exam 1 Flashcards
1
Q
what is a organism
A
- made up of membrane bound cells
- can reprodue
- process heriditary information encoded in genes as well as information from the environment
- acquire and use energy to stay alive
2
Q
populations of organisms are…
A
constantly evolving
3
Q
species
A
evolutionary independant population or group of populations
4
Q
how are species different from other species?
A
appearance, behavior, etc.
5
Q
population
A
group of individuals of same species living in the same geographic area at the same time, can breed amongst themselves
6
Q
evolution is…
A
the change in characteristics of population overtime
7
Q
species and populations in evolution
A
- species are related to one another and can change overtime
- populations evolve
- changes in populations may lead to new species
* populations evolve NOT individuals
8
Q
genotype
A
genetic information that determines physical traits of individual
9
Q
phenotype
A
physical traits of individual determined by genetic information
10
Q
gene
A
sequence of nucleotides forming part of chromosome (what trait is)
11
Q
allele
A
a variant form of a given gene (W or w) (what type of trait)
12
Q
frequency of alleles
A
the proportion of individuals in a population with a particular allele
13
Q
misconceptions about evolution
A
- evolution is not goal oriented
- it does not perfect organisms
- indivudals do not evolve just populations
14
Q
4 Models of Diversity of Life
A
- Plato: typological thinking
- Aristotle: typological thinking + scale of nature
- Lamarck: scale of nature+ change through time
- Darwin: change through time + common ancestry
15
Q
Inheritance of Acquired Characters
A
- as individuals develop, phenotypes change in response to environmental changes
- phenotypic changes are passed onto offspring
- not examples: nose jobs, body building
- example:giraffes necks stretching over time
16
Q
Natural Selection
A
- individuals with certian heritable traits tend to produce more offspring than those wihtout those traits
- only evolutionary process that produces adaptation
17
Q
Natural selection leads to…
A
change in gentic makeup of population + major mechanism of evolution
18
Q
Darwin and Wallace both understood about evolution that…
A
- species are NOT static
- evolution doesn’t follow a linear, progressive path
- NS is based on variations among indivuals in populations
- individuals in populations with certian traits produce more offspring than other
19
Q
Darwins 4 Postulates
A
- there is variation of traits among individuals in a population
- some of the trait differences are heritable
- more individuals are produced than can survive
- survival and reproduction are non-random and depend of traits
20
Q
Evidence of Evolution
A
- change through time
- species related by common ancestry
21
Q
Evidence 1: Geological Time Scale
A
researches can now assign absolute ages to the geological time scale
22
Q
Evidence 2: Extinction
A
- extinction changes the species present over time
- fossils provide evidence of extinct species
23
Q
Evidence 3: Transitional Features
A
- link older and younger species
- Law of Succession
- traits in fossil species that intermediate betweeen ancestral + dervived species
24
Q
Evidence 4: Vestigal Traits
A
- a reduced or incompletely developed structure in an organism that has no function
- ex. ostriches have wings but can’t fly
25
Evidence 5: Species Changing Today
ex. drug resistance bacteria
26
Evidence 6: Similar species in same area
ex. hawaiian honeycreepers evolved from a single ancestor, adaptive radiation
27
Evidence 7: Homology
similarity that exists in species descended from common ancestor
28
Genetic Homology
similarity in DNA, RNA, or amino acid nucleotide sequences
29
Developmental Homology
similarity in developmental structures or processes among species
30
Structural Homology
similarity in adult morphology
31
Evidence 8: formation of new species
can observe the formation of new species today
32
**Non-random** evolutionary processes
natural, artificial, and sexual **selection**
33
Random evolutionary processes
Mutation, genetic drift and flow
34
Directional Selection
* favors 1 extreme phenotype, causing average phenotype in population to change in 1 direction
* genetic variation is reduced
* orange
35
Stabilizing Selection
* favors phenotypes near the middle of range of phenotypic variation-mainting average phenotype
* genetic variation is reduced
* red
36
Disruptive selection
* favors extreme phenotype at both ends of the range
* gentic variation is increased
* blue
37
balancing selection
* no single phenotype is favored in all populations of a species at all times
* genetic variation is maintained
* green
38
intersexual selection
females/males choose certain males/females to mate with
39
intrasexual selection
males compete against other males to secure a mate
40
artificial selection
non-random reproductive success and mate choice determined by human preference ex. dog breeding
41
genetic drift
* change in allele frequencies in population due to chance
* stronger effects often found in smaller populations
* random
* overtime can lead to loss of alleles=decreased genetic variation
42
Founder Effect and bottleneck cause...
smaller populations
43
Founder event
occurs when group of individuals establish new population in new area
44
founder effect
allele frequencies likely differ from source population if new population is small enough
45
population bottleneck
* sudden decrease in popualtion size in large populations
* leads to genetic bottleneck: sudden reduction in # of alleles in population
46
inbreeding
non-random mating which does not directly cause evolution
47
inbreeding does...
* speed up rate of evolutionary change
* increases probability of getting deleterious recessive alleles
* natural selection eliminates recessive deleterious alleles
48
self fertilization
* most extreme form of inbreeding
* many flowering plants contain both m/f organs and self pollinate
49
gene flow
movement of alleles across populations
50
what does gene flow do
* homogenizes allele frequencies among populations
* can increase genetic diversity by creating new types of alleles
51
mutation
change in the sequences of organisms DNA - ultimate cause of all genetic variation in populations
52
mutations are...
