Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 1 exams > Evolution > Flashcards

Evolution Flashcards

1
Q

What are 6 propositions of neo darwinian theory?

A

Reproduction
Excess - more than enough offspring
Variation - all the offspring are slightly different
Environmental selection - environment differs over time and spaitally some better adapted to one than another
Divergence - copulations become better adapted to different environments eventually results in speciation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define taxonomy and phylogeny

A 
Taxonomy = science of classifying organisms
Phylogeny = study of evolutionary relationships
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Before radioactive decay measured the world at 4.6 billion years old what other techniques were used to age the planet?

A

Sedimentary rocks, sun luminosity, sea water levels

These estimated the world to be 200 million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Starting at the pre cambrian work your way through geological time

A

Pre cambrian

PALEOZOIC 
Cambrian
Ordovcian 
Silurian 
Devonian
Carboniferous 
Permian

MESOZOIC
Triassic
Jurassic
Cretaceous

CENOZOIC
Paleogene
Neogene
Quaternary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why is the fossil record biased?

A

Some environments are better at creating fossils, i.e. Where there is more deposition than erosion. Favours marine organisms, and lowland organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give some examples of rare climactic events that could have an effect on evolution

A

Solar luminosity - sun was dimmer when the earth was first formed
Tidal ranges change due to differences in earth moon distance
Continental drift
Atmospheric changes
Milankovitch cycles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happened in the 1970s that revolutionised the production of phylogenies? Describe it

A

Cladistic analysis
Look at The characteristics of organisms and tick which have what, run through a computer. Computer runs an occams razor analysis which picks the phylgency with the fewest assumptions i.e. The most parsimonious phylogeny. Works on presence of charcters not absence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Differentate between analgous and homologus charcteristics

A

Homologus - similairty due to common ancestry

Analogus - similar due to convergent evolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Distinguish between sympleisomorphies, synapomorphies and autopomorphies

A

Symplesiomorphies - shared ancestral charcters e.g. All cats have backbone
Synapomorphies - shared derived characteristics e.g. Vertebrates have a backbone
Autopomorphies - characters unique to a taxon e.g. Enlarged cranium in homosapiens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Differentiate between mono, para, and polyphyletic

A

Monophyletic - contains latest common ancestoe plus ALL its descendants
Paraphyletic - where some species have been left out of a monophyletic group
Poly phyletic group - where two species with different common ancestors have been grouped together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the five kingdom system and the changes made to it to become the three domain system

A

Five kingdom: monera,protists animals, fungi, plants
Momera split into bacteria and archea, whilst protista split into archeozoa protista and chromoista
So three domain system of prokaryotes, archea and eukaryotes developed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where do archea often reside?

A

They are extreophiles - often living in extreme conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the three possible relationships between archea bacteria and eukaryotes

A

Archea are more closely related to eukaryotes
Two branches of archea, one closer to eukaryotes and one prokaryotes
Or
Two branches both of which are more close to eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the earth history from creation to the age of earliest fossils found

A
  1. 6 billion years ago - earth formed by gravity pulling debris together. Energy released and planet becomes molten, iron and nickel core forms whilst mangnesium makes up the mantle with silica forming the crust.
  2. 75 billion years ago - surface solidifies causing formation of first rocks e.g. Isua supracrustal group in greenland. Water doesnt condense to form oceans due to early meteorite bombardments. These also removed early organic chemicals

After 3.8 billion years the bombardment stops oceans can accumulate to form an atmosphere. Early atmosphere is made from nitrogen and its oxides as well as sulphur compunds. Earth now hospitable for life.

3.5 billion years ago - earliest fossil evidence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the panspermia theroy?

A

Organic molecules came to earth from a meterotite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the three approaches to explaining how life on earth evolved?

A

Analayse living organisms - massive cladistic analysis
Comparing duplicated genes - reach back beyond the ancestor to estimate some of the earliest genetic machinery. Identify LUCA (last universal common ancestor)
Reconstruct conditions that existed - miller Urey experiment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why is it unlikely that life on earth startedon the land?

