Ecology - AP Biology

An ectotherm relies on external sources to regulate its body temperature. Endotherms maintain a relatively constant body temperature, independent of their external environment. To regulate their body temperature, endotherms have a higher

Plants make up the bottom trophic level: the producers. This is because plants produce energy through photosynthesis. They do not have to eat other organisms to obtain energy, they make their own using carbon dioxide, water and sunlight.

Herbivores are plant-eating organisms. They are classified in the primary consumer trophic level. An easy way to remember this is to break down the word. Herbs are types of plants, so when we see “herb” in herbivore think of plants. Carnivores eat other animals. Autotrophs and producers need not eat anything to get energy, rather, they make their own.

The latin name consists of the genus and species of the organism. These are the most specific of the taxonomic classifications. The taxonomic classifications are domain, kingdom, phylum, class, order, family, genus, and species.

A community includes populations of different species. The study of a community looks at interactions between species, such as competition, symbiotic relationships, or predation.

Invasive species are organisms that become established outside their native range. In this example, the seed’s native range is the countryside. However, when it is carried by the wind to the forest (an environment outside its native range), it plants itself and establishes a population there. The seed is an example of an invasive species.

The population density is the measure of the population per unit area or volume, and may be measured over land or water.

The carrying capacity refers to the maximum number of organisms that can be sustained by the resources of an environment. The range of a population is simply the area over which the population can be found. Dispersion refers to the different regions where a species is found within a given area. Competition is the use of limited resources between multiple members of a population, or multiple species within a niche.

The earth's habitats and ecosystems are dispersed based on air circulation, rainfall, and topography. For example, when looking at the globe, we may notice that the world's major grasslands are always leeward of major mountain ranges, or that tropical rain forests are located around the equator. Why do grasslands fall on the leeward side of mountain ranges, and tropical rainforests at the equator? As the air travels up the mountain, it condenses and precipitation occurs. Once the air reaches the leeward side, it is dry, resulting in the grasslands and plains. Tropical rainforests are located at the equator, an area that gets constant sunlight and rainfall regardless of the earth's tilt. The dispersion of the earth's habitats and ecosystems is very dependent on such environmental factors.

A community is a group of populations of different species but live in the same area and interact. Community interactions may display interspecific interactions such as competition, predation, herbivory, symbiosis, or facilitation. A population is a group of organisms of the same species that live together and interact.

Competitive exclusion is when an inferior competitor is eliminated. In the moss example, the moss that is able to use resources more efficiently and reproduce quicker will beat out the less competitive moss. An ecological niche is the sum of a species’ use of the biotic and abiotic resources in its environment. Resource partitioning is the differentiation of niches that allows similar species to coexist in a community. If one of the mosses could adapt to use different resources, the two species could coexist together. Character displacement has to do with speciation. It refers to the tendency for character traits to diverge more in sympatric populations rather than allopatric populations.

Species diversity is the variety of organisms that make up a community. There are two parts of species diversity: species richness and relative abundance. Species richness refers to the number of different species in the community. In this example, forest 1 has greater species richness and diversity over forest 2.

The sea otter is an example of a keystone species. Keystone species are not abundant in the community, however they have a strong control on community structure because their ecological roles are so important. On the other hand, dominant species are those that are most abundant in their communities and have the highest biomass. The dominant species competitively exploits resources and avoid predation, giving them an advantage and allows them to grow large in number. Ecosystem engineers are species that dramatically alter their environment by changing its physical characteristics.

Ecosystems are described as a community of organisms and their interactions between themselves and the environment. Ecosystems include abiotic and biotic components of the environment and are not limited to one species.

Ecosystems are communities of abiotic and biotic components that interact together in the same environment. Ecosystems are controlled by both internal and external factors. Internal factors that control ecosystems include the availability of limiting resources, species presence, and disturbance.

Ecosystems are communities of abiotic and biotic components that interact together in the same environment. Ecosystems are controlled by both internal and external factors. External factors that impact ecosystems include but are not limited to the invasion of non-native species, climate, and time.

Despite their relatively small abundance, keystone species have a large impact on the environment in which they inhabit. If a keystone species is removed from an ecosystem, then there may be a large change in ecosystem’s stability.

Deforestation can be defined as the removal of forests by humans. Deforestation has many negative environmental impacts including soil erosion, a decline in biodiversity, and an increase in greenhouse gas emissions.

Tropical rainforest biomes have the greatest biodiversity of all biomes. They have only two seasons (rainy and dry) and the soil in these environments is generally nutrient-poor. Tropical rainforests also have a multi-layered canopy that allows little light to penetrate to the ground.

Primary succession is the colonizing of a new environment that lacks organisms and plant life. Primary succession is different from secondary succession; secondary succession is the colonizing of an environment that once supported life but was abandoned due to an ecological disturbance. An example of this is the colonizing of new land formed by lava flow.