Ecology - Chapter 2
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Definition: All of the individuals of one species that live in the same place at the same time.
Example: The current Asian Elephant population of Asia consists of all of the Asian Elephants currently living in Asia.
- Populations tend to increase when individuals reproduce at higher rates than what's needed to replace individuals that have left the area or died.
- Exponential growth of a population occurs under certain conditions, and for a short period of time (in nature) (see Exponential Growth for more details)
- Once a population reaches it's carrying capacity, the size of the population will be at a balance, or equilibrium (see Carrying capacity for more details)
Definition: Growth that creates a J-shaped when population is graphed against time
Example: When a treaty designed to conserve wildlife was signed in 1911, the northern fur seal population underwent exponential growth. See diagram below.
- Exponential growth occurs under certain conditions (such as introduction to a new habitat), and for a short period of time (in nature)
- There are usually three parts of the J-shaped curve: lag phase (when the population begins to increase), exponential growth (population growth), and carrying capacity (when population is at equilibrium, see Carrying capacity for more details)
- Limiting factors limit the growth and amount of a population (see Limiting factors for more details)
Definition: Factors that limit the growth of a population in an ecosystem
Example: For organisms to survive, they need water, oxygen, nutrients and other resources. However, ecosystems contain finite amounts of resources, meaning that the number of organisms in an ecosystem are limited by the amount resources in said ecosystem.
- Limiting factors affect the carrying capacity of a population
- Resource needs, abiotic factors, and biotic factors can all be limiting factors
Definition: The size of a population that can be supported for an unlimited amount of time by the services and resources of an ecosystem
Example: As said in the Limiting Factors flashcard, there are a limited amount of resources in an ecosystem. The carrying capacity of a population is the size of said population that can be supported by these limited resources for an unlimited time.
- When a population is maintained at its carrying capacity, the size of the population is at an equilibrium
- When a resource is depleted at a rate that exceeds the carrying capacity of an ecosystem, the population will drop to an equilibrium.
- Because humans alter natural ecosystems to suit their own needs, the carrying capacities of these ecosystems change. Often, it decreases.
- The intellectual abilities of humans have allowed them to produce huge improvements in health, education, agriculture, medicine, and technology. These improvements have allowed human carrying capacity to greatly increase.
- See Exponential growth for a diagram with carrying capacity
Definition: The place of an organism in an ecosystem; the way an organism occupies a position in an ecosystem
Example: The brown bat's ecological niche consists of the resources it uses (eg. insects it eats), the abiotic limiting factors affecting it (eg. tolerable temperature range), and it's biotic relationship with other organisms (eg. competition with nighthawk for insects).
- Different species also provide multiple different services for their ecosystems by occupying their niches
- No two species can occupy the exact same ecological niche
- Different ecosystems have many, many different niches
Definition: An organism that captures and consumes other organisms
Example: A crocodile (predator) consuming a wildebeest. See image below.
- Predators and prey influence each other, especially each other's population size
- There are two types of predator-prey interactions that can influence population size: Bottom-up population regulation and Top-down population regulation.
- Bottom-up population regulation occurs when a shortage of a plant resource at the bottom of the food chain causes declines in organisms at the higher trophic levels
- Top-down population regulation occurs when prey numbers increase, which causes predator numbers to increase, which, in turn, causes prey numbers to decrease, which causes predator numbers to decrease. This cycle repeats itself.
Definition: An organism that is consumed by a predator
Example: A wildebeest (prey) being consumed by a crocodile.
See Predator for more information
Definition: A symbiotic relationship between two species where both of the species receive benefits
Example: Coral and algae are in a mutualistic relationship, where algae provide the coral with up to 90% of the coral's energy requirements, while coral provide the algae with protection, nutrients, and carbon dioxide for photosynthesis.
For some species, such as coral, their symbiotic partner is an essential biotic factor
Definition: An organism with a niche that is dependent on association with a host organism
Example: The brainworm, a parasite, is dependent on the white-tailed deer, it's host, for laying it's eggs in it's brain.
