Evolution Flashcards
1
Q
Parapatric speciation
A
Occurs when a smaller population is isolated
2
Q
Sympatric Speciation
A
When a species evolves from a single ancestry whilst inhabiting the same geographical region
3
Q
Allopatric speciation
A
when a biological population becomes separated and isolated from each other, causing them to evolve separately into different species
4
Q
Molecular clock hypothesis
A
DNA and protein sequences evolve at a rate that is relatively constant over time + among different organisms
5
Q
Genetic drift
A
random changes in allele frequencies caused by sampling error
6
Q
Convergent evolution
A
Distantly related species show similar adaptations due to similar selection pressures
7
Q
Succulent
A
fleshy stems store water, small leaves reduce water loss, spines deter herbivores
8
Q
Cacti vs euphorbs
A
Convergent adaptations to life in arid conditions - separated due human intervention
9
Q
THe molcular clock
A
Pairs of species compared for same protein - coding differences highly correlated with divergence derived from fossil data. Genetic differences appear at constant rate
10
Q
neutral theory
A
genetic changes arent due to natural selection, but evolve randomly, are neutral
11
Q
synonymous mutation
A
change in codon doesnt result in chnage to resulting amino acid
12
Q
Microevolution
A
Changes in gene pool of an organism over time
13
Q
Gene pool
A
all alleles of all genes of all individuals in a population, representing total genetic variation
14
Q
Macroevolution
A
large-scale evolution that occurs at the level of species and above
15
Q
What is required for life?
A
Cool temperatures
Gravity
Water
16
Q
How do cool temperatures promote life?
A
Allows molecules to keep shape
17
Q
How does water promote life?
A
- Solvent for molecules to interact
- Protection from radiation
18
Q
Protosomes
A
Organisms whose mouth forms first
19
Q
Deuterosomes
A
Organisms whose mouth forms second
20
Q
protozoan
A
first or primitive life
21
Q
Metazoan
A
multicellular animals
22
Q
Diploblastic
A
containing two tissue layers
23
Q
Triploblastic
A
containing three tissue layers
24
Q
Ectoderm
A
tissue (germ layer) in the outside - gives rise to skin and nervous system
25
Mesoderm
middle germ layer - gives rise to notochord, muscle, kidney, blood
26
endoderm
inside germ layer - gives rise to internal organs
27
Chordate
Animals with notochords
28
Notochord
'chord in back' first tissue to differentiate in chordates
29
Urochordate
animals with notochords in their tails
30
cephalochordate
animals with notochords extending into their heads
31
Echinoderm
prickly skin- groups of animals which include sea urchins
32
Descriptive biology
experiments aiming to define normal embryonic development, w/ minimal disruption of the process. Lead to understanding what happens during development, but not how, no mechanistic insight into how cells achieve their normal fate
33
Experimental biology
Experiments which aim to define how embryonic development occurs.
34
Morphogenesis
Process by which form is generated. Involves coordinated cell movements
35
Gastrulation
Morphogenetic process by which endoderm, mesoderm and ectoderm layers reach final positions in embryos
36
Neurulation
Morphogenetic process by which NS begins to forms, especially formation of the neural tube
37
Blastomere
cell in early embryo
38
Fate map
Assessment of fate of cell or group of cells based on lineage labelling. Part of descriptive embryology, doesnt require disturbing development.
39
specification map
Assessment of what a cell or groups of cells will form if removed from embryonic environment. Experimental embryology
40
Determined
Cell/tissue is determined if it will still develop according to its fate. even when transplanted elsewhere in embryo.
41
Organizer
Dorsal mesoderm at gastrula stage, which induces overlying ectoderm to become neural and induces neighbouring mesoderm to become somitic
42
Nieuwkoop centre
region of early dorsal vegetal pole in blastula stage whihc induces the organiser
43
Arabidopsis
Thale cress
44
Dictyostelium
Slime mould
45
Hydra
Cnidarian
46
Planarians
Flatworms
47
Caenorhabditis
Nematode worm
48
Drosophila
Fruit fly
49
Parhyale
Amphipod crustacean
50
Strongylocentrotus
Sea urchin
51
Ciona
tunicate or sea squirt
52
Brachiostoma
amphioxus
53
Danio
zebrafish
54
Xenopus
clawed frog
55
gallus
chick
56
Mus
mouse
57
Advantages of parhyale hawaiensis
- short generation time
- genetics
- sequenced genome
- high regenerative capacity
- transgenesis
- transparent - imaging
58
-zoa
life
59
blast-
bud (embryonic)
60
meta-
after
61
noto-
back
62
-uro
tail
63
cephalo
head
64
echino
spiny/ prickly
65
Transplantation experiments aim
assess cells and tissues and whether they can alter the fate of their neighbors.
