Honors Biology Notes Grade 10 Highschool Unit 9 Ecology Part 2:

Academic Work Part 2: Population Ecology & Biodiversity

Define

Population Density: # of individuals/unit of area Growth Rate: the rate at which a population increases in size
Growth Rate: the rate at which a population increases in size
- Positive = population is growing
- Negative = population is shrinking
Birth Rate: the ratio between the number of live-born births in the year and the average total population of that year.
Death Rate: the number of deaths due to a disease divided by the total population.
Immigration: an animal makes its home in a habitat because it can make use of the resources there or because it is a good fit for them.
Emigration: an animal leaves its home because it has to locate a new habitat that is more suited to its needs.

Compare and contrast: exponential growth vs. logistic growth

Exponential growth is when a population grows at an accelerating rate, while logistic growth is when the growth rate slows down as the population reaches its carrying capacity.

What is carrying capacity?

Define:

Limiting Factor: keep populations from growing at exponential rates by
- Decreasing births and immigration
- Increasing deaths, emigration
Density Dependent: impact populations once the population has reached a certain density/size
Density Independent: Impact populations regardless of size/density

Compare and contrast: density-dependent vs. density-independent limiting factors

Density-dependent limiting factors are factors that affect a population based on its size, while density-independent limiting factors are factors that affect a population regardless of its size.

Explain why invasive species can be so destructive to the native species community

Disturb an ecological community's balance
Often dominate the local species, which has a significant negative impact on the surrounding area.
Can result in changes to biodiversity
- 4 real-world examples
- 1. Asian Longhorned Beetle: This invasive insect has caused significant damage to trees in Massachusetts, particularly maple trees.
- 2. Zebra Mussel: This invasive shellfish can outcompete native shellfish for food and habitat, leading to a decline in native populations.
- 3. Japanese Knotweed: This invasive plant causes damage to building structures and substructures by targeting weak points, such as cracks in the walls, and attempting to grow through them.
- 4. Purple Loosestrife: This invasive plant displaces and replaces native flora and fauna, eliminating food, nesting, and shelter for wildlife.

Predict what would happen to the community below if an invasive primary consumer with no predators were introduced to the food

The balance between organisms would be upset by the invading species eating the creatures at the top of the food chain. The invading species would eat a lot of food, which may cause the population of other consumers to fall. The numbers of secondary and tertiary consumers may also fall as a result of this, which would have an impact on the rest of the food chain. Also, the invasive species could outcompete native species for resources, resulting in a loss of biodiversity.

Describe 2 examples of keystone species

Sea Stars:
- Predate on mussels
- Removal or reduction in sea stars leads to an increased birth rate of mussels
- Biodiversity is reduced and the ecosystem collapses
Beavers:
- Create ponds by damming rivers
- The pond offers the beaver a place to build a lodge safely away from predators
- Beaver ponds also create habitat for other species:

Explain how a keystone species is different from an indicator species.

A keystone species has a large impact on the structure and function of an ecosystem relative to its abundance, while an indicator species is used to monitor the health of an ecosystem.