Population Ecology and Succession

Draw

Imagine you have a petri dish containing a single bacterium. This bacterium is able to reproduce (divide in two) every hour.

Draw a rough graph to represent population growth over the course of one day. Make sure to include axes titles!

Open Ended

After one day, your petri dish would contain 16,777,216 bacteria!

Do you think this pattern of growth can continue forever? What factors might limit the growth of your bacteria?

Draw

Your bacteria cannot continue to divide forever as certain factors (food, space, etc) start to limit population growth.

Redraw your graph of population growth, considering the effect of limiting factors.

Categorize

Options (11)

Disease outbreaks in a crowded population

Predation pressure on a prey population

Parasitic infections spreading through a population

Competition for food

Natural disasters (e.g. bushfires, cyclones)

Climate change

Human activities (e.g. deforestation, pollution)

Temperature fluctuations

Weather events (e.g. droughts, floods)

Chemical contamination

Limited availability of nesting sites for birds

Organise these options into the right categories

Density-dependent limiting factors

Density-independent limiting factors

Open Ended

A group of 20 rabbits is introduced into a fenced area containing grasses, shrubs, and trees. The rabbits are free to move around and feed on whatever plants they can find.

Over the course of several months, the population of rabbits begins to fluctuate. At first, it grows rapidly as the rabbits reproduce and take advantage of the abundance of food. But eventually, the growth rate slows down and the population levels off.

What factors might be limiting the rabbit population?

Open Ended

Additional information:

The area is relatively predator-free, so predation is unlikely to be a major factor.

The rabbits are not experiencing any significant diseases at the moment.

However, there are other animals in the area, such as deer and squirrels, that are also feeding on the same plants as the rabbits.

There has been a drought in the area, which has reduced the amount of available water and made it harder for plants to grow.

What do you think the limiting factor is now?

Math Response

The following data was obtained when monitoring mountain gorilla numbers in a nature reserve:

Captured and marked = 25 gorillas

Recaptured at a later date = 24 gorillas

Number of marked individuals in recaptured sample = 8 gorillas

Estimate the size of the mountain gorilla population using the Lincoln Index. Show your working.

Type answer here

Correct Answer: \frac{25\times24}{8}=75

Deg^°

Rad

Math Response

A population of emus was studied for five years. During that time there were 300 births and 120 deaths. 40 emus immigrated into the population and 20 emigrated out of it.

Calculate the population growth over this period. Show your working.

Type answer here

Correct Answer: \left(300+40\right)-\left(120+20\right)=200

Deg^°

Rad

Multiple Choice

In which months did the Cottontail Rabbits reach their carrying capacity?

• January and February

• March and May

• April and January

• April and May

Multiple Choice

What role do lichens play in the formation of soil on solid rock?

• They absorb water from the air.

• They provide shade for other plants to grow.

• They fix nitrogen from the atmosphere.

• They attract animals that bring nutrients.

Multiple Choice

What characteristic do early colonizer plants share?

• Small and water-dispersed

• Slow-growing and shade-tolerant

• Fast-growing and light-needing

• Large and animal-dispersed

Multiple Choice

What is a key feature of mature forests in the context of ecosystem succession?

• Absence of animal life

• Presence of slow-growing, shade-tolerant tree species

• Lack of soil development

• Dominated by wind-dispersed species

Multiple Choice

What is the main difference between primary and secondary ecological succession?

• Type of organisms involved
• Speed of the process
• Location where it occurs
• Presence or absence of soil

Multiple Choice

This is the ecosystem 137 years after a devastating forest fire, what type of community is this known as?

• Primary community
• Secondary community
• Climax community
• Pioneer community

Multiple Choice

Unproductive farmland is abandoned. What type of succession is shown going from figure A to figure B?

• Regenerative succession
• Primary succession
• Ecological succession

• Secondary succession

Multiple Choice

What was the original purpose of introducing cane toads to Australia?

• To control the population of native frogs

• To provide a new food source for native predators
• To control the cane beetle population
• To improve soil quality in agricultural areas

Multiple Choice

What was the outcome of introducing cane toads to Australia?

• They successfully controlled the beetle population.

• They adapted well without causing any ecological issues.

• They were quickly eradicated by native predators.

• They became a massive pest, failing to control beetles.

Multiple Choice

What makes the cane toad particularly dangerous to native Australian animals?

• Its size and aggressiveness.

• The toxic glands it possesses.

• Its speed and elusiveness.

• Its ability to reproduce quickly.

Multiple Choice

What challenge do conservationists face in controlling the cane toad population?

• Government restrictions.

• The vast number of cane toads.

• Lack of effective poisons.

• Lack of public support.

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