A

UV B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define the different types of “trophs” in early life

A

Chemoautotrophs - derive energy by oxidising inorganic, compounds, C source from atmosphere
Chemohetertrophs - energy and c source from consuming organic compounds
Photoautotrphs - energy from light and c source from CO2
Photo heterotrophs - energy from light c source from organic material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe why organisms went from obligate anerobes to obligate aerobes

A

Early atmosphere had no oxygen so all organisms obligate anerobes. Lived by fermentation. Aerotolerant organisms develop who give rise to facultative aerobes (use o2 when present but they can live by fermentation). Use O2 for cellular respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe three types of evidence for prokaryotic life

A

Fossil stromatolites- not sure if it was formed biotically or not. Hypersaline bays in Australia. 1000s of stromatolites, covered in cyanobacteria below which there were anerobic bacteria. As top layer decays the anerobic bacteria moves up

Fossil microorganisms - silicified in cherts - siO2. Chalk seas have organisms growing in silica, grows around the organism and preserves them perfectly- very rare

Carboniferous matter that is identified as the product of ancient life. RuBisCo discrimination against carbon 13, alters natural ratio of carbon within rock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

From the earliest fossil evidence how long did prokaryotes dominate unchanged?

A

2 billion years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Cyanobacteria are releasing oxygen what happens to this oxygen in the early atmosphere

A

Reacted with the current gases to make CO2 NO NO2 and H2O
React with dissolved iron to form banded iron formations - BIFS
Microorganisms carry out aerobic respiration using O2 first one will have been facultative aerobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe pyritic conglomerates

A

Fools gold - iron pyrite
Eventually goes black and rots because it is unstable in aerobic conditions
Conflomerates are rocks formed by pebbles and often have iron pyrote binding them cannot have been present in aerobic conditions
Iron pyrite is not formed until 2 billion years ago

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe red beds

A

Vast deserts of red sand

Sand has a rim of iron oxides can only form in aerobic conditions, found in last 2.6 billion years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Iron conglomerates and red beds come together to suggest that oxygen accumulates in the air around 2.2-2.4 billion years ago. What does this change about the state of earth?

A

Oxygen can form the ozone layer and attenuate UV B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

When the great oxygenation event occurs what happens to the current organisms?

A

Most prokaryotes at the time are obligate anerobes and die, some are pushed to the far corners e.g. Under deep sea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Give the three main theories of how prokaryotes evolved

A

1) elaboration of cell membranes, chromome has another membrane wrapped around it that originates from the cell membrane
2) symbiosis
3) multiple symbiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the most key piece of evidence supporting symbiosis

A

Mitochondria and chlroplasts went under cladistic anlysis and came out as prokaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

When do the acritachs reach their diversity zenith? When do they suffer an extinction?

A

900 mya

850mya

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

List the ice ages and how global they were

A

765mya africa
710mya global
600mya global
542mya small global

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the advantage of sex?

A

Mutations, crossing over, independent assortment which increases variation and therefore chance of survival.
Also removes deleterious mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are the problems of sex?

A

Females useless when pregnant
Males constantly trying to impregnate
Therefore not very efficient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are four theories of why sex evolved? Why are they all wrong?

A

Method of adapting to change faster
Method of fending off diseases
Method of reparing genes
All these three are poor becuase evolution has no foresight

Historical accident - not really a theory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

When did sex evolve?

A

1.2 billion years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

When did multicellularity evolve?

A

1000 mya

Seperately several times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the most pasimonius explanation of how multicellularity evolved?

A

Most likely evolved through experimentation with colony formation - in some colonies some cells become specialised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Give the features of the metazoans

A

Multicellular body with different cell types
Collagen production
Reproductive cycles with gametes produced by meiosis
Nervous system composed of neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What four more recent advances have enabled us to understand where metazoans came from?

