nature c4.2

Question 1

almost complete depletion of large animals and
the creation of strangely “empty” habitats
• Powerful motorized fishing boats and enormous
factory ships harvest fish from the world’s oceans and
sell them on the global market
• Such … by humans is estimated to
threaten about one-third of endangered mammals
and birds (IUCN 2004)
• Traditional societies prohibitions against harvesting female, juvenile, and
undersized animals
– Certain seasons of the year and times of the day hunters are extracting animals at a rate six or
more times greater than the resource base can
sustain.

Answer 1

Overexploitation

Question 2

Worldwide trade in wildlife is valued at over $10 billion per year
• many declining species are listed as protected
– demand for sea horses (Hippocampus spp.) in China (Fig 4.17) as traditional medicine (19 million animals)
– each year Indonesia exports the frog legs of
roughly 100 million frogs to France and other
western European countries for luxury meals

Answer 2

International wildlife trade

Question 3

harvesting for commercial purpose

Answer 3

Commercial harvesting

Question 4

the greatest amount of a resource that can
be harvested each year and replaced through population growth without
detriment to the population

(tham khao bang slide)

Answer 4

maximum sustainable yield

Question 5

blue whale (Balaenoptera musculus) since 1967
and the northern right whale (Eubalaena
glacialis), since 1935
• gray whale (Eschrichtius robustus), appear to
have recovered (Table 4.4)

Answer 5

International Whaling Commission

Question 6

international agreement between governments. Its aim is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.

Answer 6

Convention on International Trade in
Endangered Species (CITES)

Question 7

species that occur outside their natural ranges because of human activity (Exotic species)
– spread and increase in abundance rapidly,
sometimes at the expense of native species
• displace native species through competition for limiting resources
• many natives are no longer able to persist (Figure 4.18)
– Globally, over half of all recent animal extinctions
are attributable in whole or in part to the effects of
these species, (IUCN database)

Answer 7

Invasive Species

Question 8

The abundance of northern bobwhites (Colinas virginianus) in Texas
has been declining over a 20-year period following the arrival of the exotic ….

Answer 8

red fire ant

Question 9

Numerous species of fish (trout, bass, carp)

Answer 9

European colonization

Question 10

agri, horti, aqua

Answer 10

Agriculture, horticulture, aquaculture

Question 11

Large ships may hold up to 150,000 tons of ballast water (320 km
offshore)

Answer 11

Accidental transport

Question 12

Europe has over 1000 nonnative species, of which about 10% have known ecological or economic impacts
– The introduction of just one exotic species to an island may cause the local extinction of numerous native species.
• The brown tree snake (Boiga irregularis) has been introduced onto a number of Pacific islands, => endemic bird populations
– the arrival in 1988 of the zebra mussel in the Great Lakes from
Russia (Fig 4.19b) => the aquatic communities it encount

Answer 12

Biological control

Question 13

Why are certain exotic species able to invade and dominate

new habitats and displace native species so easily?

Answer 13

Better suited for
human altered
environment =>
fragmented forests,
suburban
development,
garbage

Question 14

Control of invasive species:
most serious threat facing the biota of the
U.S. national park system
– reducing the rate of their introduction needs
to become a greater priority for
conservation efforts (Figure 4.20)

Answer 14

A program of biological control
+ careful monitoring after introduction of the control species
+ physical removal, trapping, and poisoning
+ Training citizens and protected-areas staff to
monitor vulnerable habitats

Question 15

as a result of human activities and interaction with
humans
– a major threat to many endangered species and
ecosystems
– ….. may be the single greatest threat to some rare
species
– interaction with humans and their domestic animals
exposes wild animals to diseases never previously
encountered
– that can reduce the size and density of wild populations
(Fig 4.21)

Answer 15

Disease

Question 16

is another such disease that is
currently killing millions of bats across the eastern
United States
• killed when the fungus causes skin irritation and the bat
wakes up in midwinter instead of in spring, depleting its
energy reserves and subsequently starving to death

Answer 16

White nose syndrome

Question 17

1. both captive and wild animals “in dense populations” may face increased direct pressure
   from parasites and diseases
2. the indirect effects of “habitat destruction” can
   increase an organism’s susceptibility to disease
   • the increased incidence of Lyme disease and other
   tick-borne pathogens
   • linked to the local abundance of certain host rodent
   species and the overall loss of local species diversity
   (Figure 4.23).
3. human-induced “changes to the environment”,
   the increased level of international travel, and
   globalization of the economy

Answer 17

Three principles of epidemiology

Question 18

one of the main hosts for Lyme disease, increases in
abundance in habitat fragments created by suburban
development.

Answer 18

A white-footed mouse

Question 19

which can be up to 3 mm in
length, can transfer Lyme disease to a human after
acquiring the disease from an infected animal

Answer 19

A black-legged tick,