Chapter 24 Populations Flashcards
What is a limiting factor in regards to population?
An environmental resource or constraint that limits population growth
What are the stages of population growth and what happens during these stages?
1) Slow growth- only a few members, births>deaths, increase in size, also called lag phase
2) Rapid Growth- high amounts of breeding, exponential growth, no limits births»>deaths, also called log phase
3) Stable- with fluctuations, growth limited by external factors, carrying capacity
What factors affect birth rate?
Economic Conditions
Culture
Social Pressures
Access to Contraception
Politics
What factors affect death rate?
Age profile
Life expectancy
Food
Sanitations
Clean water access
Disease
Medical availability
War
Economics
What are the limiting factors of population growth that plants are more affected by?
Availability of nutrients, water, and gases
Competition
Accumulation of waste
Disease
Predators
Describe the changes in population and why when an algae appears in a pond for the first time
Favourable conditions e.g nutrients, water and gas availability, exponential growth
Nutrients are used up, light cannot access lower levels, other species
Accumulation of waste products
Carrying capacity is reached, further growth cannot exist
Define carrying capacity
The maximum population size than can be maintained in a particular habitat
What are the two types of population growths? How do they work?
K- slowly approach carrying capacity, slow reproductions, long life span - e.g humans
R- Exceed carrying capacity then fall as resources not enough to sustain, Quick reproduction and short life spans- insects
What are density independent factors, and an example?
Factors which effect a population regardless of size
e.g earthquakes, fires
What is competition and the two types?
When two or more organisms compete for the same resources
Intraspecific- Same species
Interspecific- Different species
What is the competitive exclusion principle?
When resources are low, if two species compete and are equally adapted, two small populations form
If one species is better adapted, it will outcompete the other, until the other eventually dies out if no change occurs
What are the main stages on a graph showing intraspecific competition?
(X-time, Y- n. of organisms)
1) Growth, resources plentiful, births>deaths
2) Fall in population size, resources become limited, not enough for all, deaths>births. Only most well adapted survive- links to natural selection
3) Less competition for resources as population smaller, allows growth
Repeat
What is an ecological niche?
The habitat an organism lives in and its role within that habitat
Two species cannot occupy the same niche
What are the main stages of a predator prey graph?
1) Prey population increases. More food available for predators, numbers begin to increase after a short time
2) As there are more predators, more prey are eaten, population decreases, to below predators
3) Less prey, more intraspecific competition between predators so population decreases.
4) Less predators mean more prey can survive, increase in prey population.
Repeats. In reality not as simple as food webs, abiotic factors…
How does competition lead to natural selection?
When there are times of heightened competition, only the most well adapted survive, the most successful
Overtime and generations, these successful characteristics can change a species
