Causes of biodiversity losses

Question 1

Levels of organization of the concept of biodiversity.

Answer 1

1. Genetic diversity. 2. Species diversity. 3. Ecosystem diversity.

Question 2

What’s genetic drift?

Answer 2

Random fluctuations in the allele frequency of a population.

Question 3

What happens when there is GD in a small population?

Answer 3

Infrequently-occurring alleles face a greater chance of being lost.

Question 4

Genetic drift is common after…

Answer 4

a population experiences a population bottleneck.

Question 5

When does a population bottleneck happens?

Answer 5

When a significant number of individuals in a population die or are prevented from breeding, resulting in a drastic decrease in the size of the population.

Question 6

What led to the hypothesis that genetic drift plays a role in the evolution of new species?

Answer 6

Genetic drift can cause a new population to be

genetically distinct from its original population.

Question 7

How was the Florida Panther (Puma concolor subsp. cory) affected by GD?

Answer 7

It is a subspecies of the North American Cougar. In the 1970s, an estimated 20 Florida panthers remained in the wild.

Question 8

What threats did the Florida panther face?

Answer 8

1. genetic depletion due to habitat destruction (isolation)
2. gradual
   decline in the population size,
3. inbreeding depression

Question 9

What was the “genetic rescue” experiment in Florida Panthers?

Answer 9

In Florida in 1995, eight female pumas from Texas were
introduced to the population. Hybrids have no health
defects.

Question 10

How was the Mexican gray wolf (Canis lupus baileyi), the most genetically distinct lineage of wolves in the Western Hemisphere, affected by GD?

Answer 10

The Mexican gray wolf was extinct in the wild (USA) in 1995. All the individuals in the world today are
descendant of the few original captive wolves (survivors of a last wild population in Mexico) that
were part of the breeding program that allowed the
species to be reintroduced, so their genetic
diversity is extremely low.

Question 11

What’s the situation with the Giant Panda?

Answer 11

Giant pandas lived in forests from China to northern Burma and Vietnam, but extensive deforestation has
restricted the species to six alpine forest fragments in western China. Genetic analysis shows that they still have enough genetic diversity to recover.

Question 12

How manu populations of Giant Pandas are there today?

Answer 12

Biologists estimate that the remaining giant pandas are divided into about 25 populations with fewer than 20 individuals each.

Question 13

What is China’s approach for protecting the Giant Panda?

Answer 13

China is creating huge reforestation projects with the
money they get from renting pandas out to zoos aroundthe world. They are trying to link all the corridors where pandas live and give them new places to migrate when they need to.

Question 14

Which are the subspecies of White Rinho (Ceratotherium simum) ?

Answer 14

1. Southern white rhinoceros

2. Northern white rhinoceros .

Question 15

What was the situation of Northern white rhinoceros?

Answer 15

The northern wild rhinoceros are considered critically endangered or possibly Extinct in the wild .
Formerly found in several countries in East and Central Africa. The world’s last male northern white rhino, died in 2018 at a wildlife preserve in Kenya.

Question 16

What are scientists working on regarding northern white rhinos?

Answer 16

Scientists are working with rhino eggs, cell cultures, tissues, blood and frozen sperm samples to produce a
live northern white rhino birth—and maybe even repopulate the entire subspecies. (not done before)

Question 17

Which is he most endangered cetacean in the world, why is it endangered and where is it endemic from?

Answer 17

La vaquita (Phocoena sinus). It is threatened by bycatch from illegal net fishery and it is endemic to the northern part of the Gulf of California.

Question 18

Why did the Iberian lynx population declined in the 20th century?

Answer 18

1. Sharp declines in rabbit populations, caused
   by myxomatosis, rabbit haemorrhagic disease, and overhunting.
2. Fragmentation of grassland and forest habitats
3. Poaching

Question 19

How have numbers of Iberian lynx behaved?

Answer 19

In 2005 there were only 100, but grew to 894 in 2019. IUCN deciding that it was no longer critically in danger. It is now categorized as “in
danger.