A

New fossils
Phylogenetic analysis
Molecular clock studies
Molecular generics of animal development

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

When were the first animal fossils found? How long do these persist for?

A

Ediacara biota
Stalk type - series of compartments quilted together flapped around
Same symmetry but laid flat
Persist for 90 million years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How did ediacara biota feed?

A

Compartments containing photosynthetic algae
Took in substances through the body wall
Symbiosis with sulphide oxidising bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What evidence is there that there were triploblasic organisms at the same time as the edicaran bacteria

A

Feeding traces found in some fossil layers at similar times to the ediacaran biota,
580mya eggs and embryos found
Outer layer of some embryos actually acritadhs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

When do small shelly fossils arise?

A

Early Cambrian- 542-530MYA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

When did the Cambrian explosion occur?

A

Middle cambrian 530-550mya

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What appears in the Cambrian explosion?

A

Representatives of all modern phyla
Arthropods
Branchiopoda
Gastropods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What four locations have fossils from the Cambrian explosion been seen?

A

Chengjiang biota in china
Sirius passet biota in greenland
Emu bay biota Australia
Burgees shale biota in canada

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

The burgess shale of rocky mountains has seen some very bizzare fossils what are these belived to be?

A

Remnants of phyla that have all together gone extinct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is key about the organisms produced in the Cambrian explosion?

A

Both hard and soft parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What caused the Cambrian explosion?

A

Environment
- snowball and slush ball earths occur within the cambrian. Mysterious final isotope excursion, very low values. Coincides with the extinction of skeletal fossils
Atmospheric o2 rose around the cambrian

Ecology
- eyes independently evolved several times causes predation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Why since the cambrian explosion have no new phyla originated?

A

Explosion of animal life meant some survive and some go extinct. Because they occupied loads of niches no new phyla can originate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What are the three theories for the history of life?

A

Creationism - all organisms put on earth at once and never changed
Transformism - all organisms were put on earth at the same time over time they have changed
Evolution - diversity very low and it increases. Species are not distinct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Name a species that mankind has created. What implication does this have on the theories of life history?

A

Primula kewensis
Interbreeding siblings - polyploidy to 36 chromomes
Suggests it cannot be creationism or transformism

52
Q

Describe how ring species disprove creationism and transformism

A

In both these theories species are distinct

Ring species demonstrate that species arent distinct e.g. Gulls around the antarctic

53
Q

How do fossils work to disprove creationism and transformism?

A

Both these theories suggest that there is greater and greater complexity of life as you go up in rock strata

54
Q

Define both evolution and gene frequency

A

Evolution = change in gene frequency

Gene frequency = proportional representation of a gene in the population

55
Q

Why doesnt mendelian inheritance cause evolution?

A

It changes genotype frequencies but not gene frequencies, the genotypes will stabalise over time

56
Q

What are the assumptions of the hardy weinburg equilibrium?w

A 
Infinite population size
No mutations
Memdelian inheritance 
No selection
Random mating
57
Q

Why is infinite population an assumption for HWE?

A

Assumes no genetic drift

58
Q

Define mutation why isnt it the main mechanism of evolution?

A

A heritable change in genetic material

Rate is between 10^-9 and 10^-4, so small that it can be considered unimportant

59
Q

Give three examples of non mendelian inheritance and explain why each cannot be used to explain evolution

A

Meiotic drive - genes that skew meisosis in their favour by distorting segregation so gametes without these genes die. E.g. Segregation disorder it changes the gene frequency but is very rare so cannot be the main mechanism for evolution

Molecular drive - genes convert different genes inti copies of themselves, again changes frequency but is very rare

Lamarckism - these charcteristics were due to environment not inheritance therefore cannot be heritable and as such are not involved in evolution

60
Q

Give the three types of selection which two are more important? Why?