* rare + random
* can occur by point mutations, chromosome-level mutations or lateral gene transfer
* mutations create new alleles not just new combinations
53
Modern Synthesis
* application of Mendelian genetics to Darwinian evolution
* era in 1900s where evolutionary biologists, mathemathics, and genetics collaborated to quantify evolution
54
population genetics
study of processes that change allele and genotype frequencies in populations
55
Hardy-Weinberg Hypothesis
* Wanted to know what happened in an entire
population when all individuals—and thus all possible
genotypes—bred
* Analyzed frequencies of alleles when individual in
population mate and produce offspring
* Gene pool concept
56
Hardy-Weinberg Principle
Serves as mathematical null hypothesis for study of evolutionary processes
57
Speciation
* splitting event that creates two or more distinct species from an ancestral species
* can be rapid or gradual
58
Biologists can identify species through
* biological
* morphological
* phylogenetic
59
Prezygotic isoaltion
isolates before creation of zygote (fertilized egg)
60
postzygotic isolation
isolates after the creation of the zygote
61
morphospecies concept
species are the smallest groups that are consistently and persistently distinct, and have distinguishable traits
62
phylogenetic species
smallest monophyletic group on a phylogenetic tree
63
phylogeny
the branching evolutionary history of a group of organisms is
64
phylogenetic tree
simplified version of phylogeny
65
monophyletic group
any group that forms an evolutionary unit
66
evolutionary tree
compare traits of species that are alive to traits of species that are extinct
* compare DNA of species
* build tree based of shared traits (synapomorphies)
67
evolutionary tree shows...
evolutionary and genetic relationships, time from evolutionary divergence
68
complications of tree
* traits may be similar due to independant evolution (homoplasy) not common ancestry (homology)
* reversal in character state may occur, creating apperance that no change occured
* species can be in 2 different monophyletic groups
69
intact fossil
* Forms when decomposition does not occur and the organic remains are preserved intact.
* ex. Pollen
70
convergent evolution is...
common cause of homoplasy
71
Compression fossil
* Forms when sediments accumulate on top of the organism and become cemented into rocks such as mudstone or shale. The sediments’ weight compresses the organic material below into a thin, carbonaceous film.
* ex. Leaf
72
cast fossil
* Forms when a buried organism decomposes, leaving an empty cavity in the sediments that fills with dissolved minerals and hardens into an accurate cast of the remains.
* ex. Ammonite
73
Permineralized fossil
* Forms when organisms decompose extremely slowly. Dissolved minerals gradually infiltrate the interior of cells and harden into stone
* ex. pertrified wood & bones
74
trace fossil
Forms when sedimentation and mineralization
preserve indirect evidence of an organism in the
environment, including footprints, tracks, burrows,
feeding marks, and feces.
75
Fossil record limitations
* Habitat bias
* Taxonomic and tissue bias
* Temporal bias
* Abundance bias
76
Why polyploidy is common in plants?
Polyploids
* Can tolerate higher levels of self-fertilization: They are not as affected by inbreeding depression as are diploids
Genes on duplicated chromosomes can
diverge independently
* This increases genetic variation in the population
77
Reintroduction
* Populations fusing over time is the simplest outcome of two populations coming into contact: Gene flow erases any distinctions between them
78
Hybrid zone
Geographic area where interbreeding between two populations occurs and hybrid offspring are common
79
life's timeline
* earth started to form ~ 4.6 bya
* life began ~ 3.5 bya
* Precambrian ~4.5 bya- 541mya
* Phanerozoic Era ~ 541mya to present
80
what triggered cambrian explosion
* higher oxygen levels
* rise in algae
* evolution of predation
* new niches beget more new niches
* new genes, new bodies
81
2 general triggers of adaptive radiation
1. favorable new conditons in environment
2. evolution of key morphological, physiological, or behavior traits
82
mass extinction
* rapid exitinction of a large # of diverse species around the world
* opposite of adaptive radiation
* caused by catastrophic events
83
cell type
* Early embryonic cells have the potential to become
almost any cell type
* As cells grow, they are set on a path of differentiation
* Embryonic animal cells commit to an adult state
84
Cell differentiation and specialization
* Signals direct cells to a developmental path
* Two mechanisms for specifying cell fate:
1. Cytoplasmic determinants—Regulatory
molecules that are unequally distributed to
daughter cells
2. Induction—One daughter cell receives a signal
that the other does not
85
Evidence for cell differentiation
* All cells in a plant are genetically equivalent
* Some branch cells can de-differentiate and form root cells
* Entire plants can be grown from a single adult cell
* Clones
86
Cell death is normal
* Highly regulated
* Apoptosis – most common programmed cell death
* Cells that form webbing between toes die
* About half of neurons die as nervous system is wired
* Harmful immune cells are eliminated
87
Fate of a cell depends on its
position along the three body
axes:
1. Anterior to posterior (head to tail)
2. Dorsal to ventral (back to belly)
3. Left to right
88
A gradient and differentiation
* Pattern formation
* Cells receive information based on a gradient- morphogens
* They then differentiate along that gradient
* If this gradient is disrupted, development does not go as intended
89
Gene regulatory cascades
* Genetic regulatory cascades supply progressively detailed information about:
* Where cells are located
* What they are to become
* A genetic regulatory cascade is a set of linked regulatory genes
90
Tool-kit genes
* Mutations allow tool-kit
genes to be used in new
ways in different species
* But there are
developmental
constraints
91
hox genes
* Determine important structures during development
* Hox proteins determine the 'position’ of structures ensuring that the correct structures develop in the correct places in the body.
92
structures
* Cells, tissues, organs
* Traits that help an organism survive in their environment might be under very strong selection
93
constraints
* Genetic: Genes for important features cannot be lost or changed
* Physical: Body size (volume and size)
* Chemical: Moving nutrients among tissues (systems)
