population ecology Flashcards
population
- A group of animals of the same species living together in an
area
community
- A group of animals of the different species living together
in an area
ecosystem
A community of living organisms interacting with one
another and with the non-living components
immigration
- The movement of animals into a new area
emigration
The movement of animals out of an area
Mortality
The death rate or number of animals dying within a population
Natality
The birth rate or number of animals born in a population
. What is the effect of immigration, emigration, mortality and natality on
population size?
Natality and immigration INCREASES the population size
Mortality and emigration DECREASES the population size
- What are density dependent factors and briefly explain the effects of
these on population growth?
Factors that limit population growth based on the size of the population(resources available) (like
competition for food, water, oxygen, space/territory, shelter as well as number
of predators, parasites and occurrence of disease)
The larger the population, the more competition, more parasites, more disease
which all limit further population growth.
What are density independent factors and briefly explain the effects of
these on population growth.
Factors that affect population growth regardless of the size of the population
(natural disasters like floods, fires, earthquakes etc)
No matter how big or small a population, density independent factors will make
the population smaller.
What is the implication of environmental resistance and carrying capacity
for a species?
The population’s ability to successfully access resources.
- If resources are plentiful and population is small, the population grows
exponentially.
- As numbers increase, pressure on resources occurs – environmental
resistance occurs because the environment has reached its carrying
capacity.
What is the method of the mark- recapture method?
In a well-defined area:
Capture as many organisms as
possible, mark & release them.
Allow time for marked individuals to
mix with the rest of the population.
Recapture as many as possible.
Count the number of marked
individuals. Use a formula to
calculate the estimated population
size
precautions for the mark recapture method?
Allow little time between 1
st & 2nd
capture to limit births & deaths.
Repeat sampling several times &
calculate averages. Marking should
not affect individuals’ movement or
behaviour. No immigration and
emigration should occur
Method of the quadrat method?
Measure the size of the total
area. Randomly mark out
“frames” or quadrats of
known size within the total
area. Count the number of
individuals within each frame.
Use a formula to calculate
the estimated population size
precautions for the Quadrat method
Size and area of quadrats
must be known. Quadrats
must be randomly selected.
The exact number of
organisms in each quadrat
must be counted
Method of a census
Counting every
single individual in
a population
limitations for census
It is only suitable for
counting stationary
or sessile
organisms (like
plants or barnacles
on rocks), slow
moving animals
(like snails) or large
animals (like
elephants
Define predator prey relationship
The interaction that exists between animals that hunts for its food (predator)
and the animal that is being hunted (prey) through which the population size
of both the predators and the prey regulate the population size of the other.
What is the impact of food webs on populations?
prevents prey overpopulation by regulatingq population size
What is intra-specific competition
when organisms of the same species compete for the same resources at the same time
inter-specfic
when organisms of different species compete for the same resource at the same time
Explain one resource partioniong strategy among plants seen in a forest ecosystem
Spatial resource partioning occurs in a forest where plants grows to different heights in order to use different parts of the same resource which is light
What are resource partioning among animals
Temporal- same resource at different times (dirnal and nocturnal)
Spatial- same plant but different parts
What is meant by ecological succession
the process of change in different types of organisms present in an ecological community over time
