Genetics

Question 1

What is genetic variation essential for and how is it shaped?

Answer 1

Genetic variation is essential for species persistence. It shapes population processes such as isolation, connectedness, declines, etc.

Question 2

What are allozymes?

Answer 2

Protein was extracted and run on some form of gel that allowed the separation of alleles.
This requires fresh tissue, is slowly evolving, and may be under selection.

Question 3

What are the strengths of mtDNA variation?

Answer 3

Easy to reconstruct relationships among mtDNA alleles.
These relationships can be plotted over geography.

Question 4

What did mtDNA give rise to?

Answer 4

The field of phylogeography
- Permits identification of distinct lineages.
- Insight into a species history
- Often used for species identification/ DNA barcoding
- mtDNA is maternally inherited

Question 5

What is a microsatellite in genetics?

Answer 5

Genotyping aka DNA fingerprinting.

This meant we could move to studies at the individual level.

Question 6

What is the process of microsatellite genotyping

Answer 6

1. Simultaneous sequencing of thousands/ millions of DNA fragments.
2. Permits analysis of 1000s of loci
3. increased statistical power
   - Gives the ability to survey both neutral loci and loci under selection.

Question 7

What can species identification & Assignment be used for?

Answer 7

Wildlife forensics -
- To identify legally protected
species.
- Is the sample from a captive-bred or wild-caught individual?
- Is the sample from a specific population or geographical region?

This can reveal illegal harvesting and smuggling.

Question 8

How is genetic variation shaped?

Answer 8

Gene flow= Dispersal
Genetic drift = Population size
Mutation = Time
Natural selection = Local adaptation

Question 9

what do models allow us to do?

Answer 9

To test hypotheses
To generalise results
To predict how a system will operate in the future.

Question 10

What does the Hardy-Weinberg principle assume?

Answer 10

1. Random mating
2. No mutation
3. Infinite population size
4. No natural selection
5. No immigration

Question 11

What are the different indices that can be used when quantifying genetic variation?

Answer 11

Proportion of different indices
Allele number
Allelic richness
Expected heterozygosity
Observed heterozygosity

Question 12

What affects genetic variation within a sample?

Answer 12

Genetic drift - Stochastic/ random change in genetic variation across generations.

GD is stronger in smaller populations;
Allele frequencies change more
Genetic variation is lost more quickly.

Question 13

What happens when genetic drift becomes extreme?

Answer 13

This can lead to genetic bottlenecks and inbreeding depressions.

Question 14

What is a census population size?

Answer 14

The number of individuals in a population.

Question 15

What is an effective population size?

Answer 15

An idealised population that would experience the same level of genetic drift as the population being considered.

Question 16

Why is the expected population size always smaller that the census population size?

Answer 16

There may be unequal numbers of males and females.
There may be a large variance in reproductive success
Overlapping generations may also shape Ne: Nc ratio.

Question 17

How do we measure diversity between populations?

Answer 17

Fst is the most common measure of genetic structure (Meaning isolation).
It ranges from 0-1 (0 = Complete connectivity and 1 = Compete isolation)

More connectivity / Dispersal / Gene flow = Lower Fst.

Question 18

What does Fst tell us?

Answer 18

How connected different populations are.

Question 19

What are some models of population structure?

Answer 19

Stepping stone model
- Results in a correlation between genetic distance and geographic distance (E.g., Florida Skrub jay)

Island model
All populations are connected.

Metapopulations
A group of spatially separated populations of the same species interacting at the same level (e.g., temporally).

Question 20

What are some weaknesses of Fst?

Answer 20

• It assumes markers are neutral
• Assumes equilibrium
• There is a time lag
• It doesn’t give much information about individuals

Question 21

Why is applying genetics to conservation useful?

Answer 21

1. It allows us to ascertain if populations are expanding, stable, or declining - and prioritize and assess the effectiveness of strategies.
2. Identify populations with unique/endemic genetic variants.