Biology- 4.1

Describe 2 reasons why a species might not be able to expand its range.

A change in temperature or even predators can stop a species from expanding its range.

What are S-shaped growth curves are also known as?

A logistic growth model curves into the form of an S.

Describe what can limit population ranges within ecosystems, biomes or biospheres. Provide examples of both biotic and abiotic factors that can limit population ranges.

A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded regions. A change in temperature range, humidity level, annual rainfall or sunlight might make a new geographic area uninhabitable for the species. Biotic factors like predators, competitors, and parasites also are threats that affect the population range.

When considering exponential growth rate, explain in detail why after a long lag phase the population begins to grow so rapidly.

After the long lag phase population begins to grow rapidly because the total number of organisms that are able to reproduce has increased.

Density- dependent factor

Any factor in the environment that depends on the number of members in a population per unit area.

What types of factors are usually considered density dependent? Provide at least 3 examples.

Any factor in the environment that depends on the number of members in a population per unit area. Examples are predators, disease, parasites and competition.

Density- independent factor:

Any factor in the environment that does not depend on the number of members in a population per unit area.

Understand the concepts of carrying capacity and limiting factors.

Carry capacity is the maximum number of individuals in a species that an environment can support for the long term. Carrying capacity is limited by limiting factors such as energy, water, oxygen, and nutrients. The concept of carrying capacity is used to explain why many populations tend to stabilize.

What is carrying capacity limited by?

Carrying capacity is limited by the energy, water, oxygen, and nutrients available.

Explain in detail why competition is considered a density dependant factor.

Competition increases when density increases. When resources like food, space, and water become limited individuals in a population compete for the resources. It can occur within a species or between different species.

Discuss the population changes in regards to the increase and decrease in food supply as a limiting factor.

Decreasing the available amount of food can change the number of individuals that are able to survive in a given area. More food, larger population. Less food, smaller population.

Explain the difference between Density and Independent and Density Dependent Factors.

Density independent factors are factors that don't depended on other things, things like weather, drought, flooding, or hurricanes. Density dependent factors are that depend on other organisms, or populations. An example would be, disease, predation, and competition.

Explain in detail why disease is considered a density dependant factor.

Disease is considered a density dependent factor because it occurs when population size increases and when population density is high. Disease is transmitted easily from one individual to another because of frequent contact.

What type of curve represents exponential growth?

Exponential growth looks like a "J" curve.

Population:

The members of a single species that share the same geographic location at the same time

Compare and contrast crown fires and ground fires : Discuses the ecological impacts of both. Relate your answers in terms related to the specific type of limiting factors.

Extreme heat from a crown fire, which is a fire that advances to the tops of the trees, can destroy many mature tress. Smaller, more frequent fires such as a ground fire has the opposite effect of the population. The ground fire thins out growing plants that use nutrients so the tress can become healthier. This is an independent limiting factor

Provide specific examples of populations that would most likely exhibit logistical growth.

Humans, elephants, and blue whales

List examples of K-strategist:

Humans, elephants, blue whales

What are populations? Provide at least one example.

The members of a single species that share the same geographic location at the same time is a population. An example of a population would be the amount of catfish in the TN river.

Provide specific examples of populations that would most likely exhibit exponential growth.

Insects and bacteria could exhibit exponential growth.

How do we know that resources being utilized exponentially in the lag phase?

It is important to recognize that even in the lag phase, the use of available resources is exponential. This causes resources to become limited and population growth rate slows

How are populations of K-strategist usually controlled?

K-strategy populations are usually controlled by density dependent factors.

What will eventually slow exponential growth? Provide some examples

Lack of resources will eventually slow exponential growth, once a certain level has been reached, organisms will begin competing.

Which is more important when we are looking for changes in populations: natality/fatality or immigration/emigration? Explain why.

Natality and fatality are more important in determining the population growth rate, because immigration and emigration rates are equal.

Explain in detail why parasites are considered a density dependant factor.

Parasites negatively affect population growth at higher densities.

Provide an example of how you think density can be calculated.

Population can be calculated in sq. feet, or by miles. Actually, whatever unit works best for the area.

Describe the ways in which populations are distributed.

Populations are distributed through dispersion. Organisms can be dispersed into uniform groups, clumped groups, and even random groups. A primary factor in the pattern of dispersion for all organisms is the availability of resources such as food.

Explain how populations can be limited by human activities (anthropogenic) . Provide some specific examples.

Populations can be limited by the unintended results of human altercations of landscapes. One example would be that over the last 100 years, human activities on the Colorado River, such as building dams and water diversions, have reduced the water flow and changed the waters temperature. Air, land, and water pollution come from humans.

How are populations of organisms described? Explain what is meant by each.

Populations density describes how many individual organisms live in a given area. Dispersion describes how the individuals are spaced within that area. Population range describes a specie's distribution.

Why does an S-shape growth curve levels off?

The S- Shape graph curves off when an ecosystem or population has reached it's carrying capacity.

How do emigration and immigration impact population growth respectively?

The emigration is the number of individuals moving away from a population. The immigration the number of individuals moving into a population.

Carrying capacity:

The maximum number of individuals in a species that an environment can support for the long term.

What is natality and fatality? How do each it impact growth rates?

The natality of a population is the birthrate in a given time period. The fatality of a population is the death rate in a given time period. A population stops increasing when the number of births is less than the number of deaths or when emigration exceeds immigration.

Population density

The number of organisms per unit area.

Dispersion

The pattern of spacing of a population.

What is a likely explanation that could explain why small fish are often found in clumped (schools) distributions?

The school of fish is considered a clumped group because they stay together so that they can work together and defend each other.

What are the two categories of limiting factors for populations?

The two categories are density- independent factors and density- dependent factors.

What types of factors are usually considered density independent? Provide at least 3 examples.

These factors are usually abiotic and include natural phenomena such as weather events. Examples are flooding, drought, and hurricanes.

Population growth rate:

This explains how fast a given population grows.

List the specific characteristics of r-strategist (rate strategy):

This is an adaptation for living in an environment where fluctuation in biotic or abiotic factors occur. They are typically small organisms, that have a short life span, and live in harsh environments, they are able to produce many offspring. Also, they are able to reproduce VERY early in their life cycle. They mostly exhibit exponential growth rate habits.

List the specific characteristics of K-strategist (carrying capacity strategist)

This is an adaptation for living in stable environments. They are generally larger organisms, with a long life span. They produce few offspring. They provide great parental care. They probably show the S curve, or logistic growth rate.

Emigration

This is the number of individuals moving away from a population.

Immigration

This is the number of individuals moving into a population.

Describe the 3 types of dispersions in populations and provide examples of organisms that exhibit these traits.

Uniformed dispersion is when organisms are dispersed evenly so that there is less competition. Example: Black bears are very territorial. Clumped dispersion is when organisms are clumped up so that they can work together, and depend on each other. Example: Bison are in packs, and generally settle where resources are. Random Dispersion is when organisms are randomly placed because they are independent, and want to be alone. They are "generalist" because they have a very broad niche in ecosystems. Example: Deer can be dispersed anywhere because they eat more than one thing.

What typically occurs when populations reach carrying capacity?

When carrying capacity is reached species begin competing for the resources, and many organisms die.

List examples of r-strategist:

insects and bacteria

Describe characteristic of populations.

population density, spatial distribution and growth rate.