Evolution CHAP 5 Flashcards
1
Q
What is the definition of Evolution?
A
The cumulative change in the heritable characteristics of a population
2
Q
Evolution: The Characteristics are encoded by ___ and transferred between generations as ______
A
1) Genes 2) Alleles
3
Q
_____ is a change in the allele frequency of a populations gene pool over successive generations
A
Evolution
4
Q
Evolutionary changes affect variation and diversification within a population via 6 main mechanisms.
Which are?
A
RANDOM PROCESSES Mutation Sexual Reproduction gene flow genetic drift
SELECTIVE PROCESSES
natural selection
Artifical selection
5
Q
Mutation
A
A change in the DNA base sequence
6
Q
Sexual Reproduction
A
New gene combination
7
Q
Gene Flow
A
Change due to genetic migration
8
Q
Genetic Drift
A
Change due to a chance event
9
Q
Natural Selection
A
Environment drives change
10
Q
Artificial Selection
A
Change is human-induced
11
Q
What are the Mechanisms of variation?
A
Mutation
Sexual reproduction
Gene flow (Species moving)
12
Q
What are the Mechanisms of change?
A
Genetic drift (Chance event) Natural selection (selection Pressures)
13
Q
What is speciation?
How does it happen?
A
Is the formation of a new species due to the divergence of isolated populations
14
Q
The level of _____ between isolated populations will gradually increase the longer the populations are separated.
A
Divergence
15
Q
______ occurs when both ______ diverge to the extent that they can no longer interbreed and produce offspring
A
1) Speciation
2) Populations
16
Q
When can something provide evidence for evolution?
A
When it demonstrates change over time
e.g: Current forms differ from ancestral forms
17
Q
What Provides evidence for Evolution?
A
Fossils Selective breeding Comparative Anatomy Biogeography Comparative Embryology Molecular Evidence
18
Q
What are fossils and what do they provide?
A
- Preserved remains of past life
- Allow comparisons with ancestral organisms
19
Q
What is selective breeding?
A
Human directed breeding patterns promote rapid diversification (i.e. change over time)
20
Q
What is Comparative Anatomy and what does it suggest
A
- Distinct species share a common body plan
- Suggests divergence from a common ancestry
21
Q
What is biogeography?
What does it indicate?
What explains the exceptions to it?
A
- Closely related species are closely located
- Indicates divergence from a common ancestor
- Exceptions explained by continental drift
22
Q
What is Comparative Embryology?
What does it suggest?
A
- Species share similar embryonic development
- Suggestive of a common ancestry
23
Q
Explain Molecular evidence regarding Evolution
A
- Closely related species share a greater degree of similarity in DNA and protein sequences.
24
Q
Define fossil
Than define Fossil record and what it is for
A
Fossil - the preserved remains or trace of an organism from the remote past.
Fossil record - Is the totality of all fossils it shows changes that have occurred in organisms (evolution)
25
Describe what the
LAW OF FOSSIL SUCCESSION
is
Certain organisms appear in the fossil record in a consistant order - indicating an evolutionary sequence of development
26
What comes before what according to the law of fossil succession
- Prokaryotes appear before eukaryotes
- Ferns appear before flowing plants
- Invertebrates appear before vertebrates
27
What are TRANSITIONAL FOSSILS
They represent intermediary forms within the evolution of a genus
(the ARCHAEOPTERYX links the evolution of birds (wings/feathers) to dinosaurs (jaws/claws)
28
What involves the mating of animals with desired characteristics? and what is it an example of?
Selective breeding
| a form of artificial selection
29
As human intervention drives selection, changes will occur over______
fewer generations
30
Give 3 examples of selective breeding
- Draft horses (power) VS racing horses (speed)
- Large variation in types of dog breeds
- Cows selected for muscle mass (Belgian Blue)
31
What are HOMOLOGOUS STRUCTURES
Anatomical features that share a common underlying structure despite having distinct functions.
