA provide the template for
the formation of DNA
89
how does DNA differ from RNA
-more chemically stable
-replicated more accurately
90
what species is the fossil record biased towards
-existed for a long time
-were abundant and widespread
-had hard parts, such as shells or skeletons
91
how is the age of older fossils estimated
by using isotopes with long half-lives to date the rock layers above and below the fossil
92
can we find out the actual ages of fossils
no
93
how can the age of a fossil be determined
radiometric dating
94
can fossils contain isotopes
yes, they accumulated in the organisms when they were alive
95
how can the age of some fossils be estimated by measuring what
ratio of the radioactive isotope carbon-14 to the stable isotope carbon-12
96
how far can radiocarbon dating be used to date fossils
75,000 years old
97
do organisms take up isotopes with long half-lives
no
98
The evolution of unique mammalian features can be traced in the ____ ____
fossil record
99
Mammals belong to the group of animals called ____
tetrapods
100
what eons is the geologic record divided into
-hadean
-Archaean
-Proterozoic
-phanerozoic
101
what eon includes the last half billion years
Phanerozoic
102
what era did the Cambrian explosion occur
paleozoic
103
what periods are in the paleozoic era (oldest to youngest)
Cambrian, Permian
104
what periods are in the Mesozoic era (oldest to current)
Triassic, Jurassic, cretaceous
105
what period is in the Cenozoic era
-quaternary
106
what time frame is the holocene epoch
11.7 Ka to today
107
what epoch is in the quaternary period
holocene
108
what eras is the Phanerozoic divided into (oldest to youngest)
Paleozoic, Mesozoic, and Cenozoic
109
Major boundaries between eras correspond to major ____ events in the fossil record
extinction
110
when were dinosaurs abundant
Triassic, Jurassic, Cretaceous
111
what are the oldest known fossils
stromatolites (rocks formed by the accumulation fo sedimentary layers on bacterial mats)
112
what time do stromatolites date back to
3.5 billion years ago
113
when were prokaryotes Earth's sole inhabitants
for more than 1.5 billion years
114
is most atmospheric oxygen of biological origin
yes
115
when did oxygen accumulate gradually in the atmosphere
2.7-2.4 billion years ago
116
what did the oxygen revolution cause
the extinction of many prokaryotic groups
117
the oldest fossils of eukaryotic cells date back to when
1.8 billion years
118
what did eukaryotes originate from
endosymbiosis
119
what is endosymbiosis
when a prokaryotic cell engulfed a small cell that would evolve into a mitochondrion
120
what is an endosymbiont
is a cell that lives within a host cell
121
All eukaryotes have mitochondria or remnants of mitochondria, but not all have ____ (chloroplasts and related organelles)
plastids
122
Mitochondria and plastids likely descended from ____ cells
bacterial
123
A hypothesis for the origin of mitochondria and plastids through serial ____
endosymbiosis
124
what is the evidence supporting an endosymbiotic origin of mitochondria and plastids
-Inner membranes of both organelles are similar to plasma membranes of living bacteria
-DNA structure and cell division are similar to bacteria
-Both organelles transcribe and translate their own DNA
-Ribosomes are more similar to bacterial than to eukaryotic ribosomes
125
what period did dinosaurs evolve and radiate
triassic
126
what period did dinosaurs go extinct
end of the cretaceous period
127
what did the evolution of eukaryotic cells allow for
a greater range of unicellular forms
128
A second wave of diversification occurred when ____ evolved and gave rise to algae, plants, fungi, and animals
multicellularity
129
what are the oldest fossils of multicellular eukaryotes
red algae
130
when did the mesozoic era end
66 Ma
131
when did the creataceous period end
66 Ma
132
when did the permian period end
252 Ma
133
when did the paleozoic era end
252 Ma
134
when did the mesozoic era begin
252 Ma
135
when did the triassic period begin
252 Ma
136
when did the cambrian period begin
541 Ma
137
when did the paleozoic era begin
541 Ma
138
when did the phanerozoic eon begin
541 Ma
139
what are the eras in order from oldest to youngest
paleozoic, mesozoic, cenozoic
140
what are the periods of the paleozoic from oldest to youngest
cambrain, permian
141
what are the periods of the mesozoic era from oldest to youngest
triassic, jurassic, cretaceous
142
what are the eons from oldest to youngest
-hadean, archean, proterozoic, phanerozoic
143
when did the hadean eon begin and end
4.56 Ga to 4.0 Ga
144
when did the archean eon begin and end
4.0 Ga to 2.5 Ga
145
when did the proterozoic eon being and end
2.5 Ga to 541 Ma
146
what are the ediacaran biota
