Chap 10

Question 1

In order to manage declining or endangered species we must have an understanding of__________?

Answer 1

sustainable population sizes

Question 2

Minimum viable population (MVP)

Answer 2

the smallest isolated population have a 99% chance of remaining extant for 1000 years despite the foreseeable effects of demographic, environmental, and genetic stochasticity and natural catastrophes

Question 3

How small is too small?

Answer 3

To answer we need to figure out the MVP (make sure we have a high probability that a population will survive for a long time), starting point for calculating how small is small

Question 4

MVP allows us too…

Answer 4

quantifiably estimate how large a population must be to ensure long-term survival

Question 5

A review of 200 studies found that most MVP’s for long time periods are…….

Answer 5

3,000-5,000 individuals

Question 6

For species with highly variable population sizes, protecting a population of __________ individuals would be safer

Answer 6

10,000

Question 7

Many endangered species have population sizes __________ than these recommendations

Answer 7

much smaller

Question 8

West African Elephant ex.

Answer 8

1/2 off 23 isolated elephant pop. have fewer than 200 individuals

Question 9

Michigan Isle Royale wolf ex.

Answer 9

wolf pop on Isle Royale fluctuates around 20 and currently only 8 adults of breeding age and no pups

Question 10

Channel islands bird ex.

Answer 10

only populations with >100 breeding pairs had a >90% chance of surviving 80 years

Question 11

Minimum Dynamic area (MDA)

Answer 11

the area of suitable habitat necessary for maintaining the minimum viable population

Question 12

Minimum Dynamic area can be estimated from…..

Answer 12

the home range size of individuals and colonies

Question 13

MDA Africa ex

Answer 13

studies suggest that 100-1,000 km2 are needed to maintain small populations

lg carnivores require 10,000km2 reserves

Question 14

MDA the amount of _________ needed to keep the MVP viable

Answer 14

good habitat

Question 15

Small populations are subject to rapid declines and extinctions for 3 main reasons

Answer 15

1. loss of genetic variability
2. Demographic fluctuations
3. Environmental fluctuations

Question 16

Allele

Answer 16

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome

Question 17

Allele genetic diversity

Answer 17

1 allele no diversity
2 allele little diversity
10+ lots of genetic diversity

Question 18

Genetic drift

Answer 18

the change in the frequency of an allele in a population due to random sampling

Question 19

Genetic drift cont.

Answer 19

opposite of natural selection (no selecting about it) its random loss, weak at large pop size, very strong at small pop size.

Question 20

Effective population size (Ne)

Answer 20

The size of a population as estimated by the number of breeding adults

assumes males and females are all breeding adults, are equal in number, and all contribute equally to the next generation

Question 21

Effective population size cont.

Answer 21

always smaller; the number of individual in pop that are actually breeding and contributing to the next generation

Question 22

heterozygosity

Answer 22

the proportion of individuals that inherited 2 different alleles for a particular gene.

the higher it is the better the genetic health of the population

Question 23

heterozygosity can be calculated using the following equation:

Answer 23

H=Ht/Ho=[1-1/(2Ne0]

eg. a population of 50 breeding individuals would retain 99% of its original heterozygosity after 1 generation

H=[1-1/(2*50)]=1.00=.01=.99

Question 24

Heterozygosity remaining after t generation is:

Answer 24

Ht = H^t

eg. after 2 generations, our population of 50 would have a heterozygosity of:

H2=0.99^2=0.98

Significant losses of genetic variability can occur quickly if the population is small

Question 25

Inbreeding depression

Answer 25

a condition that occurs when an individual receives two identical copies of a defective allele from each of its parents

Question 26

Inbreeding depression leads to the.....

Answer 26

the expression of deleterious alleles

Question 27

inbreeding depression results in......

Answer 27

higher offspring mortality, fewer offspring, offspring that are weak, sterile or have low mating success

Question 28

Loss of genetic diversity through _______ and ______ can be devastating for populations

Answer 28

genetic drift and inbreeding

Question 29

genetic rescue

Answer 29

Improved population fitness that results from intentional interbreeding with immigrant individuals eg. Florida Panther had low levels so brought females from Texas subspecies and released them

Question 30

Population fluctuations | Ne

Answer 30

affected by many factors may also vary over time especially true for certain species, such as butterflies and annual plants in a fluctuating population falls between minimum and maximum population sizes

Question 31

Ne equation

Answer 31

Ne= t/(1/N1 + 1/N2+....+1/Nt) a single year of a small population size will drastically lower Ne

Question 32

Population bottleneck

Answer 32

pronounced drop in population size followed by a population recovery

Question 33

In a population bottleneck

Answer 33

rare alleles are lost if no individuals possessing those alleles survive and reproduce the resulting decline in heterozygosity leads to a drop in the average fitness of the population

Question 34

Founder effect

Answer 34

when a few individuals leave one population to establish a new population a special category of bottleneck

Question 35

Stochasticity

Answer 35

random variation leading to uncertainty of outcome

Question 36

Demographic stochasticity

Answer 36

chance variation in the sex ratio of offspring or the survival and reproductive success of individuals can prevail over what is expected on average

Question 37

stochasticity and demographic stochasticity are.....

Answer 37

esp important for small populations

Question 38

Allee effect

Answer 38

a correlation between population size or density and the mean individual fitness (often measured as per capita population growth rate) of a population or species

Question 39

Allee effect: if population density is very low......

Answer 39

finding a mate can be very difficult or impossible in the population density of plants that require pollination is very low, then pollinators may not visit them or the likelihood of getting pollinated by the same species is low

Question 40

Environmental stochasticity

Answer 40

random variation over time in environmental conditions that affect reproductive or survival of individuals

Question 41

Environmental stochasticity not as dependent on....

Answer 41

population size as demographic stochasticity

Question 42

Environmental stochasticity is more dependent on...

Answer 42

size of geographic range of a species

Question 43

Extinction vortex

Answer 43

the smaller a population becomes, the more vulnerable it is to further demographic variation, environmental variation, and genetic factors that tend to lower reproduction, increases mortality rates, and so reduce population size even more, driving the population to extinction