Lecture 11

Question 1

What is the ultimate level of diversity (success of immigration and extinction rate) within an island is based on?

Answer 1

The size of the island and the distance from the island to the nearest source population.

Question 2

Are events such as succession predictable?

Answer 2

Although events such as succession are random in nature they occur with enough regulatory that their presence is predictable on a larger scale.
In other words, while the characteristics of individual forest patches change through time, the collective properties of the patches remain relatively constant – in a steady state because statistically speaking a forest should have the same amount of disturbance/succession through time.

Question 3

What is the leading cause of extinctions?

Answer 3

Habitat destruction.

Question 4

How many forests that were present 12,000 years ago are gone?

Answer 4

Approximately 50%.

Question 5

Do dams cause biodiversity loss?

Answer 5

Yes. Upstream, a new lake is made. Downstream, new temperatures are made - much higher than normal. Everything that lives in the river are usually ectotherms.

Question 6

What has forest clearing done in Madagascar?

Answer 6

Has resulted in a loss of 90% of the original forest cover, destroying the habitat for many unique species.

Question 7

Is deforestation worse for islands or large areas?

Answer 7

Islands.

Question 8

What are the impact of invasive species on habitats?

Answer 8

Introduced species can be a major cause of extinctions.

Question 9

Why are species introduced into new environments?

Answer 9

Intentionally for agricultural purposes (escape into the wild), intentionally for sport (e.g. sport fishing), unintentionally transported via human transport (cargo), intentionally for the pet or garden industries.

Question 10

What are some examples of invasive species?

Answer 10

Rabbits, bees, wild boars, carp, brown tree snake.

Question 11

How do invasive species cause biodiversity loss?

Answer 11

Introduced species that survive and become invasive spread and outcompete native species for space and resources.

Question 12

What are the economic costs of invasive species in Canada?

Answer 12

Estimated at 13 billion dollars per year. 120 billion/year in the US.

Question 13

What did the brown tree snake do?

Answer 13

After being accidentally introduced from New Guinea to Guan after WW2, its growth and spread of its population over 40 years decimated native bird populations (11 extinctions by 1980). The birds had evolved without such a predator (flightless birds), and the snake did not have natural predators to control it.

Question 14

What has become a laboratory for the study of human-caused biological invasions?

Answer 14

The Great Lakes.

Question 15

What has studying the Great Lakes found?

Answer 15

The introduction of fish to the Great Lakes began in the early 1800s. By 1990, 139 species had been introduced.

Question 16

What are Sea Lampreys?

Answer 16

A primitive, jawless fish native to the Atlantic Ocean that entered the Great Lakes through ship canals and locks built to bypass obstacles like Niagara Falls. Adult sea lampreys are parasitic to other fish.
Their mouth is an oral disc that is like a suction cup to attach to the side of fish. Once attached, teeth on the tongue (center of disk) rasp through the skin. An anticoagulant in saliva maintains blood flow as lamprey feeds. Host often dies from blood loss.
Each adult lamprey kills 15-40 pounds of fish in its life.

Question 17

What were the affect of Sea Lampreys on the Great Lakes?

Answer 17

Lake trout populations crashed as lamprey populations grew. In the 60s and 70s lamprey populations declined to 10% after application of lampricide - trout populations have partially recovered.

Question 18

What were the secondary effects of Lamprey invasion?

Answer 18

Once the top predators were extirpated, populations of invasive prey species like rainbow smelt and alewife increased rapidly. These invasive species then out competed native species. Extinctions of sculpin and deepwater cisco species were associated with high abundance of smelt and alewife.

Question 19

What are the effects of Zebra mussels in the Great Lakes?

Answer 19

Zebra mussels are native to the Caspian Sea, and were transported to the Great Lakes via ballast water from a transoceanic vessel. They were first discovered in the Great Lakes in the mid 1980s. Since then, they have spread rapidly to all of the Great Lakes and connected waterways in many US states, as well as Ontario, Quebec, and Manitoba. The mussels attach onto any hard substrate, including other organisms and are easily transported. A female zebra mussel can produce upwards of one million eggs per year. Establish dense populations (700,000 per m2), They may cover bottom waters or beaches with shells 30cm deep (dead mussels). Reduces species of algae and microscopic aquatic animals that are important for the food web (by mussels large filtering capacity, one L/day)

Question 20

How many organisms are carried in ballast water each day?

Answer 20

5,000.

Question 21

What are the effects of Carp?

Answer 21

Introduced to the US from China in the 70s to clear fish farm tanks. They escaped and over the last 30 years have steadily moved north on the Mississippi River. They are voracious eaters, grow very large,have devastating effects on native fish populations.

Question 22

What is a less obvious, more controversial, and less predictable human cause of biodiversity loss?

Answer 22

The alteration of biogeochemical cycles. It’s not the level of Carbon Dioxide that matters, but the rate of change and the fact that todays ecosystems have evolved to live within current CO2 levels.

Question 23

Why is Climate Change controversial?

Answer 23

Climate change
Temperature is similar in that recent trends can not be conclusively linked to human activity but are undoubtedly rising.
From a geological time point of view it is uncommon to have glaciers that persist throughout the year; so perhaps it makes sense that the Earth is warming.
Again, it is not a matter of absolute temperature but rather the rate of change and time an ecosystem needs to adapt.

Question 24

How long have ice caps been in retreat?

Answer 24

For 20,000 years. The current retreat could be part of an overall trend or due to climate change.

Question 25

How is climate change expected to change regions?

Answer 25

Change in climate and atmospheric gases will likely cause great change for organisms and biodiversity on Earth.
Many regions are expected to become warmer and/or drier; others regions are expected to become colder and/or wetter
Major changes to regional climates, possibly resulting in mass migration of organisms.

Question 26

Where are the most rapid changes occurring because of climate change?

Answer 26

In the polar regions.

Question 27

What has temperature increased by in the last 50 years?

Answer 27

2.5 degrees.

Question 28

What has the loss of sea ice caused?

Answer 28

Has decreased habitats from many organisms (e.g. Polar bears are losing habitat with the loss of pack ice.

Question 29

Why is Climate Change troubling for coral?

Answer 29

Corals require water temperatures between 25-26 degrees. Corals bleach if temperatures exceed this optimum (e,g >29 degrees). In 1988, 1998, and 2010, surface water temperatures were high and significant bleaching occurred,

Question 30

Why should we care about human causes of biodiversity loss?

Answer 30

1) We have an ethical responsibility to protect the organisms that inhabit the planet with us
2) Humans benefit from foods, medicines and industrial products derived from animals, plants & microorganisms….there are additional undiscovered benefits
3) Preserve the array of essential services provided by ecosystems (deforestation affects soil)
4) A diverse ecosystem is a healthy ecosystem (i.e. has back ups incase a species goes extinct).