A

Artificial selection - breeders selecting traits
Natural - camouflage genes reduce chance of being eaten
Sexual - traits make individual more attractive
Natural and sexual are more important as they can happen without humans

61
Q

What are the three methods to looking at adaptation?

A

Optimality approach - look at how we as humans would solve problems and see if the animals solving them have solved them optimally if so they are adapted

Comparative method - do organisms with similar lifestyles have similar traits, taxonomically different species in similar niches to see if their traits are similar. If the same you can say these are adaptations

Experimental approach - take a variable and manipulate it, the manipulation of the variable should have an impact on the adaptive value of the trait

62
Q

Give an example of the optimallity approach

A

Bee eater
Central place foraging
They either bring back bees or dragon flies, dragon flies have 3/4 times more energy than bees. Optimality suggests that bird flies further to catchdragon flies

Experimental data showed short flights had a higher proportion of bees and larger flights have more dragonflies

63
Q

Explain why gen drift, mutation, molecular and gen drift cannot be methods of adaptation

A

The change in gene frequency is random and therefore it cannot be mechanism to make them adapted

64
Q

What is the main counter evidence to the inheritance of acquired charcteristics?

A

Inheritance of negative traits e.g. Broken bones of ancestors

65
Q

What are the three nessacary factors to enable susceptibility to selection?

A

Multiplication
Variation
Inheritance

66
Q

Describe the experiments by bumpus on house sparrows

A

136 sparrows weighed before a storm
Dramatic storm
Only 72 of the 136 had survived
Compared survivors to the original sample
Mean size didnt change - shows stabalsing selection

67
Q

Describe disruptive selection using the example of batesian mimics

A

Model is distasteful whilst the mimic is palatable. Mimic pretends to be the model.

Models are very colourful, negative associations with those colours e.g. Black and yellow stripes means getting stung

Mimics wont sting

Frequency effects how much this works, if their are to many mimics then the mimicry doesnt work since predators are more likely to come into contact with the mimic. Forces mimics into smaller populations.

Papilio dardanus butterfly has overcome this, different females become mimics of different models. They have different colours, colours in the middle i.e. The mean are not favoured since they don’t mimic any model. Hence the mean values are removed from the population and the extremes are favoured

68
Q

Give two ways of detecting selection

A

Look for correlations between characteristic variation and environment
Look for differences in fitness

69
Q

Describe the experiments done on cepaea nemoralis

A

Lots of variation in its shell colour and banding dependant on where it lives
Mainly predated on by the song thrush where it takes snails to an anvil and smashes them
Put snails from grassland into woodland and vice versa
Saw those who were in the wrong environment had a selective disadvantage

70
Q

Describe the case of human induced selection involving DDT

A

DDT is a pesticide that eradicates fleas and pests, its dangerous but less so than arsenic and petrol and it was very effective
Within 18 years 137 resistant species had evolved

71
Q

How can fitness be measured?

A

Lifetime reproductive success
Which encompasses both survival and reproduction
Reproduction is split into fertility and fecundity
Also defined by how many mates an individual can get
Survival fecundity and fertility are all selected for naturally
Reproduction and number of mates are sexually selected

72
Q

Define altruism give some examples

A

Benefits other individuals at their own cost
Worker bees not reproducing
Guard bees who die when they sting something

73
Q

Give methods that could cause altruism to arise

A

Not really altruism- e.g. Monkeys calling actually panics others making them more vulnerable (no data to support this)

Behaviour is reciprocated - e.g. Vampire bats regurgitate blood and give it to others

Adaptations evolve for the good of the species - group selection, a group behaving altruistically will out compete one that isn’t.

Selection occurs at the gene level not the individual - only alturistic to those with the same genes

74
Q

Why cant evolution be due to group selection?

A

Vulnerbale to “cheating” i.e. Take advantage of the alturism but not comperate. This will be massively beneficial and hence this individuals fitness will be far higher enabling it to reproduce more meaning the cheating gene is spread more. Group selection occurs at the generation of the group which is far longer than that of the individual therefore any mutation will spreadin the individuals before group selection can work on it

75
Q

What is W.D. hamiltons rule of kin selection?

