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20 Flashcards

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1
Q

Evidence of ancient life

A

stromatolites: 3.2 BYA

layers of sediment left by cyanobacterial mats

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2
Q

Are stromatolites evidence of life or non-organic origin?

A

2008 study of 2.7 Gy stromatolites: Found shapes similar to bacteria, associated with the kind of nanocrystals in modern bacteria-grown stromatolites.

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3
Q

What was in the microfractures? (originally thought to be carbon)

A

hematite deposits

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4
Q

What happened when energy was added to Earth’s early atmosphere?

A

The basic building blocks of life were created

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5
Q

primordial soup model (list characteristics)

A

– Early oceans full of organic material
– Methane-ammonia atmosphere
– Addition of external energy (heat/UV/lightning)
into these gases end up into monomers
– Most widely accepted model

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6
Q

Urey-Miller Experiment

A

Abiotic production of amino acids, resulting in the production of 13 of 22 amino acids used in living systems

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7
Q

How did life come from outer space?

A

comets

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8
Q

Evidence of comets carrying life + what did these comets carry?

A

intense early bombardment of Earth by rocky and icy bodies

carry organic molecules, amino acids
ex. Murchison meteorite

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9
Q

How did life come from the center of the Earth?

A

hydrothermal waters

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10
Q

Primitive bacteria at surface of Earth

A

chemotrophs – Yellowstone hot spring bacteria

similar bacteria found in very deep wells, mid-ocean ridge black smokers

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11
Q

2 main types of organisms

A

prokaryote, eukaryote

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12
Q

characteristics of prokaryote

A

small, no nucleus, limited organelles, simple ring chromosome with few genes

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13
Q

characteristics of eukaryote

A

large, organelles, nucleus, complex chromosomes with many genes

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14
Q

symbiosis

A

evolution of eukaryotes from prokaryotes

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15
Q

gene flow

A

movement of alleles between pop due to migration

tends to make pop more genetically similar over time (uniform allele freq)

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16
Q

genetic swamping

A

the reduction in a population’s ability to adapt due to gene flow from a maladapted population

local genotypes replaced with hybrids

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17
Q

adaptive introgression

A

alleles move between populations via gene flow, helping local pop adapt to environment w/o needing new mutations

introducing something foreign that leads to better fitness

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18
Q

what can gene flow lead to?

A

new populations, new traits, even new species

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19
Q

speciation

A

the process by which one species splits into two species

this is an example of macroevolution

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20
Q

microevolution

A

changes in allele frequency in a population over time

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21
Q

macroevolution

A

broad patterns of evolutionary change above the species level

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22
Q

How do new species originate from existing species?

A

Over time, populations of a single species connected by gene flow can diverge genetically, giving rise to a new species