32
A rapid diversification of the anatomical feature is a result of______
Adaptive Radiation
33
Closely related species will have more _____ in their homologous structures
Similarities
34
The Pentadactyl limb of mammals is an example of a _______
Homologous structure
35
The theory of natural selection was proposed by ?
Charles Darwin (and Alfred Wallace)
36
What are the conditions for natural selection?
| according to natural selection theory
- There is genetic Variation between a given population
- There is competition for survival due to the overproduction of offspring
- Environmental selection pressures lead to differential reproduction
- Organisms with beneficial adaptations re better suited for survival and more likely to reproduce and pass on genes
- Over generations, there is a change in the allele frequency within a population (evolution)
37
What mnemonic can be used for Natural Selection?
ICE AGE
38
What does ICE AGE stand for? and what does it explain
Explains Natural Selection
I : inherited variation
C : competition
E : environment pressures
A : adaptations
G : genotype frequency
E : evolution
39
Natural selection can only occur if there is _____ among members of a species
Variation
40
What are the 3 main sources of variation
Sexual Reproduction
Mutation
Meiosis
(SMM)
41
Describe MUTATION
A gene mutation is a change in the base sequence of a section of DNA coding for a particular characteristic / trait
- New alleles are formed via mutation
42
Which two ways can MEIOSIS promote variation within a species?
1) Crossing over
| 2) Random Assortment
43
Briefly explain CROSSING OVER
- Occurs via synapsis during Prophase 1
- Homologous chromosomes connect via chiasmata to form bivalents (or tetrads)
- Chiasmata represent the points where genetic information has been exchanged
- The non-sister chromatids that have exchanged DNA are called recombinants.
44
Briefly explain RANDOM ASSORTMENT specifically in humans.
- During metaphase 1, homologous pairs line up in a random orientation
- This means there is an equal chance of a resulting gamete containing either the maternal or paternal chromosome
- As humans have a haploid number of 23, there are 2^23 gamete combinations (over 8 million possible gamete combinations)
45
Explain Sexual Reproduction
Sexual reproduction fuses gametes from a paternal and maternal source, resulting in offspring with a combination of traits
Because fertilisation is random, offspring will receive different trait combinations every time, resulting in near infinite genetic variability.
46
Populations will tend to produce ____ offspring than an environment can support
more
47
What is the consequence of a overproduction of offspring?
A struggle for survival
48
When there is an abundance of resources a population can achieve its ________
biotic potential
| a maximum growth rate) (J-Curve
49
More offspring means less resources are available to other members of the population is an example of what?
Environmental resistance
50
Competition for resources will lead to an increase in mortality as populations reach a _________
Carrying capacity
| S-curve
51
Biotic potential VS Competition
| on a graph which curve is exponential and which curve increases than levels put?
J curve - Biotic potential is exponential
| S curve - Carrying capacity. Increases fast than levels out
52
What are Selection Pressures
Selection pressures are external agents which may affect an organisms survival.
Organisms that are more likely to survive are more likely to reproduce and pass on genes
53
What are examples of selection pressures?
```
DENSITY DEPENDENT (lot of animals living close)
Predators
Available resources
Nutrient supply
Disease
Accumulating wastes
```
DENSITY INDEPENDENT (closeness doesn't matter)
Phenomena (e.g. fires)
Abiotic factors
Weather factors
Mnemonic: PANDA PAW
54
What are ADAPTATIONS
Characteristics that make an organism suited to its environment
55
What are the 5 types of adaptations?
Structural ( e.g. neck length of giraffe)
Behavioural (e.g. a possum playing dead)
Physiological (e.g. homeothermy (heat control))
Biochemical (e.g. lactose intolerance)
Developmental (e.g. ageing patterns)
56
How do organisms pass on genes coding for their adaptations?
Sexual reproduction / Reproduction
57
What determines the genetic variation within a population
The presence of alleles
58
Alleles for a phenotypic (a trait we can physically observe) trait may be:
Beneficial - promote survival & reproduction
Detrimental - limit survival & reproduction
Neutral - not affect survival or reproduction
59
Due to natural selection, the frequency of alleles will change across generations.
