Population Biology

Question 1

The extinction process can be broken down into which 2 paradigms ?

Answer 1

Declining population paradigm & Small population paradigm

Question 2

Describe the declining population paradigm

Answer 2

• Habitat destrution
• habiotat degradation
• Habitat fragmentation
• Over-hunting & live capture
  Pollution
• Invasive species
• Major dx outbreaks

Question 3

Describe the small population paradigm

Answer 3

“the effets of smallness”
-> factors causing extinction under this:
- Environmental stochasticity
- Catastrophes
- Demographic stochasticity
- Genetic deterioration

Question 4

Define environmental stochasticity:

Answer 4

random unpredictable variation in environmental factors such as temp and rainfall

Question 5

Define demogrpahic stochasticity

Answer 5

Random unpredictable variation in sex ratios, and births ad death rates

Question 6

Define Catastrophes:

Answer 6

extreme environemental events such as disease epidemics ro hurricanes

Question 7

Define Genetic stochasticity

Answer 7

Inbreeding depression, loss of genetic diversity and the accumulation of deleterious mutations

Question 8

What does stable age distribution demographic look like

Answer 8

an age pyramid with more births and young animals than old

Question 9

Demographic stochasticity will reflect events due to chance alone aka:

Answer 9

• Births, Deaths, sexr ratio at birth

Question 10

Does demographic stochasticity have a larger impact on larger or smaller populations?

Answer 10

smaller

Question 11

Define genetic diversity

Answer 11

The variety of alleles & gnotypes present in the group under study

Question 12

How is genetic diversity observed?

Answer 12

• Polymorphism
• Allelic diversity
• Average heterozygosity (expected & observed)

Question 13

Allelic diversity & heterozygosity what is it?

Answer 13

• Different forms of an allele for a particule trait (A,b, c, d which become Ab, Bc, Cd and this is heterozygosity)

Question 14

What is Expected heterozygosity also known as?

Answer 14

Gene Diversity

Question 15

What is expected heterozygosity?

Answer 15

Proportion of animals int he population expected to be heterozygous if random breeding takes place

Question 16

T/ F The ability of a population to evolve depends on allelic heterozygosity and the rate at which it does depends on expected heterozygosity

Answer 16

True

Question 17

IF a population had Hardy-Weinberg equilibrium what heterozygosity would we have?

Answer 17

The Mean heterozygosity

Question 18

What are the greatest determinants of genetic change in small vs large populations?

Answer 18

Large -> natural selection
Small -> chance

Question 19

What is the most important factor when looking at impat of genetic drift?

Answer 19

Effective population size Ne

Question 20

Wha is the effective population ?

Answer 20

The breeding population with viable offspring / portion that passes its genes into next generation

Question 21

Ne definition

Answer 21

Number of individuals that would result in the same loss of genetic diversituy, inbreeding or genetic drift if they behaved int he manner of an iealized population

Question 22

What is an idealized population?

Answer 22

A conceptual mating population with equal numbers of hermaphrodite individuals breeding in each generation, and Poisson variation in family sizes

Question 23

What are the assumptions in an idealized population?

Answer 23

• No fluctuations in population size from generation to generation
• Discere (non-overlapping) generations
• Hermaphrdite individuals
• Random mating

Question 24

What is Ne>50 mean?

Answer 24

short term - to avoid the immediate deleterious effects of inbreeding

Question 25

What is Ne>500?

Answer 25

Long term - to allow new mutations to restore heterozygosity and additive genetic variation as rapidlu as it is lost by genetic drift

Question 26

What is currently thought to be the value of Ne minimul?

Answer 26

Ne = 1000 or even 50000 to avoid loss fo diversity through drift

Question 27

What are the ffects of genetic drift ?

Answer 27

1. Alleles are lost (both adaptive, & maladaptive) 2. Drift causes loss of genetic diversity & fixation of alleles within populations

Question 28

What is Loss of diversity inversely proportional to?

Answer 28

Ne

Question 29

The effects of Sampling in every generation are ....

Answer 29

cumulative

Question 30

When do population bottlenecks happen?

Answer 30

When populations unergo susbstantial contraction - Catastrophes - Hbpitat loss - Population fragmentation When individuals in wild migrate to form new populations When individuals from the wild are caught to form captive populations When wild - to -wild translcoations take place When reintroductions take place

Question 31

TRUE OR FALSE. - Populations that have gone through bottlenecks have lower genetic diversity than those that have not

Answer 31

TRUE

Question 32

What is the effect of management interventions?

Answer 32

Can cause bottlenecks

Question 33

What does Inbreeding cause ?

Answer 33

- Inc in homozygozity & dec in heterozygosity - Inc in chance of expression of recessive deleterious alleles in phenotype

Question 34

How do we measure inbreeding?

Answer 34

Inbreeding coefficient (F) which is the probability that two alleles are identical by descent

Question 35

describe effects of inbreeding depression?

Answer 35

- Inc juvenile mortality - Reduced longevity - Reduced reproduction - Inc susceptibility to disease

Question 36

T/F inbreeding increases the risk of extinction

Answer 36

Inbreeding inc the risk of extinction - True

Question 37

Give 3 examples fo species that have experienced populations decline & extinction as a result of inbreeding

Answer 37

Bighorn sheep Florida panthers Adders

Question 38

What effects of outbreeding depression caused by crosses between different sub-species or species?

Answer 38

Offspring maladapted to both environments

Question 39

Can inbreeding and outbreeding depression occur simultaneously?

Answer 39

Yes (ex: Arabian oryx)

Question 40

What is heterosis ?

Answer 40

(hybrid vigor) - improved fitness of hybrids

Question 41

describe the extinction vortex

Answer 41

* The adverse interaction between human impacts, inbreeding & demographic fluctuation that results in a feedback loop that spirals towards extinction