Question 20

Name the categories of the IUCN red list (7)

Answer 20

1. Least concern
2. Near threatened
3. Vulnerable
4. Endangered
5. Critically endangered
6. Extinct in the wild
7. Extinct

Question 21

Name the criteria taken into account for categorising species in the IUCN list (5)

Answer 21

A. Population size reduction (past, present and/or projected)
B. Geographic range size and fragmentation
C. Small and declining population size and
fragmentation, fluctuations, or few
subpopulations
D. Very small populations or very restricted
distribution
E. Quantitative analysis of extinction risk
(e.g., Population Viability Analysis)

Question 22

When was the Dodo bird exctinct and where was is endemic from?

Answer 22

300 years ago. It was endemic to the island of Mauritius (east of Madagascar).

Question 23

How and when did the Great Auk go extinct?

Answer 23

In the 19th century because of:

1. Huntedfor feathers for pillows.
2. Hunted for fishing bait,
3. Museums and collectors desired their own specimens.

Question 24

How and when did the Pinta Island Tortoise go extinct?

Answer 24

It was from the Galapagos Islands. It was hunted
for food in the 19th century, and its habitat was
destroyed in the 1950s when goats were brought to the island. In 2012, the last of his kind died.

Question 25

How and when did the Steller’s Sea Cow go extinct?

Answer 25

It became extinct in 1768 after being hunted for food, fat for oil lamps, and skin to line boats.

Question 26

How and when did the Tasmanian Tiger go extinct?

Answer 26

It became extinct in the 1930s due to:
1. Excessive hunting by farmers who blamed it for
killing sheep and poultry. 
2. Loss of habitat to agriculture
3. Disease
4. The introduction of dogs.

Question 27

What is the national tree of the Easter island? (Which is extinct there but remains in some botanical gardens)

Answer 27

Toromiro Tree –Sophora toromiro

Question 28

How it the extinction rate today in relation to before?

Answer 28

The current extinction rate is 1000 times higher than natural background rates.

Question 29

Name the first 5 countries with the highest number of threatened species.

Answer 29

1. Ecuador.
2. United States
3. Malaysia
4. Indonesia
5. China

Question 30

What is “trophic cascade”?

Answer 30

It is s an ecologycal imbalance that occurs when a trophic level (species) of the ecosystem is reduced or removed.

Question 31

How is the gray wolf an example of “trophic cascade”?

Answer 31

In the 70-year absence of wolves in the Yellowstone Park, elks had become accustomed to grazing tender,
native willows without much predation risk. This lead to a decline of the willow populations, a decline of beavers due to the decline of willow and aspen, and a decline in songbirds.

Question 32

Which are the 5 primary drivers of biodiversity loss?

Answer 32

1. Habitat loss and alteration
2. Introduction of exotic species and GMO
3. Pollution
4. Climate change
5. Overexploitation of resources

Question 33

Explain “habitat loss and alteration” as a threat for biodiversity.

Answer 33

The transformation of the natural areas determines not only the loss of the plant species, but also a decrease in the animal species associated to them.

Question 34

Explain “exotic species and GMOs” as a threat for biodiversity.

Answer 34

Species originating from a particular area, introduced into new natural environments can lead to different forms of imbalance in the ecological equilibrium.

Question 35

Explain “Pollution” as a threat for biodiversity.

Answer 35

Human activity influences the natural environment
producing negative, direct or indirect, effects that alter the flow of energy, the chemical and physical constitution of the environment and abundance of the species.

Question 36

Explain “Climate change” as a threat for biodiversity.

Answer 36

For example, heating of the Earth’s surface affects
biodiversity because it endangers all the species that adapted to the cold due to the latitude (the Polar species) or the altitude (mountain species).

Question 37

Explain “Overexploitation of resources” as a threat for biodiversity.

Answer 37

When the activities connected with exploiting a renewable natural resource in a particular area are excessively intense, the resource itself may become exhausted. An example is the case of sardines, herrings, cod, tuna and many other species that man captures without leaving enough time
for the organisms to reproduce.