an assemblage of larger and more diverse soft-bodied organisms that lived 635 to 541 mya
147
what was the Cambrian explosion
refers to the sudden appearance of fossils resembling modern animal phyla in the Cambrian period
148
when did the trilobtes appear
during the cambrian explosion
149
what animals appear before the Cambrian explosion
sponges, cnidarians, and mollusks
150
what event provides evidence of predator-prey interactions
Cambrian explosion
151
Molecular and fossil data suggest that the Cambrian explosion had a ____ ____
long fuse
152
Fungi, plants, and animals began to colonize land about ____ million years ago
500
153
what adaptations did plants evolve to survive on land
reproduction and avoiding dehydration
154
____ and ____ are the most widespread and diverse land animals
arthropods, tetrapods
155
what did tetrapods evolve from
lobe-finned fishes
156
when did tetrapods evolve from lobe-finned fishes
365 mya
157
what did the human linage evolve from
tetrapods
158
when did the human lineage evolve from tetrapods
6-7 mya
159
when did the modern human originate
195,000
160
The rise and fall of groups depend on ____ and ____ rates within the group
speciation, extinction
161
how many times have the landmasses of Earth formed a supercontinent
three times
162
what causes continental drift
movements in the mantle cause the plates to move over time
163
when did Pangaea form
350 mya
164
what effects did Pangaea have
-a deepening of ocean basins
-a reduction in shallow-water habitat
-a colder and drier climate inland
165
what effects does continental drift have on living organisms
-Organisms must adapt, move, or risk extinction as the climate changes in response to continents moving toward or away from the equator
-Separation of landmasses can lead to allopatric speciation
166
what is evidence reflects the historic movement of continents
the distribution of fossils and living groups
167
The fossil record also shows that most species that have ever lived are now ____
extinct
168
Extinction can be caused by changes to a species’ ____ or ____ environment
biotic or abiotic
169
At times, the rate of extinction has increased dramatically and caused a ____ ____
mass extinction
170
when did the Permian extinction occur
between the Paleozoic and Mesozoic Eras 252 mya
171
what factors contributed to the Permian extinction event
-extreme volcanism
-global warming and ocean acidification
-anoxic conditions
172
what percentage of the marine animal species went extinct during the Permian extinction
96%
173
what caused the cretaceous mass extinction
-meteorite impacts the earth
-dust clouds block sunlight and disturb global climate
174
Scientists estimate that the current rate of extinction is ____ to ____ times the typical background rate seen in the fossil record
100 to 1,000
175
why are many species declining rapidly
-habitat loss
-introduced species
-overharvesting
176
Climate change may ____ declines in species
hasten
177
Mass extinctions can change the ____ of organisms found in ecological communities
types
178
what is adaptive radiation
is the rapid evolution of diversely adapted species from a common ancestor
179
what can cause adaptive radiation
-mass extinctions
-the evolution of novel characteristics
-the colonization of new regions (islands)
180
when did mammals undergo an adaptive radiation
after the extinction of terrestrial dinosaurs
181
when opened up when the dinosaurs disappeared
ecological niches for mammals
182
what allows organisms to adaptive radiate in a new environment
when they have little competition
183
Major changes in body form can result from changes in the ____ and ____ of developmental genes
sequences and regulation
184
Studying genetic mechanisms of change can provide insight into large-scale ____ ____
evolutionary change
185
Genes that program development control the ____, ____, and ____ ____ of changes in an organism’s form as it develops to adulthood
rate, timing, and spatial pattern
186
what is heterochrony
is an evolutionary change in the rate or timing of developmental events
187
what can heterochrony have an impact on
body shape and sexual development
188
what is an example of heterochrony
the contrasting shapes of human and chimpanzee skulls
189
what occurs in paedomorphosis
the rate of reproductive development accelerates compared with somatic development
190
Substantial evolutionary change can also result from alterations in genes that control the ____ and ____ of body parts
placement and organization
191
what do homeotic genes determine
basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged
192
what information do Hox genes provide
positional information during animal embryonic development
193
what are Hox genes a class of
homeotic genes
194
what happens if Hox genes are expressed in the wrong location
