4.1 NOTES
•A ______is a group of organisms, all of the same species, that live in a specific area.
•Populations of organisms, do not experience ______growth. Rather, the graph of a growing population starts out slowly, then begins to resemble a ______curve.
•A J-shaped growth curve illustrates ______population growth. Exponential growth means that as a population gets larger, it also grows at a faster rate.
______, such as availability of food, disease, predators, or lack of space, will cause population growth to slow.
•Under these pressures, the population may stabilize in an ______growth curve.
•The number of organisms of one species that an environment can support indefinitely is its ______.When a population overshoots the carrying capacity, then limiting factors may come into effect.
•Biologists study the factor that determines population growth—an organism’s reproductive pattern, also called its ______
______life-history patterns are common among organisms from changeable or unpredictable environments. Rapid life-history organisms have a small body size, mature rapidly, reproduce early, and have a short life span.
•Large species that live in more stable environments usually have ______life-history patterns. Slow life-history organisms reproduce and mature slowly, and are long-lived. They maintain population sizes at or near carrying capacity.
Density factors and population growth
Three ______of dispersal are random, clumped, and uniform.
Ecologists have identified two kinds of limiting factors that are related to dispersal: ______and ______factors. Population density describes the number of individuals in a given area.
Density-dependent factors include ______, competition, predators, parasites, and food.
Disease, for example, can spread more quickly in a population with members that live close together.
Density-independent factors can affect ______populations, regardless of their density.
Most density-independent factors are ______factors, such as temperature, storms, floods, drought, and major habitat disruption.
When a ______consumes prey on a large enough scale, it can have a drastic effect on the size of the prey population.
______is a density-dependent factor.
•When a population increases to the point at which demand for resources exceeds the supply, the population size ______
•When populations of certain organisms become crowded, individuals may exhibit symptoms of ______.
As populations increase in size in environments that cannot support increased numbers, individual animals can exhibit a variety of stress symptoms.
•These include ______, decrease in parental care, decreased fertility, and decreased resistance to disease. They become limiting factors for growth and keep populations below carrying capacity.
5.1 NOTES
______refers to the variety of species in a specific area.
•The simplest and most common measure of biodiversity is the number of ______species that live in a certain area.
______increases as you move toward the equator.
The richest environments for biodiversity all seem to be ______places: tropical rain forests, coral reefs, and large tropical lakes.
Living things are ______. •Living things can be ______for other living things.
Scientists do know that if a species is ______from an ecosystem, the loss may have consequences for other living things in the area.
______can bring stability to an ecosystem.
Another important reason for maintaining ______is that it can be used to improve people’s health.
______is the disappearance of a species when the last of its members dies.
There is also a certain level of natural extinction, called ______extinction, that goes on.
Scientists estimate that background extinction accounts for the loss of one to ______per year. However, the current rate of extinction exceeds that by many times.
A species is considered to be an ______when its numbers become so low that extinction is possible.
When the population of a species is likely to become endangered, it is said to be a ______species.
One of the biggest reasons for decline in biodiversity is ______loss.
Habitat ______is the separation of wilderness areas from other wilderness areas.
Habitat fragmentation has been found to contribute to:
increased extinction of local species,
changes in overall biodiversity,
disruption of ecological processes,
new opportunities for invasions by unwanted or exotic species,
increased risk of fire.
The smaller the fragment, the ______biodiversity the area can support.
Geographic isolation can lead to genetic ______.
The edge of a habitat or ecosystem is where one habitat or ecosystem meets anoth er.
The different conditions along the boundaries of an ecosystem are called ______.
Another threat to biodiversity is habitat ______, the damage to a habitat by pollution.
Three types of pollution are air, water, and land pollution.
Burning ______is also a major source of air pollutants such as sulfur dioxide.
Acid precipitation—rain, snow, sleet, and fog with low pH values—has been linked to the deterioration of some forests and lakes.
The ______in this region—known as the ozone layer—absorbs some of the ultraviolet waves striking the atmosphere, reducing the ultraviolet radiation reaching Earth’s surface.
Water pollution degrades aquatic habitats in streams, rivers, lakes, and oceans.
Excess fertilizers and animal wastes are often carried by rain into streams and lakes.
The sudden availability of nutrients causes ______, the excessive growth of algae.
Exotic species- People sometimes introduce a new species into an ecosystem, either intentionally or unintentionally. These species can cause problems for the ______species. When exotic species are introduced, these species can grow at an ______rate due to the fact that they are not immediately as vulnerable to local competitors or predators as are the established native species.
5.2 NOTES
______biology is the study and implementation of methods to protect biodiversity. Natural resources include sunlight, water, air, and plant and animal resources.
In response to concern about species extinction, the ______became law in 1973. This law made it illegal to harm any species on the endangered or threatened species lists.
A ______is the physical location where an organism lives and interacts with its environment. Establishing parks and other protected regions has been an effective way to preserve ecosystems and the communities of species that live in them.
A general strategy for protecting the biodiversity of an area probably is to protect the largest area possible. Therefore, another strategy for preserving biodiversity is to connect protected areas with ______. • Habitat corridors are protected strips of land that allow the migration of organisms from one wilderness area to another.
The philosophy of ______strives to enable people to use natural resources in ways that will benefit them and maintain the ecosystem.
______programs release organisms into an area where the species once lived.
An organism that is held by people is said to be in captivity.
By establishing seed banks for threatened and endangered plants, the species can be reintroduced if they become extinct
• Animals kept in ______may lose the necessary behaviors to survive and reproduce in the wild.