- Most parasites harm their hosts (with the exception of the brainworm and the white-tailed deer)
- Although the white-tailed deer is generally unharmed by the brainworm, other members of the deer family are very vulnerable
Definition: A biotic interaction that occurs when multiple organisms compete for the same resource, at the same place and time.
Example: The brown bat and common nighthawk both compete for insects.
- Competition can limit the size of a population, and can influence the ecological niche of an organism
- The more energy an organism spends competing, the less energy it has for growth and reproducing
- When there is no competition, species can occupy a broad niche. When there is competition, species must occupy a narrower niche.
Definition: The use of a resource sustainably; use of a resource that does not cause long-term depletion of said resource, or affect the diversity of the ecosystem where the resource comes from
Example: Humans cut down trees. For sustainable use of trees, humans must cut down a minimal amount of trees, so that it does not lead to long-term depletion of trees, or affect the diversity of the ecosystem the trees come from.
- In order to continue to occupy a broad niche, we must use use of resources sustainably
- If humans do not use resources in a sustainable way, our niche may shrink over time
Definition: the amount of time needed for a population to double in size
Example: Currently, the doubling time of the human population is 60 years, meaning it takes the human population 60 years to double.
- 400 years ago, the doubling time for humans was 650 years
- In the early 1800s the human population had a doubling time of 200 years
- The reason for the major decrease of doubling time were the beginning of the industrial revolution and scientific advances that occured between the 1800s and 2000s
Definition: a measure of the impact an individual or population has on the environment, specifically energy consumption, land use, and waste production
Example: The average person in a developed country has a large ecological footprint, because each person uses up lots of energy and land, and produces lots of waste.
- The larger the ecological footprint, the higher the negative impact an individual or population has on the environment
- Developed countries have larger ecological footprints
- Large ecological footprints in a world with limited resources and is dependent on non-renewable fossil fuels are likely to be unsustainable (see Unsustainable for more details)
- Individuals can reduce their ecological footprint by consuming fewer resources, or using existing resources more efficiently
Definition: Opposite of sustainable; used to describe a pattern of activity that leads to a decline in the function of a given ecosystem
Example: As stated in the Ecological footprint flashcard, large ecological footprints in a world with limited resources and is dependent on non-renewable fossil fuels are likely to be unsustainable.
Definition: Use of resources at levels that can continue for an infinite amount of time
Example: Humans cut down trees. For sustainable use of trees, humans must cut down a minimal amount of trees, so that we can continue to use the same levels of trees forever. (also see Sustainable use)
Definition: Benefits provided by sustainable ecosystems and are experienced by organisms (including humans)
Example: Trees help reduce temperatures and form rain clouds; over half of the moisture above tropical forests comes from trees. Because trees extract large amounts of water from soil, on hot days, this water escapes through stomata in the tree's leaves, adding water vapor to the atmosphere.
- Ecosystem services are the natural result of all the activities that happen in the biosphere
- Ecosystem services allow ecosystems to function, which is a requirement of sustainability.
- Many organisms, including trees, insects, and birds, provide ecosystem services
Definition: The change of a land that was originally not a desert into a desert
Example: As explained in the Ecosystem services flashcard, trees help reduce temperatures and form rain clouds. When large amounts of trees are cut down, the climate can become hotter and drier, and possibly leading to desertification of the area the trees came from.
- Desertification may result from climate change and unsustainable farming
- Areas in Ontario have suffered from desertification in the past, from logging
Definition: A nature-based, sustainable form of tourism that involves recreational activities provided by sustainable ecosystems
Example: Many people get recreational enjoyment from kayaking, hiking, and fishing, which are all activities that are provided by sustainable ecosystems.
- Ecotourism is a multi-billion dollar worldwide industry
- Tourists to Canada can get enjoyment from Canadian ecotourism too
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