conservation biology chapter 5

Question 1

extinct

Answer 1

extinct when no member of the species remains alive any- where in the world.

Question 2

extinct in the wild

Answer 2

Ifindividuals of a species remain alive only in captivity or in other human-controlled situations, the species is said to be extinct in the wild.

Question 3

globally extinct.

Answer 3

e In both of the above situations, the species are also considered to be globally extinct.
extinct
and extinct in the wild

Question 4

locally extinct or extirpated when

Answer 4

Aspecies islocally extinct or extirpated when itisno longer found in an area it once inhabited but is still found elsewhere in the wild. The gray wolf (Canis lupus) once roamed throughout North America; itis now locally extinct in Massachusetts.

Question 5

ecologically extinct if

Answer 5

ifitpersists atsuch reduced numbers that itseffect on other species within itsecological community isnegligible. Tigers are ecologically extinct in most of their range because so few remain in the wild that their impact on prey populations is insignificant.

Question 6

extant

Answer 6

It is also true that species pre- sumed to be extant (still living) may actually be extinct;

Question 7

extinction debt

Answer 7

The presumed eventual loss of species following
habitat destruction and fragmentation iscalled the extinction debt (Berglund and Jonsson 2005).

Question 8

Endemic species

Answer 8

pecies found in one place and nowhere else— are particularly vulnerable to extinction (Table 5.2). Numerous endemic species of oceanic islands are in danger of extinction.

Question 9

island bio- geography model

Answer 9

This model predicts that large islands will have more species than small islands

Question 10

Vulnerability to Extinction

Answer 10

Species with a very narrow geographical range.
Species with only one or afew populations.
Species in which population size issmall.
Species that are hunted or harvested by people.

Question 11

minimum viable population, or MVP:

Answer 11

“A minimum viable population for any given species in any given habitat is the smallest isolated population having a 99% chance of remaining extant for 1000 years despite the foreseeable effects of demographic, environmental, and genetic sto-
chasticity, and natural catastrophes.” In other
words, the MVP isthe smallest population size
that can be predicted to have a very high chance
of persisting for the foreseeable future. Shaffer
emphasized the tentative nature of this defini-
tion, saying that the survival probabilities could
be set at 95%, 90%, or any other percentage, and
that the time frame might similarly be adjusted,
for example, to 100 or 500 years. The key point isthat MVP analysis allows scientists to make a quantitative estimate of how large a population must be to assure long-term survival.

Question 12

Demography

Answer 12

Demography is the statistical quantification of a popula- tion’s size, distribution, and its composition based on factors such as sex and age.

Question 13

Once an MVP size has been established for a species, the minimum dynamic area (MDA)—t

Answer 13

the area of suitable habitat necessary for maintaining the minimum viable population—can be estimated by studying the home- range size of individuals and colonies of endangered species.

Question 14

Small populations are subject to rapid decline in numbers and local extinction for three main reasons:

Answer 14

1. Loss of genetic variation and related problems of inbreeding depres- sion 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, and food supply or to natural catastrophes that occur at irreg- ular intervals, such as fires, storms, or droughts

Question 15

inbreed- ing depression,

Answer 15

a condition characterized by higher mortality of offspring; fewer offspring; or offspring that are weak, sterile, or have low mating suc- cess (Figure.5.11; Willi et al. 2006).

Question 16

outbreeding depression

Answer 16

However, when a species is rare or its habitat is damaged, individuals unable to find mates within their own species may mate with individuals of a related species. The resulting off- spring sometimes exhibit outbreeding depression in the form of weakness, sterility, or lack of adaptability to the environment.

Question 17

hybrid vigor

Answer 17

However, many studies have failed to demonstrate outbreeding depression in animals, and in
fact other studies have found some hybrids to be more vigorous than their par- ents, a condition referred to as hybrid vigor.

Question 18

effectivepopulationsize, N,

Answer 18

thenum- ber of reproductive individuals contributing to the population’s “gene pool”—is often substantially smaller than the total population size (N).

Question 19

founder effect

Answer 19

occurs when a few individuals leave a population and establish a new population.

Question 20

stochasticity,

Answer 20

Random variation, or stochasticity, in the environment can cause variation in the population size of a species.

Question 21

environmental stochasticity

Answer 21

affects all indi- viduals in the population and is linked to demographic stochasticity (or demographic variation), which is the variation in birth and death rates among individuals and across years within a given population.

Question 22

allee effect.

Answer 22

This interaction between population size, population density, and population growth rate is sometimes referred to as the Allee effect.