Test 1 Flashcards
(189 cards)
1
Q
Fitness
A
Ability to survive and reproduce (pass on ones genes)
2
Q
What leads to adaptive evolutionary change?
A
Natural selection
3
Q
Selective advantage
A
Individuals that survive and produce fertile offspring
4
Q
Natural selection acts on:
A
Phenotype
5
Q
Polygenic control
A
Many plant and animal characteristics are controlled by more than one gene
6
Q
Three kinds of selection which cause changes in the normal distribution:
A
- Stabilizing
- Directional
- Disruptive
7
Q
Stabilizing selection
A
Selects against phenotypic extremes, favors individuals with average phenotypes (Human birth weights)
8
Q
Directional Selection
A
When an environment changes, phenotypes at one extreme of the normal distribution are favored (Allele favored must already be present in the population)
ex. Peppered moths
9
Q
Disruptive Selection
A
Extreme changes in the environment may favor two or more different phenotypes
(Very rare, selects against the average phenotype)
Results in a divergence of distinct groups of individuals within a population
10
Q
Geographic variation
A
Genetic differences among different populations within the same species, such as a cline
11
Q
Cline
A
Gradual change in a species phenotype and genotype through a series of geographically separate populations as a result of an environmental gradient
(Common among species with continuous ranges over large geographic areas)
12
Q
Population genetics
A
The study of genetic variability within a population and of the evolutionary forces that act on it
13
Q
Allele
A
Alternative forms of a gene located at a specific location on a specific chromosome
14
Q
How is it possible to estimate the amount of observed variation that is genetic?
A
By the number, frequency, and kinds of alleles in a population
15
Q
Population gene pool includes
A
All the alleles for all the loci present
16
Q
Diploid
A
Two alleles at each genetic locus
17
Q
How is evolution of populations described?
A
Genotype, phenotype, and allele frequency
18
Q
Genotype
A
Genetic makeup, or combination of alleles, in an individual
19
Q
Allele frequency
A
Fraction of all chromosomes in the population that carry that allele
20
Q
The sum of all genotype frequencies equals
A
one
21
Q
The Hardy-Weinberg Principle
A
Frequencies of alleles and genotypes in a population do not change from generation to generation unless influenced by outside factors
22
Q
Genetic equilibrium
A
A population with no net change in allele or genotype frequencies over time
23
Q
Evolution is occurring if ____ are changing of time
A
Allele frequencies
24
Q
p^2
A
Frequency of AA
25
Q^2
Frequency of aa
26
2pq
frequency of Aa
27
Genetic equilibrium exists only when five conditions are me
1. Random Mating
2. No net mutations
3. Large population size
4. no migration
5. no natural selection
28
Microevolution
Refers to relatively small generation to generation changes in allele or genotype frequencies within a population
29
Five microevolutionary processes
1. nonrandom mating
2. mutaiton
3. genetic drift
4. gene flow
5. natural selection
30
Inbreeding increases:
Frequency of homozygous genotypes
31
Inbreeding depression
Inbred individuals have lower fitness than those not inbred
32
Assortative mating
Individuals select mates by their phenotypes
33
Positive assortative mating
Selection of mates with the same phenotype
34
Negative assortative mating
Selection of mates with different phenotype
35
Genetic drift
Random evolutionary changes in small breeding populations results in changes in allele frequencies in a population
36
Genetic drift decreases
Genetic variation within a population but increases genetic differences among different populations
37
Bottlenecks
Occasionally a population may rapidly and severely decrease due to disease, exploitation, or sudden environmental change
Genetic drift can occur in a small population of survivors causing many allele frequencies to differ from those proceeding the decline
38
Founder effect
Genetic drift tat results when a few individuals from a large population found a new colony
39
Gene flow counteracts
The effects of natural selection and genetic drift
40
Taxonomy
The science of naming, describing, and classifying organisms
41
Who founded modern taxonomy?
Carl Linnaeus
42
Morphological species concept
The classification of plants and other organisms into separate species based on their visible structural differences such as feathers or number of flower parts
43
Binomial nomenclature
Gives each species a name made up of two words ( in latin):
Genus species
44
Genus
First epithet (capitalized)
45
Species
Second epithet (lowercase)
46
The Biological species concept
A species consists of one or more populations whose members interbreed in nature to produce fertile offspring and do not breed with members of other species
47
When do new species evolve?
When populations become reproductively isolated from one another
48
Who first expressed the biological species concept?
