Week 3

Question 1

What are two approaches we take to evolution?

Answer 1

Proximate and ultimate question

Question 2

How do we define proximate questions?

Answer 2

These are how questions
It defines how traits or processes happen, it explains biological function in terms of immediate physiological or environmental factors

Question 3

How do we define ultimate questions?

Answer 3

These are the why questions
It defines how these traits were selected and the evolutionary forces acting on them

Question 4

Why is there variation between species?

Answer 4

For example ladybirds will have variation between different species due to genetic mutation meaning they’re more adapted to a habitat disguise or adapted to a certain food source

Question 5

How does variation within a species occur?

Answer 5

Genetic mutations occur within a population potentially giving an advantage or increasing a tolerance

Question 6

What are the three modes of selection?

Answer 6

Directional- selection pushes trait abundance in a particular direction likely arising in a new trait
Disruptive- selection is against the mean causing adaptive radiation
Stabilising- Both the extremes are removed meaning no evolution occurs

Question 7

What is an example of adaptative radiation?

Answer 7

The adaption of bird beaks, when in the same habitat disruptive evolution can lead to the development of different beak types that continue to move apart as new niches are exploited

Question 8

What is convergent evolution?

Answer 8

When the same trait arises in two different non related species
Example: sharks and ichthyosaurs

Question 9

What are the constraints on evolution?

Answer 9

convergent evolution occurs in different morphology trying to deal with the same environment

Question 10

What is the equation for heritability?

Answer 10

Total phenotypic variance= genetic effects + environmental effects

Question 11

What are the 3 models of population growth?

Answer 11

Geometric
Exponential
Logistic

Question 12

What is the equation of geometric growth?

Answer 12

Nt= N0 delta t
Nt= number at time
N0= Initial population size
delta= mean number of babies per person in a time slot
rearranged: delta= Nt+1 /Nt

Question 13

What are the assumptions for geometric growth model?

Answer 13

Birth rates are bigger than death rates and they’re independent of population size