Week 1

Question 1

What is natural selection?

Answer 1

The process whereby certain genetically inherited characteristics increase the chances of their carriers surviving and reproducing in a particular environment. These individuals will pass on their beneficial characteristics to the next generation

Question 2

What does selection lead to?

Answer 2

Selection leads to the accumulation of favoured variants which over a long period produce new life forms, the origin of species.

Question 3

When we study evolution which two interlinked areas are we concerned with?

Answer 3

pattern and process

Question 4

What is pattern?

Answer 4

Is what we see in the fossil record, in DNA sequences or other data

Question 5

What is process?

Answer 5

From pattern we can make inferences about the process of evolution

Question 6

Where are fossils most likely to occur?

Answer 6

Sedimentary rock in seas rivers lakes or after floods

Question 7

What are the 2 fossilisation processes?

Answer 7

Permineralisation

Natural cast process

Question 8

Describe permineralisation

Answer 8

Organic material in the bones decays and is replaced by minerals from water percolating through the sedimentary rocks.

Question 9

Describe the natural cast process

Answer 9

The bones dissolve to leave a hollow mould which may be filled later with minerals to form a solid replica of the bone

Question 10

What is bad about the fossil record?

Answer 10

It is incomplete.
It is a chance event and some animals live in places that are less conductive to fossilisation
Species with small population sizes will be poorly represented

Question 11

What are the 2 types of dating for fossils and explain them.

Answer 11

Absolute dating - the item itself is dated

Relative dating - strata above and below are dated and the item is expressed relative to these

Question 12

What are the 2 modes of evolution?

Answer 12

Punctuated and gradualism
Punctuated is where there are long periods of stasis and then rapid change.
Gradualism neo darwinism is where there is gradual change

Question 13

What is macroevolution?

Answer 13

Evolution of higher taxa.

Question 14

What are the 4 major environmental drivers of evolution?

Answer 14

Bolide impact
climate change
vulcanism
continental movement

Question 15

What are the 4 consequences of the major drivers of evolution?

Answer 15

Large scale migrations
Speciation
Mass extinction events
Adaptive radiation

Question 16

what is the order of the 11 time periods?

Answer 16

COSDCPTJKTQ
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
Triassic
Jurassic
Cretaceous
Tertiary
Quarternary

Question 17

What are the 5 mass extinctions?

Answer 17

Ordovician
Devonian
Permian
Triassic
KT boundary

Question 18

What are the two mass extinctions that are particularly important from the point of view of mammal evolution and why?

Answer 18

End permian - mammal like reptiles are superseded by the dinosaurs. A few mammal-like reptiles remained and evolved into true mammals.

End cretaceous - see the rise of the mammals following the extinction of the dinosaurs

Question 19

What more recently has influenced mammal evolution with particular implications for hominids?

Answer 19

cycles of ice ages and glaciation

Question 20

Changes in the _____ ______ have had major influences on the history of life on earth. These changes acting via ______ ______ have shaped the evolution of life on earth by mechanisms which involve ______, ____ ____ or both.
The mass extinctions at the end of the _____ paved the way for the radiation of mammals

Answer 20

physical environment
natural selection
gradualism
punctuated equilibrium
cretaceous

Question 21

what are the 5 main characteristics of mammals?

Answer 21

mammary glands
characteristic teeth (heterodont dentition)
Single lower jawbone
Three bones in the middle ear
Possess hair, sweat to cool, endotherms

Question 22

When did the major adaptive radiation of mammals occur?

Answer 22

began after the KT extinction of dinosaurs

Question 23

Late Proterozoic 650mya

Answer 23

southern polar region frozen
not a great deal of land mass
no complex life

Question 24

Late cambrian 514mya

Answer 24

Explosion of multicellular life
Trilobites common
first chordate

Question 25

Middle ordovician 458mya

Answer 25

Increase in land mass
nothing living on land yet
Gondwana in s.hemisphere
Laurasia in n.hemisphere

Question 26

Middle Silurian 425mya

Answer 26

Increase in land mass
changes to the flow of ocean currents this affects climate
coral reefs expand and plants begin to appear on land

Question 27

Early Devonian 390mya

Answer 27

Land area increasing
age of the fishes
jawed fish appear
supercontinent Pangea forming
first tetrapods appear on land

Question 28

Late carboniferous 306mya

Answer 28

adaptive radiation on land
Pangea formed
ice on southern pole
tropics forming
lots of plants on land causing oxygen levels to rise to 30%
enabled huge invertebrates to survive
first amniotes appear

Question 29

Late permian 255mya

Answer 29

No ice in southern hemisphere
early ancestors of mammals are dominating the land
Vulcanism due to closing of oceans into one larger land mass - Siberian traps form - volcanic event changes climate - extinction
96% marine 76% terrestrial
biggest of 5 extinctions

Question 30

Early triassic 237mya

Answer 30

early ancestors of mammals are around
body sizes of these ancestors have got very small because they are not dominate vertebrate, time of radiation of dinosaurs

Question 31

Late jurassic 152mya

Answer 31

land masses separating
crucial trend that affects mammal evolution during this period
first placental mammals arise
birds appear
no angiosperms

Question 32

Cretacious 94mya

Answer 32

new oceans reforming
early mammals becoming endothermic
dinosaurs getting huge and mammals small

Question 33

KT boundary 66mya

Answer 33

mass extinction event
bolide impact in yucatan peninsula
chicxulub
vulcanism event prior to bolide in indonesia forming Decan traps, this already causing dinos to decline

Question 34

Middle eocene 50.2 mya

Answer 34

africa and america are in isolation

Question 35

What are the 2 sub classes of mammals?

Answer 35

theria and protetheria - live and egg bearing

Question 36

what is the theria further divided into?

Answer 36

metatheria and eutheria

Question 37

What are monotremes?

Answer 37

Primitve reproductive system
ovoviviparous
platypus and echidna

Question 38

Describe an example of the variation in mammal reproduction?

Answer 38

Giant pandas and their altricial young. Young are very underdeveloped

Question 39

What is secondary altriciality?

Answer 39

Whilst most primates give birth to quite precocial young, after they are born they can move around have good motor skills.
Humans have developed what is called secondary altriciality. Whilst most of our relatives give birth to well developed young, humans give birth to underdeveloped young in comparison. A 1 year old humans have the same motroy skills as a neo nate chimp. During our evolutionary history we have had to reverse the trend in developmental young. The reason for this evolution is one of the evolutionary trade offs. We have done well in terms of our brain size, as we go through the human lineage to us you can see there is a massive increase in brain size. This compromises the birthing process. That brain size has increased in humans we have had to adapt by giving birth to under developed babies. Gestation in humans should be an extra year but we give birth to very altricial young compared to our relatives