Experimental embryology
66
Enforced expression or mutation of genes
Wrong place/time/level.
FInd out what happens.
Experimental embryology
67
Mosaic development
Stage where cell fates are determined, able to become anything
68
Regenerative development
stage where cell fates have been determined, but are reliant on neighbouring cells for signal
69
Competence
Rage of cell fates available to cells/tissues , can be achieved depending on conditions.
70
Example of cells which are competent to give rise to cell types it would not normally be specified or fated to form
Xenopus
Animal cap cells from blastula stage frog embryos - already fated to give rise to ectodermal tissue, are competent to form any cell in the embryo given the right signals
71
Induction
Process by which a cell or tissue emits signals changing the fate of their neighbouring cells
72
Example of induction in development
Induction of neural ectoderm by dorsal mesoderm at the gastrula stage (organiser experiment)
73
Organiser experiment
Induction of neural ectoderm by dorsal mesoderm at gastrula stage
74
Homeotic mutation
Mutation leading to transformation of one body structure into another, forms correctly but in wrong place
75
Hox gene
family of clustered genes in genome which encode related transcription factors characterised by homeodomain
76
Homeodomain
DNA binding domain
77
Evidence that hox genes give positional identity along anterior - posterior axis
1) expression pattern
2) Comparative embryology
3) Gene knockout experiments
78
How do gene knockout experiments give evidence that hox genes give positional identity along A-P axis
remove function of genes lose expression patterning. shows cells are involved in assigning AP patterning
79
Tandem gene duplication
Unequal cross over due to chromosome mis pairing at meiosis - possibly caused by repeated DNA sequences
Can be segmental or whole duplications
80
Segmental duplication
Giant tandem duplication, affecting whole chunk of chromosome
81
Whole duplication events of genome
Can occur by:
Allotetraploidy-hybridization
Autotetraploidy
82
Allotetraploidy
Hybridization between 2 separate species, formed by meiosis
83
Autotetraploidy
duplication of genome through improper meiosis
84
Homologous genes
2 genes you can see share a common answer: extends to paralogous and orthologous genes
85
Paralogous genes
2 genes sharing a common ancestor within a single genome/organism
86
Example of paralogous genes
Fetal haemoglobin + adult haemoglobin
87
Orthologous genes
2 genes share common ancestor, across species
88
Example of orthologous genes
human and frog insulin gene
89
Gene redundancy
When no phenotype difference is observed when a gene is mutated due to another gene replacing function of mutated gene, essentially masking it.
90
Paralogous genes in gene redundancy
Can mask effects of mutated gene. May receive novel functions - partial redundancy
91
Somite
Segmented blocks in our bodies which give rise to vertebrae, body muscles and dermis in our body axis.
92
Vertebrae
Morphological structure which can be used to assess AP positioning in the body
93
HOw many rounds of tandem duplication has there been in mammals and vertebrates
2
94
Potency
Range of cell fates available to cell or group of cells
95
Founder effect
loss of genetic variation that occurs when a new population forms by a very small number of individuals from a larger population
96
Overdominance
condition wherein a heterozygote produces a phenotype better adapted than the homozygote
97
Analogous genes
Structures with same function but different ancestors
98
Directional selection
Occurs when conditions favour individuals exhibiting on extreme on a phenotypic range, shifting population frequency curve one way or the other
99
Disruptive seletion
Occurs when conditions favour individuals at both extremes of a phenotypic range over individuals with intermediate phenotype.
100
Stabilizing selection
acts against both phenotypes and favours intermediate variants
101
Transitional form
Individuals showing intermediate states between an ancestral form and that of its descendants
102
Postzygotic isolation
reproductive isolation due to decreased fitness and inability to mate
103
Inclusive fitness
Individuals genetic success is derived from cooperation and altruistic behaviour
104
Hamilton's law
r x B > C
B - benefit in number of offspring equivalents gained by recipient of altruism
C - cost suffered
r - genetic relatedness of altruist to beneficiary - possibility gene is shared
105
In plants, the stage of sexual life cycle where cells are haploid is
gametophyte
106
cytosine methylation is associated with
genomic imprinting
107
Where is the SRY gene expressed
in the indifferent gonads of male embryos
108
Evolution occurs under which conditions
heritable traits which vary between individuals and which lead to differential fitness
109
Haplotype
Combination of closely linked SNPs or alleles on single chromosome
110
john gurdon experiment
nuclei from differentiated cells from adult or tadpole can be reprogrammed
111
Incomplete dominance
when dominant allele doesnt completely mask the effects of the recessive gene