body parts can be produced in the wrong location
195
what do new morphological forms come from
gene duplication events that produce new developmental genes
196
Changes in the ____ of ____ ____ have likely contributed more to changes in the form of organisms than sequence changes
regulation of developmental genes
197
what is phylogeny
a hypothesis of the evolutionary history of a species or group of related species
198
what discipline classifies organisms and determines their evolutionary relationships
systematics
199
what shows evolutionary relationships
phylogenies
200
The two-part scientific name of a species is called a ____
binomial
201
what is the first part of a scientific name
genus
202
what is the second part of a scientific name
specific epithet
203
what are the taxonomic groups
-domain
-kingdom
-phylum
-class
-order
-family
-genus
-species
204
A taxonomic unit at any level of hierarchy is called a ____
taxon
205
The broader taxa (i.e. the number of species) are not always ____ between lineages
comparable
206
The evolutionary history of a group of organisms can be represented in a branching ____ ____
phylogenetic tree
207
what does each branch point on a phylogenetic tree represent
represents the divergence of two evolutionary lineages from a common ancestor
208
what are sister taxa
groups that share an immediate common ancestor that is not shared by any other group
209
A ____ tree includes a branch to represent the most recent common ancestor of all taxa in the tree
rooted
210
A ____ ____ diverges early in the history of a group and originates near the common ancestor of the group
basal taxon
211
what do phylogenetic trees show
patterns of descent
212
do phylogenetic trees show phenotypic similarity
no
213
do phylogenetic trees indicate when species evolve or how much change occurred in a lineage
no
214
To infer phylogenies, systematists gather information about the ____, ____, and ____ of living organisms
morphologies, genes, and biochemistry
215
Phenotypic and genetic similarities due to shared ancestry are called ____
homologies
216
Organisms with similar ____ or ____ ____ are likely to be more closely related than organisms with different structures or sequences
morphologies or DNA sequences
217
When constructing a phylogeny, systematists need to distinguish whether a similarity is the result of ____ or ____
homology or analogy
218
what causes a homology
shared anacestry
219
what causes analogy
convergent evolution
220
what does convergent evolution occur
similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages
221
how can homology be distinguished from analogy
-comparing fossil evidence and degree of complexity
-Comparing genes in two organisms that share nucleotide sequence (bioinformatics)
-The more elements that are similar in two complex structures, the more likely it is that they are homologous
222
what are homoplasies
coincidental similarities
223
Shared ____ are used to construct phylogenetic trees
characters
224
Once ____ ____ have been identified, they can be used to infer a phylogeny
homologous characters
225
what are cladistics
an approach to grouping organisms (classification) by common ancestry
226
what is a clade
is a group of species that includes an ancestral species and all its descendants
227
what is a valid clade
if it is monophyletic
228
what does monophyletic signify consist of
that it consists of the ancestor species and all its descendants
229
what are the invalid groupings of clades
-paraphyletic
-polyphyletic
230
what does a paraphyletic grouping consist of
an ancestral species and some, but not all, of the descendants
231
what does a polyphyletic grouping consist of
distantly related species but does not include their most recent common ancestor
232
how are polyphyletic groups distinguished from paraphyletic groups
by the fact that they do not include the most recent common ancestor
233
what is a shared ancestral character
is a character that originated in an ancestor of the taxon
234
what is a derived character
is an evolutionary novelty unique to a particular clade
235
can a character be both ancestral and derived
yes
236
what is an outgroup
is a species or group of species that is closely related to the ingroup
237
what is an ingroup
the various species being studied
238
did the outgroup or ingroup diverge first
outgroup
239
Systematists compare each ingroup species with the outgroup to differentiate between shared ____ and shared ____ characters
derived, ancestral
240
what does maximum parsimony assume
assumes the most likely tree is one that requires the fewest evolutionary events (appearances of shared derived characters)
241
what does maximum likelihood use
using probability rules about how DNA changes over time to develop a tree that reflects the most likely sequence of evolutionary events
242
how do systematists narrow the possibilities of finding the best tree in a large data set
applying the principles of maximum parsimony and maximum likelihood
243
The best hypothesis for a phylogenetic tree fits the most data: ____, ____, and ____
morphological, molecular, and fossil
244
what features do birds and crocodiles share
four-chambered hearts, song, nest building, and brooding
245
The ____ ____ supports nest building and brooding in dinosaurs
fossil record
246
what did the features shared by birds and crocodiles evolve from
a common ancestor
247
Comparing ____ ____ or other ____ to infer relatedness is a valuable approach for tracing organisms’ evolutionary history
nucleic acids, molecules
248
what is useful for investigating branching points that diverged hundreds of millions of years ago
DNA that codes for rRNA
249
what can be used to explore recent evolutionary events
mtDNA
250
An organism’s evolutionary history is documented in its ____
genome
251
____ _____ increases the number of genes in the genome, providing more opportunities for evolutionary changes
Gene duplication
252
Repeated gene duplications result in ____ ____
gene families
253
Like homologous genes, duplicated genes can be traced to a ____ _____
common ancestor
254
where are orthologous genes found
in a single copy of a gene in the genome
255
are orthologous genes homologous between species
yes
256
when can orthologous genes diverge
after speciation occurs
257
what do paralogous genes result from
gene duplication
258
are paralogous genes found in more than one copy in the genome
yes
259
Paralogous genes can diverge within the species that carries them and often evolve ____ ____
new functions
260
____ genes are widespread and extend across many widely varied species
Orthologous
261
are gene number and the complexity of an organism strongly or not strongly linked
not strongly linked
262
Genes in complex organisms appear to be very versatile, and each ____ can encode multiple ____ that perform many different functions
gene, proteins
263
A molecular clock uses constant rates of evolution in some genes to estimate what
the absolute time of evolutionary change
264
in which genes are nucleotide substitutions are assumed to be proportional to the time since they last shared a common ancestor
orthologous
265
in which genes are nucleotide substitutions are proportional to the time since the genes became duplicated
paralogous
266
what are molecular clocks calibrated against
branches whose dates are known from the fossil record
267
If most of the evolutionary change in genes and proteins has no effect on fitness, then the rate of molecular change should be ____
regular
268
Differences in clock rate for different genes are a function of what
-the importance of the gene
-how critical the specific amino acid is to protein function
269
The molecular clock does not run as smoothly as expected if ____ were ____
mutations, neutral
270
how do irregularities result from natural selection
some DNA changes are favored over others
271
Dating the Origin of HIV
-Phylogenetic analysis shows that HIV is descended from viruses that infect chimpanzees and other primates
--HIV spread to humans more than once
--Comparison of HIV samples shows that the virus evolved in a very clocklike way
--The earliest sample of HIV (fragments) is a 1959 blood sample from Kinshasa, Democratic Republic of the Congo
-Application of a molecular clock to one strain of HIV suggests that the strain spread to humans during the 1930s
-A more advanced molecular clock approach estimated the first spread to humans around 1910
272
what are the three domains
bacteria, Archaea, and Eukarya
273
what did early taxonomists classify all species as
either plants or animals
274
what are the five kingdoms that are recognized
Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia
275
what is polytomy
an internal node of a phylogenetic tree linked to three or more child subtrees
276
which domains are more closely related
eukaryotes and archaea are more closely related to each other than to bacteria
277
what is the tree of life based largely on
rRNA genes
278
what is horizontal gene transfer (HGT)
is the movement of genes from one genome to another
279
how does HGT (horizontal gene transfer) occur
by exchange of: transposable elements, plasmids, viral infection, and possibly fusion of organisms
280
how can differences between gene trees be explained
by the occurrence of horizontal gene transfer
281
____ ____ ____ has played a key role in the evolution of both prokaryotes and eukaryotes
Horizontal gene transfer
282
Eukaryotes can acquire nuclear genes from ____ and ____
bacteria and archaea