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23
Q

species

A

basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity

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24
Q

most common way to define species

A

biological species concept

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25
biological species concept
according to BSC, a species is a group of pop whose members - have potential to interbreed in nature - produce viable, fertile offspring - do NOT produce viable, fertile offspring with members of other such groups
26
how does reproductive isolation occur
it results when biological barriers impede members of two species from interbreeding and producing viable, fertile offspring classified by whether factors act before or after fertilization
27
what do these barriers limit
formation of hybrids and gene flow between the forming species
28
the BSC relies on the disruption of which aspect of pop genetics?
gene flow
29
2 main types of biological barriers
prezygotic barriers, postzygotic barriers
30
prezygotic barrier
blocks fertilization from occuring by: - impeding diff species from attempting to mate - preventing successful completion of mating - hindering fertilization if mating is successful
31
zygote
diploid cell produced by the union of haploid gametes during fertilization; i.e. a fertilized egg
32
types of prezygotic barriers
habitat isolation temporal isolation behavioral isolation mechanical isolation pollinator isolation gametic isolation
33
habitat isolation
2 species that occupy diff habitat within same area may encounter each other rarely
34
temporal isolation
species that breed at diff times of day cannot mix their gametes nocturnal animals and diurnal animals
35
behavioral islation
courtship rituals and other unique behaviors to a species are effective barriers to mating
36
pollinator isolation
species of plant that attract diff types of pollinators have barrier to reprod bee pollinating flower vs hummingbird pollinating flower
37
mechanical isolation
mating attempted, but morphological diff prevent completion
38
gametic isolation
sperm of one species may not be able to fertilize eggs of another sperm L sperm fr
39
postzygotic barriers
prevent hybrid zygotes from developing into viable, fertile adults - reduced hybrid viability - reduced hybrid fertility - hybrid breakdown
40
reduced hybrid viability
genes of diff parent species may interact in ways that impair hybrid's development or survival in environment
41
reduced hybrid fertility
meiosis may fail to produce normal gametes, resulting in sterility mules (donkey + horse) are sterile
42
hybrid breakdown
first gen viable, offspring in next gen are not
43
limitations of BSC
of species to which BSC is applied is limited, cannot be applied to extinct, asexual organisms bc mating cannot observed
44
morphological species concept
distinguishes a species by its structural features, applied to sexual and asexual species and does not require info on the extent of gene flow disadvantage is that it relies on subjective criteria
45
ecological species concept
defines a species by its ecological niche (sum of its interactions with nonliving and living parts of the environment), applies to sexual and asexual species, emphasizes role of disruptive selection
46
2 types of speciation
allopatric speciation, sympatric speciation
47
allopatric speciation
pop are geographically isolated; physical separation due to geographic isolation prevents interbreeding most common form of speciation
48
sympatric speciation
pop not geographically isolated
49
process of allopatric speciation
geographic separation creates 2 populations of same species isolated from each other (no genetic exchange can occur between them) can occur when pop is divided into geographically isolated subpopulations (vicariance) or when individuals colonize a remote area (dispersal)
50
how is reprod isolation affected by geographic distance?
reprod isolation between pops generally increase w geographic distance isolated subdivided regions usually have more species than those w fewer barriers
51
process of sympatric speciation
speciation occurs in pop that live in same geographic area, occurs if gene flow reduced by polyploidy, sexual selection, habitat differentiation
52
polyploidy
presence of extra sets of chromosomes, process can form new species within single gen w/o geographic separation can happen with hybridization (allopolyploidy) and without it (autopolyploidy)
53
sexual selection
certain traits can increase your chances to mate, can result from the exploitation of new habitats or resources
54
how to study rate of speciation?
by observing broad patterns in fossil record speciation can occur rapid or slow
55
punctuated equilibria model
describes a sudden rapid evolution brought on by the pressures (stress) exerted on species species appear to have changed gradually over time
56
hybrids
hybrids result of mating between species with incomplete reprod barriers
57
hybrid zone
region in which members of different species mate and produce hybrid offspring typically located wherever habitats of interbreeding species meet; occurs as isolated patterns scattered across landscape rather than a continuous band
58
possible outcomes in a hybrid zone
reinforcement, fusion, stability, hybrid speciation
59
reinforcement
substantial gene flow between species if hybrids are as fit as their parents, reprod barriers can weaken and the 2 parent species may fuse into single species
60
stability
Extensive gene flow from outside the hybrid zone can overwhelm selection for increased reproductive isolation inside the hybrid zone
61
hybrid speciation
Hybrid in a hybrid zone may become reproductive isolated from both parental types
62
how does environment affect hybrid zones?
changing environmental conditions can result in the relocation of existing hybrid zones, can also drive the production of new hybrid zones
63
fusion
gene flow between 2 species that can form hybrid offspring weakens barriers to reproduction between species process causes gene pools to become increasingly alike and can cause 2 species to fuse into single species
64
uses for phylogenetics
Monitor pathogen evolution, track cancer tumor progression and metastasis, understand protein structure and function, understand evolutionary adaptations across the tree of life
65
what do nodes represent on phylogenetic tree?
common ancestors
66
what do tips represent on phylogenetic tree?
taxa
67
what does the root represent on phylogenetic tree?
the common ancestor to everything included to tree
68
different shapes of phylogenies
triangular tree, circular tree, unrooted tree, rectangular tree
69
sister taxa
when 2 taxa share a most common ancestor
70
clade
all the tips arising from a node
71
monophyletic
group that includes all of a clade
72
paraphyletic
group which includes most, but not all of clade which shares a common ancestor
73
convergent evolution
same morphology appears independently in the tree of life the reason why morphological features are limited for phylogenetic analyses
74
what genes used for phylogenetic analyses when using molecular features?
housekeeping genes, ex. ribosomal RNA seq
75
polytomy + two types
when a node have more than 2 branches soft polytomy, hard polytomy
76
soft polytomy
phylogenies that include polytomys to reflect uncertainty in evolutionary model
77
hard polytomy
when there is true multifurcation in tree of life -- rare but is possible in allopatric scenario
78
branch lengths
number of amino acid substitutions per site
79
homologs
genes with similar seq
80
orthologs
gene pairs separated by speciation
81
paralogs
gene pairs separated by gene duplication
82
duplicate genes can:
subfunctionalize or neofunctionalize
83
subfunctionalize
two paralogs each take on some of the functions of the ancestral gene
84
neofunctionalize
one paralog retains ancestral function, while other can mutate and evolve new functions
85
why are gene family phylogenies discordant with species phylogenies?
genetic material can jump across the tree of life, common in prokaryotes and contributes to evolution of antibiotic resistant bacteria
86
why do insects use effectors?
to manipulate plant development (galls) and defense
87
What are effectors?
small molecules that selectively bind to proteins to regulate biological activity secreted by pathogens/pests into host cells
88
what are galls
abnormal growths on leaves, due to insect feeding, can provide a home for the insect to lay eggs
89
ankyrin repeat proteins
33 amino acid motifs mediates protein-protein interaction predominantly found in eukaryotes with fundamental functions (signal transduction, cell cycle regulation, etc.) defects in ARPs results in a # of human of diseases
90
insects consume what percentage of major crops?
20-40%
91
what does root infestation do?
disrupts water and nutrient uptake, resulting in yield reduction and even vine death
92
vicariance
population is divided into geographically isolated subpopulations A|A --> B|C
93
dispersal
when individuals colonize a remote area A| --> A|A --> A|B

BIO 5C (4 decks)

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