Chapter 5 and 6 Flashcards
- What is a population?
A group of interbreeding individuals of the same species.
- Why are most populations clumped? Explain.
First of all, resources tend to be clumped so that causes the species to clump in the same areas. Secondly, species would have a bigger chance of finding resources if they were in a group rather than alone. Third, they can help protect each other. And lastly, being in packs gives predator species a larger chance of getting a meal.
- Give an actual example for each of pattern of population distribution.
Clumped – elephants gather together to find water
Uniform – Creosote bushes grow in a uniform pattern to effectively utilize water availability
Random – dandelions are weeds that grow wherever
- What is the formula for population change?
(Births + immigration) – (Deaths + emigration)
- What is a population’s age structure?
Its distribution of individuals among various age groups; Can have a strong effect on how fast a population grows.
- Define “range of tolerance”.
Each population in an ecosystem has a range of tolerance to variations in its physical and chemical environment.
What is the limiting factor principle?
Too much or too little of any physical or chemical factor can limit or prevent growth of a population, even is all factors are at or near optimal range of tolerance.
- What prevents a population from growing indefinitely?
Because there is a limitation on resources and competition with other populations
Define the term “Environmental resistance” and give an example.
This is the combination of all factors that act to limit the growth of a population. For example, Sea Otters face risk because they reproduce slowly, there is an increase in their predators, popular bacteria has been killing them and they are also killed by chemicals dumped in the water like PCBs and oil.
- Explain why sea otters are considered indicator species.
They are indicator species because when chemicals being dumped in coastal waters effect their population, it reflects the state of the environment in those areas.
- Discuss three ways changes in human behavior could help sea otter populations to recover.
Reduce oil spills, reduce input of harmful chemicals into the ocean or at least on the shore and stop the input of harmful parasites from cat litter.
- Why are sea otters considered keystone species? Explain.
These are species whose population change effects the population of other species. For example, when the Sea Otter’s population is effected, there is also a decline is sea kelp which then affects the biodiversity of the kelp forest and the energy flow in that ecosystem.
- When might a population experience a “die back”?
These are also known as a population crash where a species exceeds their carrying capacity and then their resources run out causes them to die out very quickly.
- Explain why a population that exceeds its carrying capacity can have the long-term effect of reducing the area’s carrying capacity. Include at least one example.
Well when a population exceeds it carrying capacity, it severely affects the environment around it so when this happens the capacity can change drastically.
- What animal kills more humans than any other? What, if anything, should be done to control this animal’s population?
White-tailed deer kill more people in car accidents in the United States than any other animal. Many ideas have been proposed to control this animal’s population such as birth control, long term and short term, but many of these propositions are very expensive.
- Compare/Contrast density-dependent with density-independent factors.
Dependent – parasitism, infectious diseases, and competition for resources. These have a greater effect as population density increases.
- Describe stable, irruptive, cyclic and irregular patterns of population variation and give examples of each.
Stable – Population fluctuates above and below the carrying capacity. Like species found in tropical rainforests where climates are very consistent. Irruptive – Populations that reach a high peak and then crash down. Short lived and rapidly producing organisms are characteristic of this trend.
Cyclic – Populations who rise for a long period of time and then decline for a long period of time. For example, the lynx and the snowshoe hare so this because of resources.
Irregular – No recurring pattern in population. Species in areas of inconsistent weather patterns.
- Give 2 historic examples of die-back in human populations.
Ireland faced on these when their potato crop was destroyed; about 1 million people died. In the 14th century, the bubonic plague killed at least 25 million people.
- Describe the processes of primary and secondary succession. Give an example of each.
Primary – Gradual establishment of biotic communities in lifeless areas where there is no soil in a terrestrial ecosystem. For example, bare rock that is exposed by a glacier is primary succession.
Secondary – Where a series of communities or ecosystems with different species develop in places containing soil. Begins in an area where the ecosystem has been disturbed. For example, abandoned farmlands or burnt forests are secondary successions.
- How has the view of scientists recently changed concerning ecological succession?
One thing that ecologists have picked up on is the ability for one species’ growth to enhance the growth of another species. Also plants or animals limit the growth of other species such as plants that release toxic chemicals around them.
Compare/Contrast persistence and resilience.
Persistence is the ability for an ecosystem to survive constant disturbances without dying out but resilience is the ability for an ecosystem to revive or come back to life after is has died out or failed to have enough persistence.
Use the second Law of Thermodynamics to help explain why predators are generally less abundant than their prey.
Since energy is always transferred into lower quality energy then when predators eat their prey they get less energy then they are actually eating.
Explain why most species with a high capacity for population growth (bacteria, flies) tend to have small individuals, while those with low capacity for population growth (humans, elephants) tend to have large individuals.
Since larger animals take up more space and therefore have a more dense population, there is more competition for life causing more deaths and a low capacity population growth.
List three factors that have limited human population growth in the past that we have overcome. Describe how we overcame each of these factors. List two factors that may limit human population growth in the future. Are we close to reaching those limits?
AIDS has limited human population especially for a specific time but now we have treatment for it, which drastically reduces the amount of deaths. Before we expaned to other countries, most people were stuck on one continent battling for land and killing each other. This connects directly to natural resources, which we have found to be lacking at some points so we expand to other countries to find abundant amounts of natural resources. Many of these limits we will still face in the future and we are very close because eventually we will have no where else to find more resources which will be the end of us.