What type of alleles will become more and less common
Beneficial alleles will become more common
| Detrimental alleles will become less common
60
Allele frequencies will change in response to changing
Environmental conditions
61
What is ADAPTIVE RADIATION ?
A rapid evolutionary diversification of a single ancestral lineage
62
Adaptive radiation occurs when....
members of a species occupy a variety of niches with different environmental selection pressures
(members evolve different adaptations due to natural selection)
63
Name an example of adaptive radiation
The variety of FINSH BEAKS on Daphne Major (Galapagos Islands)
64
Give an example of Evolution in depth
PIGMENTATION OF PEPPERED MOTHS
- this moth exists in two forms: light pigmentation vs dark pigmentation
- during the industrial revolution, high levels of soot blackened the local trees
- The black moth was better camouflaged and experienced less predation
- The allele for dark pigmentation became more frequent as dark moths reproduced
- Reduced soot output has recently led to the light variant becoming more common
65
Give an example of Evolution
ANTIBIOTIC RESISTANCE IN BACTERIA
- Staphylococcus aureus exists as two strains : drug resistant VS susceptible
- If exposed to an antibiotic (methicillin), only the drug resistant strain survives
- This increases the frequency of the drug resistant allele within the population
66
What is Natural classification
involves grouping organisms according to common ancestry rather than common characteristics
67
What is a level of classification called?
TAXA
68
What does a TAXA include ?
All organisms derived from a single ancestor
69
What are the rules of TAXA ?
- Lower taxa MUST share all higher taxa
| - Lower taxa are more closely related
70
What are the advantages of natural classification?
- Able to identify organisms by a global scheme
- Shows how closely related organisms are
- Allows determination of evolutionary links
- Predictions can be made for new organisms
71
What are the disadvantages of natural classification?
- May require the reclassification of organisms when new evidence is discovered regarding an organisms evolutionary history
72
All living organisms are classified into 3 domains.
| What are they? and what goes in them?
```
EUKARYA = all eukaryotic organisms
ARCHAEA = all prokaryotic extremophiles
EUBACTERIA = common pathogenic bacteria
```
73
Compare all 3 domains
| What has a: nucleus, histones, introns and 70s or 80s ribosomes
```
Eukarya = Nucleus, histones introns and 80s ribosomes
Archaea = Introns, histones and 70s ribosomes
eubacteria = 70s ribosomes
```
74
Archaea and eubacteria are both prokaryotic, archaeal cells possess certain features that are common to eukaryotes. What does this suggest?
Suggests Archaea and Eukarya share a more recent common ancestry than eubacteria
75
List the names of the hierarchical taxa in the correct order
```
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
```
DK PCOFGS
76
Name a taxonomic example for a Animal
Human:
```
Eukarya
Animalia
Chordata
Mammalia
Primate
Hominidae
Homo
Sapiens
```
77
Name a taxonomic example for plants
Rosa acicularis:
```
Eukarya
Plantae
Angiosperms
Rosids
Rosales
Rosaceae
Rosa
Rosa acicularis
```
78
Carl Linnaeus devised what in 1735?
The binomial system of nomenclature
| a globally recognised classification scheme
79
according to the binomial system every organism has a two part name: what are they and how do you write them?
Genus : written first and capitalised (Homo)
| Species : follows in lower case (Homo sapiens)
80
Name all the Plant PHYLA what goes in them
Bryophytes (liverworts and mosses)
Filicinophytes (Ferns)
Coniferophytes (conifers)
Angiospermophytes (flowering plants)
81
What are the traits of BRYOPHYTES ?
- No 'true' leaves, roots or stems
- No vascularisation (no xylem / phloem)
- Spores in capsule at end of stalk
82
What are the traits of FILICINOPHYTES?
- Have vascularisation
- Spores in sporangia (where spores are formed) on underside of leaf
- Have large leaves divided into leaflets
83
What are the traits of CONIFEROPHYTES?
