Conservation Biology Twu Exam 3 Chapter 11

Front 1

Minimum Viable Population
pg 248

Back 1

MVP. The number of individuals necessary to ensure the long-term survival of a species.
Smallest isolated population having a 99% chance of remaining for 1000 years.

Front 2

Back 2

Population Size v. Extinction Rates

Front 3

Predicted MVP for most populations?
pg 249

Back 3

100 or over.
<50 die off within 50 years.

Front 4

Back 4

Minimum Viable Population size

Front 5

Minimum Dynamic Area
pg 250

Back 5

MDA. Area of suitable habitat necessary for maintaining the MVP

Front 6

3 Main reasons small populations are subject to rapid decline and local extinction:

Back 6

1) Loss of genetic variability and related issues to inbreeding and genetic drift
2) Demographic fluctuations due to random variations in birth and death rates
3) Environmental fluctuations due to variation in predation, competition, disease, food supply and due to natural catastrophe.

Front 7

Alleles
pg 250

Back 7

Different forms of the same gene
New alleles arise due to mutations or through migration of individuals from other populations.

Front 8

Genetic Drift
pg 251

Back 8

Random process of allele frequency change.
Genetic variability is lost randomly over time through genetic drift.
Low frequency alleles in a small populations have a significant probability of being lost in each generation.

Front 9

Effective Population Size
pg 251

Back 9

Size of the population as estimated by the number of its breeding individuals
(Ne)

Front 10

Formula for proportion of Heterozygosity remaining after each generation
pg 251

Back 10

Generation- H
Effective Population Size- Ne

H= 1- 1/( 2 Ne)
Example:
Population of 50 breeding indivs
1-1/(2*50)
1-1/100
1-.01=.99
99%
An effective population size of 50 would retain 99% of its heterozygosity.

Front 11

Back 11

Genetic Variability Lost

Front 12

Ht=Ht
pg 251

Back 12

Take H from Heterozygosity equation andmultiply it by itself, this if the amount of retained heterzygosity after 2 generations

Front 13

Back 13

Heterozygosity of small v. large populations

Front 14

Mutation Rates in Nature
pg 251

Back 14

1 in 1 mil/gene/generation

Front 15

50/500 Rule
pg 254

Back 15

Isolated populations Need at Least 50 indivs and Preferably 500 to maintain genetic variability.
Empirical studies show that Actually several thousand individuals must be protected to maintain variability.

Front 16

Inbreeding
pg 254

Back 16

Mating among close relatives

Front 17

Outbreeding
pg254

Back 17

Mating with organisms outside of population or species

Front 18

Inbreeding Depression
pg 254

Back 18

When an individual receives two identical copies of a defective allele. Characterized by higher mortality, fewer offspring or weak or sterile offspring

Front 19

Outbreeding Depression
pg 255

Back 19

When organisms cant find a mate within their own species or population, may mate with "related" individuals of another species.
Results in weakness, sterility or lack of adaptability with environment.
(incompatibility of the chromosomes)

Front 20

Back 20

Relatedness v. Fitness

Front 21

Hybrid Vigor
pg 255

Back 21

When outbreeding produces a More vigorous species

Front 22

Loss of genetic variability limits a small population's ability to...
pg257

Back 22

respond to new conditions and longterm changes

Front 23

Unequal sex ratio
pg258

Back 23

When the numbers of mating males and females are unequal
Ne=[4(NfxNm)]/(Nf+Nm)
Nf-breeding females
Nm-breeding males
Ne-effective pop size

Front 24

Population flucuations and Bottlenecks equation
pg259

Back 24

Effective pop size can be calculated over a period of years using number of indivs
Ne=t/(1/N1+1/N2+1/N3.....1/N8)
Ne-effective population size
t-years
N- breeding individuals

Front 25

Back 25

effective population size in unequal sex ratio

Front 26

Population bottleneck
pg 260

Back 26

when a population is greatly reduced in size and loses its rare alleles

Front 27

Founder effect
pg260

Back 27

When a few individuals leave one pop to establish another new pop. 2nd pop has less genetic variability than the original

Front 28

Stochasity
pg264

Back 28

Random Variation

Front 29

Environmental Stochasity
pg 264

Back 29

Random variation in Biological and Physical environment, can also cause vriation in the pop size.

Front 30

Demographic Stochasity
pg 264

Back 30

Variation in Birth and Death rates among individuals and across years within a given pop

Front 31

Allee effect
pg265

Back 31

Small populations are demographically unstable because social interactions can be disrupted once a pop density falls below a certain level.
The interaction between pop size, pop density and pop growth rate.

Front 32

Back 32

Sex Ratios decline in a stressed environment

Front 33

Back 33

Extinction Rate V Population size
Effects of demographic variation, low environmental variation, and moderate environmental variation and the probability of extinction

Front 34

Back 34

Extinction Vortex