Ernst Mayr
49
Shortcomings of BSC
1. Applies only to sexually reproducing organisms
2. Does not apply to bacteria, or extinct organisms
3. Individuals assigned to different species sometimes do successfully interbreed
50
The phylogenetic species concept
A population is declared a separate species if it has undergone evolution long enough for statistically significant differences in diagnostic traits emerge
(Testable by comparing gene sequences between two groups)
51
Shortcomings of PSC
1. Requires thorough studies of DNA sequencing
| 2. Many subspecies would become separate species
52
Prezygotic Barriers
Reproductive isolating mechanisms that prevent mating or fertilization from taking place
53
Types of prezygotic barriers
```
Temporal isolation
habitat isolation
behavioral isolation
mechanical isolation
gametic isolation
```
54
Temporal isolation
Two groups reproduce at different times of the day, season, or year
55
Habitat Isolation
Two closely related species in the same geographic area live and breed in different habitats in that area
56
Behavioral Isolation
Sexual Isolation
Species-specific courtship behaviors
57
Mechanical Isolation
Structural differences in reproductive organs prevent successful mating between species
58
Gametic Isolation
If mating takes place, molecular and chemical differences between species prevents fertilization
59
Postzygotic Barriers
Fertilization occurs between gametes of two closely related species despite their prezygotic barriers
Generally, the embryo of an interspecific hybrid spontaneously aborts
60
Speciation begins when?
When a population becomes reproductively isolated from other populations and their gene pools diverge
61
Allopatric Speciation
Speciation that occurs when one population becomes geographically isolated from others of the species and evolves by natural selection and/or genetic drift
62
Sympatric
Speciation between two populations in the same geographic range
63
When does sympatric speciation occur?
When reproductive isolating mechanisms evolve at the start of the speciation process
64
How does sympatric speciation occur?
In two ways:
A change in ecology or in ploidy
65
Polyploidy
Having more than two sets of chromosomes
66
Autopolyploid
The chromosome complement consists of more than 2 copies of homologous chromosomes (from the same species)
67
Allopolyploid
The chromosome complement consists of more than 2 copies of chromosomes derived from different species
68
When does allopolyploidy occur?
When two species mate to produce a hybrid species
69
How does autopolyploidy arise?
By the fusion of gametes of the same species
70
How does allopolyploidy arise?
By the fusion of gametes of the different species
71
What does autopolyploidy consist of?
Homologous chromosome sets
72
What does allopolyploidy consist of?
All chromosome sets are not homologous
73
What causes autopolyploidy?
Mainly caused by nondisjunction of chromosomes
74
What causes allopolyploidy?
Mating of different species
75
Allopolyploidy gametes have a _____ # of chromosomes from either parent
Different number of chromosomes
76
Outcomes of allopolyploids
1. New species outcompeted by established species (bcomes extinct)
2. New species may coexist with both parental species
3. New species may outcompete and replace parental species
77
Hybrid Zone
An area of overlap between two recently diverged populations in which interbreeding takes place and hybrid offspring are common
78
Three possibilities within hybrid zones:
1. Reinforcement (Hybrids are less fit than parental species)
2. Fusion (Just as fit)
3. Stability (More fit)
79
Two models of evolution based on observed fossil record
1. Punctuated equilibrium
| 2. Phyletic gradualism
80
Punctuated equilibrium
Long periods of stasis are interrupted by short periods of rapid speciation (perhaps triggered by changes in the environment)
81
Phyletic Gradualism
Evolution proceeds continuously over long periods
82
Macroevolution
Large-scale phenotypic changes in populations at the species level and higher such as new species, genera, families, orders, classes, phyla, kingdoms, and domains
83
Adaptive Radiation
The evolutionary diversification of many related species from one or few ancestral species in a relatively short period
May occur when species are able to exploit numerous new ecological opportunities
84
Adaptive Zones
New or vacant ecological niches that were not exploited by an ancestral organism
(Vacant adaptive zones are more common on islands than continents)
85
Four requirements for chemical evolution
1. Little or no free oxygen
2. A source of energy
3. Availability of chemical building blocks
4. Time
86
Two hypothesis explaining the formation of organic molecules
1. Prebiotic soup hypothesis
| 2. Iron-sulfur world hypothesis
87
Prebiotic soup hypothesis
Proposes that organic precursors formed near earths surface
88
Iron-sulfur world hypothesis
Proposes that organic precursors formed at cracks in the oceans floor
89
Microspheres
A type of protobiont formed by adding water to abiotically formed polypeptides
90
Stromatolites
Composed of many minute layers of microbial biofilms
Another type of fossil evidence of early cells
91
Cyanobacteria were first to obtain...