- Have vascularisation
- Have seeds (found in cones)
- Leaves narrow with a thick, waxy cuticle (protective layer)
84
What are the traits of ANGIOSPERMOPHYTES?
- Have vascularisation
- Have seeds (found in fruits)
- Have flowers as reproductive organs
85
Name all Animal Phyla and what goes in them
Porifera (sponges)
Cnidaria (Jellyfish and anemones)
Platyhelminthes (flatworms & tapeworms)
Annelida ( earthworms and leeches)
Mollusca (squids, slugs and snails)
Arthropoda (insects, spiders, etc)
Chordata (vertebrates)
86
What are traits of PORIFERA?
- Possess an asymmetrical body plan
- Have no mouth or anus (have pores)
- May have spicules (pointy things) for structural support
87
What are traits of CNIDARIA?
- Possess radial symmetry
- Have a mouth but no anus (single opening)
- Has tentacles & stinging cells (cnidocytes)
88
What are traits of PLATYHELMINTHES?
- Possess bilateral symmetry
- Have a mouth but no anus (single opening)
- Flattened body increases SA: Vol ratio
89
What are traits of ANNELIDA?
- Possess bilateral symmetry
- Have a separate mouth and anus
- Body composed of ringed segments
90
What are traits of MOLLUSCA?
- Possess bilateral symmetry
- Have separate mouth and anus
- May have a shell
91
What are the traits of ARTHROPODA?
- Possess bilateral symmetry
- Have a separate mouth and anus
- Have jointed appendages & exoskeleton
92
What are the traits of CHORDATA?
- Possess bilateral symmetry
- Have a separate mouth and anus
- Have a notochord (a primitive spinal cord)
93
Vertebrates are a sub-phylum of Chordata in which the notochord forms a backbone. What are these sub phylum?
```
Fish
Amphibians
Birds
Mammals
Reptiles
```
94
What is a Dichotomous key?
A Go to Q table dividing organisms into two categories
95
Cladistics involves classifying organisms into groups of species called _______
Clades
96
What does a CLADE consist of?
A single common ancestor and all of the descendants of that ancestor
97
What is a CLADOGRAM ?
A tree diagram where branch points represent the splitting of two new groups from a common ancestor.
98
What are branch points on a cladogram called and whats their purpose?
Named NODES
They represent speciation
The more nodes between groups = less related
99
Historically, cladograms were generated based on shared structural characteristics. Why is this method limited?
- Related species may have morphologically distinctive features (homologous structures)
- Unrelated species may have morphologically similar features (analogous structure)
SO, structural characteristics are NOT a reliable indicator of evolutionary pathways
100
what are the differences between homologous and analogous structures ?
Homologous:
Structure - look different
Cause - due to different selection pressures
Ancestry - DO share common ancestry
Evolution - Divergent (adaptive radiation)
Example - Pentadactyl limbs (in vertebrates)
Analogous:
Structure: Look similar
Cause: Due to common selection pressures
Ancestry: do NOT share a common ancestry
Evolution: Convergent evolution
Example: Fins (dolphin VS shark)
101
Cladograms are now being generated by___________
comparing DNA or amino acid sequences
More differences: species less closely related
Amino acid differences will accumulate slower than DNA differences (due to degeneracy)
102
what is mtDNA
Mitochondrial DNA
- Inherited maternally (more direct lineage)
- It lacks recombination (as mtDNA is circular)
- Has a relatively stable (and high) mutation rate
103
what is mtDNA used for?
Comparing species that are closely related
104
Describe the concept of the MOLECULAR CLOCK
Some genes or protein sequences may accumulate mutations at a constant rate.
The time divergence can be calculated based on the total number of mutations.
105
Analogous structures (convergent evolution) do NOT REPRESENT _______
common evolutionary descent
106
Taxa may be reclassified if molecular data suggests_______
alternate evolutionary pathways
107
Give an example of plant reclassification
Species in the Figwort family have been reclassified based on CHLOROPLAST DNA
108
Give an example of animal reclassification
The Homininae sub-family was created to group gorillas and humans together