A

Altruism will occur when rb>c
Where r = coefficient of relatedness (proportion of genes that are the same)
C = cost of altruism to altruist
B = benefit of altruism to recipients

76
Q

What is macroevolution?

A

Evolutionary changes at the population level

77
Q

Describe gene flow

A

The exchange of genes between populations as a result of movement and interbreeding of individuals. Gene flow counters disruptive selection.

78
Q

What conditions in terms of selection and gene flow must be present for speciation to occur?

A

Disruptive selection and low gene flow

79
Q

What are the two changes that occur for speciation to happen? What are the two types of speciation and in which order do these happen?

A

Divergence - species adapt to different environments
Reproductive isolation - populations cannot interbreed
Allopatric isolation - isolation then divergence
Sympatric isolation - divergence then isolation

80
Q

In terms of allopatric speciation once the barrier has been removed what tells you how different the two species are?

A

The size of the hybrid zone, smaller = more different

81
Q

Give an example of island endemics in the canary islands

A

Chaffinches are more blue on the islands than the main island

82
Q

In sympatric speciation the _______ alone must be enought to overcome the __________. It is initially _____________ isolation, since the hybrids are less fit. Then ____________ die out, once mating is ____________ then pre zygotic selection can occur.

A 
Disruptive selection
Gene flow
Post zygotic 
Random mating females
Non random
83
Q

Give two examples of disruptive selection overcoming gene flow

A

Argostis tenuis on slag heaps
- slag has toxic metals, has identical grass all over
- grass on slag can overcome toxic chemicals
Hybrid offspring on normal grass are outcompeted since they produce unnecessary substrates e.g. Amino acids.
Hybrids on the slag will be outcompeted by non hybrids as they are less efficient

Lacewings - chrysoperia
- carnea is lighter than downesi and they both live in locations to suit
- can be cross bred to produce viable offspring
Two species have vastly different breeding periods, downesi breeds in spring time whilst carnea breeds in summer. Summer produces carnea and winter produces downesi as these colours ar better suited to their respective environment.

84
Q

What are the two patterns of macro evolution?

A

Gradualism - one form speciate into two forms creating a bifurcating tree. Evolution is a constant rate

Punctuated equilibrium- a single species suddenly speciates in between events there is stasis. Suggests another genetic revolution other than natural selection

85
Q

What is the evidence for punctuated equilibrium? Why is the evidence not perfect?

A

Fossils stay the same for millions of years then suddenly new forms appear with no intermediates
But fossil record is incomplete and has large gaps and only represents small amounts of time. Strata are only up to 10% of size they should be.

86
Q

Give an example to show how evolution can occur rapdily

A

Homo erectus had a 920ml brain size which evolved to our hrwin size of 1.4L in 20,000 years. Estimated only one small brained child needed to die every generation hence very plausible

87
Q

Give examples of how organisms can undergo large periods kf stasis

A

Nortilus - 550million years looked the same
Lingula looked same since cambrian
Horseshoe crabs

88
Q

Using anteater like animals show convergence in evolution

A 
Anteaters from south America
Aardvark from Africa 
Echidna from Australia 
Pangolin from south east asia
All four very unreleated but have a long snout with reduced teeth. Strong limbs

All have very similar lifestyles so have evolved similar traits

89
Q

What is an adaptive radiation?

A

Where one species evolves into many species, may occur through the evolution of a new characteristic enabling exploitation of new land. E.g. The amniote egg

Or where competition is removed e.g. Extinction of dinosaurs, niches became empty and were filled by small mammals who could undergo adaptive radiations

Or where new land is explored e.g. An island e.g. Honey creepers in hawaii all evolved from a common ancestor but have different morpholgies

90
Q

What are the three levels of extinction?

