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Chap 20 + Chap 21: Chapter 20 Population Ecology, Chapter 21 Community Ecology
Terms in this set (32)
The study of the interactions among organisms and between organisms and their nonliving environment.
A group of organisms of the same species living and interacting in a particular area.
Interacting populations of different species in a defined habitat.
All the living organisms in an area and the nonliving components of the environment with which they interact.
A pattern of growth that starts off fast and then levels off as the population reaches the carrying capacity of the environment.
The unrestricted growth of a population increasing at a constant growth rate.
The maximum population size that a given environment or habitat can support given its food supply and other natural resources.
Refers to the living components of an environment.
Refers to the nonliving components of an environment, such as temperature and precipitation.
Density dependent reduction factor
A factor whose influence on population size and growth depends on the number and crowding of individuals in the population (for example, predation). Density-dependent factors, such as the presence of predators, have different impacts on the population depending on the population size and crowding of individuals.
Density independent reduction factor
A factor that can influence population size and growth regardless of the numbers and crowding within a population (for example, weather). Density-independent factors, such as a severely cold winter, can affect a population of any size.
Choose an ecosystem in your town. What would classify as a population, community, and ecosystem?
Ecosystem: My home
Community: Humans, K9, Feline
Use infographic 20.5 to find examples of logistic growth and exponential growth
The rapid and unrestricted increase of a population growing at a constant rate is called exponential growth. When a population is growing exponentially, it increases by a certain fixed percentage every generation. As populations increase, various environmental factors such as food availability and access to habitat, the physical environment where an organism lives and to which it is adapted, limit an organism's ability to reproduce. When population-limiting factors slow the growth rate, the result is logistic growth, a pattern of growth that starts rapidly and then slows.
Are the examples listed in infographic 20.6 density dependent or independent reduction factors?
density dependent, if the wolf population goes down the moose population will go up and if the moose population goes up tree growth will slow. the number of one population depends on the number of other populations
Use the text and infographic 20.9 to explain how density dependent and independent reduction factors can interact to reduce population size.
Warm weather can bring on ticks and ticks weaken moose, when moose are weak it is easier for wolves to hunt them. this is an example of how independent reduction (warmer weather) bring on dependent reduction (ticks weakening moose and wolves eating more moose)
Ex. Warmer temperatures have affected moose in a more insidious way as well. About 10 years ago, Vucetich and his colleagues began to notice that a tick parasite was bothering the moose, and that warm weather seemed to favor ticks. Ticks suck the moose's blood and cause them to itch. The moose scratch themselves against trees and chew their hair out trying to rid themselves of the itchy freeloaders. Since a single moose may host many thousands of ticks, the combination of tick-related blood loss and heat-induced weight loss can be deadly
One topic this chapter is missing is competition. Do you think competition is a density dependent or independent reduction factor?Ch. 21, p. 501 describes competition.
Competition is a density-dependent limiting factor. The more individuals living in an area, the sooner they use up the available resources. Fewer resources means greater competition for those resources. Competition can be within one's own species.
Connect chapters 5&6 to chapter 20. How is carbon moving through the atmosphere and populations on the Isle Royale?
When an organism dies it releases carbon CO2 into the air this compiled with the natural carbon en0..
Species upon which other species depend and whose removal has a dramatic impact on the community.
A complex interconnection of feeding relationships in a community.
A linked series of feeding relationships in a community in which organisms further up the chain feed on ones below.
The feeding level of an organism, reflecting its position in a food chain.
Autotrophs (photosynthetic organisms) that obtain energy directly from the sun and form the base of every food chain.
Heterotrophs that eat other organisms lower on the food chain to obtain energy.
An organism that eats only plants
An organism (typically an animal) that eats animals.
An interaction between two organisms in which one organism (the predator) feeds on the other (the prey).
What is significant about keystone species?
You can think of a keystone species as analogous to the keystone in an archway—it doesn't support as much weight as the other stones, but if it is removed, the archway collapses. Similarly, keystone species play a crucial role in supporting a functioning community. While not necessarily—or even frequently—the most abundant members of a community, they exert an outsized influence because of their important ecological services. Loss of a keystone species from a community can spell disaster
Why do honeybee's fit into the category of keystone species?
Bees are keystone species because they play a fundamental role in supporting an entire community, much like the keystone in an arch.
Be able to classify species by trophic level
There can be several levels of consumers in a food chain. At the first level are herbivore animals that eat plants. At the second level of consumers are meat-eating carnivore, which eat the herbivores. Both herbivory and carnivory are forms of predation,an interaction in which one organism feeds on another. At the top of the food chain are those animals known as top consumers—animals such as coyotes, hawks, and wolves (as well as meat-eating humans), who have no natural predators and are not generally eaten by anything else in the community
How do the terms producer and consumer relate to trophic level?
producers—autotrophs such as plants and algae, which make their own food by obtaining energy directly from the sun. Producers are an extremely important part of any community because they supply energy to the rest of the food chain. Organisms higher up the food chain are consumers—heterotrophic organisms that eat the producers or eat other organisms lower on the chain to obtain energy.
What do the arrows represent in a food chain or web?
Energy flows in one direction through a food chain, from producers to consumers. As energy flows up the trophic levels in the food chain, most of it is lost to the environment, which explains why top consumers are rare in a community.
Why is energy lost as if flows through food webs?
When a mouse feeds on a blueberry bush, for example, most of the energy in the blueberries is either burned (in aerobic respiration) to fuel the mouse's activities and given off as heat, or passed through the mouse as indigestible plant fiber. Only a very small portion—about 10%—of the energy stored in the blueberries goes to putting weight on the mouse. The same is true for organisms, like birds, that eat the mouse that eat the blueberries—only about 10% of the energy in the mouse makes it into the body mass of the bird
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