Hydrogen electrons by splitting water
92
Serial endosymbiosis
Suggests that early eukaryotic cells were assemblages of formerly free-living prokaryotes
93
Endosymbionts may have been ___ not ___
Ingested not digested
94
Earths history is divided into
eons, eras, and epochs based on major geologic, climate and biological events
95
Life originated during the
Archaean eon (4.6-2.6 bya)
96
Paleozoic Era
542-251 mya
```
Cambrian
Ordovician
silurian
devonian
carboniferous
permian
```
97
The Cambrian Period
During cambrian radiation evolution was rapid, with the sudden appearance of many new animal body plants
98
The Devonian Period
Explosive radiation of fishes with jaws (The Age of Fishes)
Amphibians, wingless insects, and all major plant groups but flowering plants also originated during this time
99
Carboniferous Period
Amphibians underwent an adaptive radiation and became the dominant carnivores in terrestrial ecosystems
Reptiles, cockroaches and dragonflies appear
100
Permian extinction (Mass Extinction)
Between the permian and triassic periods (251 mya)
more than 90% of marine species and 70% of vertebrate genera living on land became extinct
101
Dinosaurs went extinct
At the end of the cretaceous period (66 mya)
102
When did Human ancestors appear?
In Africa during the late Miocene and early Pliocene epochs
103
When did Genus Homo appear?
Approximately 2.5 mya
A mass extinction of large mammals at the end of the Pleistocene coincided with the appearance of human hunters
104
Paleoanthropology
The study of human evolution
| Paleo=ancient; Anthropos=human
105
The first primates descended from what?
Small, shrewlike placental mammals that lived in trees and ate insects
106
When did the first primates appear?
By the early Eocene
107
Large brain is associated with
Increased sensory input, intelligence, and socialization
108
Arboreal adaptation
Long, Slender limbs that rotate freely at the hips and shoulders, stereoscopic vision
109
Hominoids
A group composed of apes and hominins
110
Five genera of hominoids in existence today
```
Gibbons
Orangutans
gorillas
chimpanzees
humans
```
111
Homo erectus probably evolved from
Homo ergaster
112
The church insists on
the special creation of mans soul
113
The Catholic faith obliges us to hold that
Sould are immediately created by God
114
The church allows for the possibility that man's body
Developed from previous biological forms
115
Biodiversity
The variety of living organisms and the ecosystems in which they belong
116
Systematics
The scientific study of the diversity of organisms and their evolutionary relationships
117
Classification
Arranging organisms into groups based on similarities that reflect evolutionary relationships among lineages
118
Taxon
A formal grouping of organisms at any given level
119
Taxonomic Levels
```
Species
Genus
Family
Order
Class
Phylum
Kingdom
Domain
```
120
The Three Domains
Archaea
Bacteria
Eukarya
121
Cladogram
A type of phylogenetic tree in which each branch represents a clade
122
Clade
A group of organisms with a common ancestor
123
Node
Branching points
Represents the divergence of two or more new groups from a common ancestor
124
Root
Represents the most recent common ancestor of all the clades depicted in the tree
125
Phylogeny
The evolutionary history of a group of organisms from a common ancestor
126
Homology
The existence of shared ancestry between a pair of structures or genes in different taxa
127
Reversal
A trait reverts to its ancestral state
128
Homoplasy
The development of similar looking structures by the result of adapting to similar environments through convergent evolution
129
Shared Ancestral Characters
Features that were present in an ancestral species and remain present in all groups descended from that ancestor
130
Shared Derived Characters
Novel traits that evolve when two populations separate and begin to evolve independently
Characters that originate in a recent common ancestor and are present in its descendants
131
Molecular Systematics
Focuses on molecular structure to clarify evolutionary relationships
132
Macromolecules that are functionally similar in two different types of organisms are considered homologous if...
Their subunit sequence is similar
133
___ Have been extensively used to determine evolutionary relationships among bacteria
rRNA
134
rRNA analysis has suggested ___ are more closely related to ___ than to ___
Fungi are more closely related to animals that to plants
135
Cladograms show three types of taxonomic relationships
1. Monophyletic groups
2. Paraphyletic groups
3. Polyphyletic groups
136
Monophyletic group
Includes an ancestral species and all its descendants
Defined by shared derived characters
Sister taxa share the most recent common ancestor on a cladogram
137
Paraphyletic Group
Contains a common ancestor and some, but not all, of its descendants
Shares ancestral characters
138
Polyphyletic Group
Consists of several evolutionary lines that do not share the same recent common ancestor
Unnatural grouping that misrepresent evolutionary relationships
139
Out-group Analysis
Used to estimate which attributes are shared derived characters in a given group of organisms
140
Outgroup
A taxon considered to have branched off earlier than the taxa under investigation, the ingroups
141
An ideal out-group is the in-groups
Sister taxon
142
Valid monophyletic group
All members share at least one derived character
143
Each branch reflects the addition of...
One or more shared derived characters
144
Principle of Parsimony
Use the simplest explanation to interpret the data when choosing between multiple, competing cladograms
145
Prokaryotic domains
Archaea and Bacteria
146
Cocci (coccus)
Spherical
147
Cocci description
Occur singly, in groups of twos, in long chains, or clumps
148
Bacilli (Bacillus)
Rod-shaped
149
Bacilli description
Occur as single rods or long chains of rods
150
Spirochete or spirillum
Spirals
Flexible or rigid
151
Spirochete description
A comma-shaped spirillum is a vibrio
152
Cell wall
Around the plasma membrane supports bacterium and keeps the cell from bursting under hypotonic conditions
153
Peptidoglycan
A complex polymer consisting of two amino sugars linked with short polypeptides, to form a single macromolecule that surrounds the entire plasma membrane
154
Peptidoglycan is absent in the ___ cell wall
Peptidoglycan is absent in the archaean cell wall
155
Structurally the wall is necessary for:
1. Maintaining shape
2. Countering the effects of osmotic pressure
3. Providing attachment sites for bacteriophages
4. Providing a rigid platform for surface appendages
156
Gram-Positive
Absorb and retain crystal violet stain
Has a thick peptidoglycan layer
157
Gram-negative
Do not retain the stain
Have an outer membrane and a thin peptidoglycan layer
Lipid portion contains LPS
158
Bacteria also use ___ to attach to surfaces such as rocks, plant roots, or human teeth (dental plaque)
Capsules
159
Bacteria use ___ and ___ to attach to cell surfaces or to each other
Fimbriae and pili
160
Fimbriae
Are hundreds of hairlike appendages made of protein
161
Pili
Appendages that are longer (and fewer) than fimbriae
162
Sex Pili
Help transmit DNA between bacteria
163
Endospores
Dormant, extremely durable cells
164
____ Do not form endospores
Archaea
165
Three parts of a bacterial flagellum
1. basal body
2. a hook
3. a single filament
166
Binary fission
One cell divides into two similar cells in which circular DNA replicates, then an ingrowth of plasma membrane and the cell wall forms a transverse wall
167
Budding
A cell develops a bulge (bud) that enlarges, matures, and eventually separates from the mother cell
168
Fragmentation
Walls develop within the cell, which then separates into several new cells
169
Vertical gene transfer
Transfers genetic material from parent to offspring
170
Horizontal gene transfer
Transfers genetic material to another organism that is not its offspring
171
Three different mechanisms for gene transfer
1. Tranformation
2. Transduction
3. Conjugation
172
___ and ___ are important sources of genetic variation for diversification and adaptation
Horizontal gene transfers and genetic recombination
173
Autotrophs
Use inorganic compounds to manufacture organic molecules
174
Heterotrophs
Obtain carbon atoms from organic compounds made by other organisms
175
Chemotrophs
Obtain energy from chemical compounds
176
Phototrophs
Captures energy from light
177
Nitrification
Conversion of ammonia to nitrite and nitrite to nitrate (a form that can be used by plants and fungi)
178
Archaea have no ___ in cell walls or ____
Peptidoglycan in cell walls or simple RNA polymerase
179
Ester Linkages
Occur in PM of eukaryotes and bacteria
180
Ether linkage
Occur in PM archaea
181
Archaea inhabit ___ Environments
Harsh Environments
182
Two major phyla of Domain Archaea
Crenarchaeota and Euryarchaeota
183
Crenarchaeota
Consist mainly of extreme thermophiles, which require very high or very low temperature for growth
184
Euryachaeota
Methanogens, extreme halophiles and extreme thermophiles
185
Methanogens
inhabit oxygen-free environments
186
Mutualism
Both partners benefit
187
Commensalism
One partner benefits and the other is neither harmed nor helped
188
Parasitism
One partner lives on or in the other
the parasite benefits and the host is harmed
189
Biofilms
Communities of micro-organisms consisting of many species of bacteria, and may include other organisms such as archaea, fungi, and protozoa