A

Local - e.g. Wolves from UK
Species - whole species becomes extinct e.g. Dodo
Mass extinction - period in geological time when extinction rates foes above background rate

91
Q

What percentage of species have gone extinct?

A

99%

92
Q

What are three ideas why extinction occurs? (Don’t explain them)

A

Racial senescence
Competition
Environmental change

93
Q

Describe the idea of racial senescence as a means of extinction

A

Species undergo a lifecycle like individuals aka orthogenesis.
Idea that once evolution starts it cannot be stopped

94
Q

Give three examples of species suggested to have undergone racial senescence

A

Irish elk - common in last glacial period. Large antlers initially advantageous for sexual selection but became deleterious since evolution moves under its own momentum the antlers became bigger and bigger until they died. In reality large scale climate change occurred at the same time that killed the elks as well as forests growing.

Gryphaea - hinged jaw curls to the point it traps air valves preventing them from opening

Ammonites - smooth shell to help aerodynamics in some spikes started to arise. Divergent selection causing bizarre versions to form close to their extinction

95
Q

Why is the idea of racial senescence faulty?

A

No proposed mechanism

At odds with natural selection

96
Q

Give examples of dramatic environmental change that could lead to extinction

A

Movement of land masses

Continental collisions mammals

97
Q

Describe the distribution of mammals and marsupials in north and south america over time

A

Mammals originally in north America, marsupials in south america. Land bridge forms causes south america to become more temperate i.e. Like the north. Mammals outcompete marsupials.

98
Q

Say when and where the last 5 mass extinctions have taken place

A

Ordovician - 440MYA - marine invertebrates
Devonian - 370MYA - marine invertebrates and fish
Permian - 245 MYA - marine invertebrates and fish
Triassic - 210MYA - freshwater fish and above
Cretaceous - 65MYA - dinosaurs, pterosaurs and marsupials

99
Q

Why did the dinosaurs go extinct? Give four theories

A

Angiosperms produce nictine and hallucinogenic chemicals that kill all
Too large to copulate
Egg eating mammals
Asteroid impact

100
Q

Give evidence for the asteroid impact theory for dinosaur extinction

A

Gulf of mexico has large enough crater
Band of rock in the KT boundary (between cretaceous and teritary) below we find dinosaurs above none. Rocks full of iridium which is rare on earth but common on meteors. Would have caused a nuclear winter that killed all the plants

101
Q

Give releatedness values for a cousin and a sibling

A 
Cousin = 0.125
Sibling = 0.5
102
Q

What is meant by green beard genes?

A

Where an altruism gene is linked to an obvious phenotype, means they dont have to be related. The two genes must be closely linked on the genome.

103
Q

Give two examples of real life examples of green beards

A

bb queens die naturally
BB queens killed by Bb workers only heterozygotes survive
Odours used to distinguish between the two

Bluebeard lizards
Unrelated males form alliances to protect territory
Only those with blue throat
One male has no offspring (true altruism)
Genes for cooperation and throat colour are linked

104
Q

Why are green beards usually unstable populations

A

Green beards can cheat i.e. They posses the green beard but don’t behave altruistically

105
Q

What is a method selfish genes can use to overcome competition from other genes? Why is this ‘selfish’?

A

Meiotic drift
E.g. Segregation disorder in drosophila
- meiosis doesnt work normally
- more sperm (90%) have the segregation gene
- distorts segregation
Reduces fitness since fewer sperm are produced but the selfish gene is winning as more copies of it are produced

106
Q

Use Darwins finches as an example of evolution in real time

A

Evolution of bill size
G magnirostris appears after G fortis
When this happens G fortis have reduced beak sizes
G magnirostris has a larger beak and so fills niche of G fortis individuals with larger beak. G fortis with small beaks are favoured since they have less competition.

107
Q

Describe bow artificial selection or exploitation can cause evolution in observable time

A

Bighorn sheep in USA
- trophy hunted
- large horns wanted
In 30 years mean horn sized reduced from 50cm to 40cm

Body size and maturity in Cod
- cod caught in large numbers
- larger fish selected for by net sizes
Fish have indeterminate growth, grow differently temperature dependant. Need to reach a threshold to reach sex maturity. Larger and older are removed via artificial selection therefore sexual maturity 1987 occurs at 4 years old but 5 was the avergae in 1980

108
Q

Climate change can lead to three things in terms of species

A

Extinction
Migration
Evolution

109
Q

Describe the case study of myxomatosis on rabbits

A

Rabbits introduced to Australia in 1859, enormous capacity for reproduction and became pests.
Myxoma virus introduced and killed 99% of population
Second epidemic introduced when population grew back killed 90% of the population
Third epdiemic killed 40-60%

The death of the hosts was stopping the spread of the parasites
Parasites were changing, reduced virulence meant they could spread more and infect more

110
Q

What is phylodynamics?

A

Sample viruses in humans and put an evolutionary history together

111
Q

What is meant by a plex mate phylogeny ?

A

Species are formed and go extinct rapidly
Forms many different types of species
E.g. Influenza

112
Q

How are viruses often mapped? Describe the mapping for measles and influenza

A

Mapped by antigenic protein coating
Different protein coats throughout history of influenza
Typically only two types of protein coats occur at once
Host eventually becomes immune and hence its protein coat becomes ineffective

Measels sees very little selection and is spread more randomly (consequence of the school calendar)
Trend in influenza is caused by evolution

113
Q

Give some examples of animals that have gone extinct, what do they all have incommon

A

Dodo - large flightless pigeon
Greak ork - huge flightless bird
Chinese river dolphin
All the above are very unusual organisms

114
Q

What are we limited in when it comes to conervation?

A

Money and reources - cant conserve every species

Not enough people to conserve every habitat

115
Q

Describe phylogenetic niche conservatism

A

Species inherit their niches from their ancestors, closely related species are ecologically similar and share life history traits.
If the environment is affected in this area all these species are likely to be at risk
Therefore closely related species will share similar responses to environmental change

116
Q

Describe the experiments purvis et al did on niche conservatism

A

Looked at IUCN threat levels
Looked at life history variables and ecological variables
Did stats tests to look at if there is niche conservatism and wether it correlates with extinction likelyhood.

117
Q

Give the features that correlate with threat of extinction in carnivores

A

Size of geographic range
Gestation time
Trophic level
Human footprint

118
Q

Give the features that correlate with extinction threat in primates

A

Size of geographic range
Body size
Population density
Human density

119
Q

What does phylogentic niche conservatism eventually mean?

A

IUCN threat likely to be similar in close relatives

120
Q

Where is niche conservatism lower? What impact does this have?

A

Niche conservatism greater in tropics hence evolution is slower here.

121
Q

What do studies in niche conservatism allow us to do?

A

Prioritise

  • shows us which groups will most likely be able to cope with change
  • some areas contain more unique species than others
  • unequal distribution of species
122
Q

Define phylogenetic diversity

A

Captures the number of species and their individual history. Maps onto evolutionary distinctiveness

123
Q

Communities with _____________ are more robust so it becomes less likely that they will go extinct

A

Higher phylogenetic diversity

124
Q

How should we prioritise on conservation from a niche conservatism point of view

A

Record species present at set areas
Generate a phylogeny of the species
Calculate phylogenetic diversity
Prioritise accordingly

125
Q

Describe the studies of moritz et al (2006) on frog conservation

A

Conserving species richness and phylogenetic diversity in austrlian habitats
Mismatch between richness and diversity
Area with high both is best since you are saving many organisms and the ecosystem is robust

126
Q

Describe the edge project

A

Evolutionary distinct and globally endangered
Puts data together to work out which organisms are evolutionary diverse
E.g. Platypus is evolutionary diverse but is of least concern
Cuban solemodom is diverse but is endangered

Semester 1 exams (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions