Chapter 19+ 20 Flashcards
Population
All the individuals of the same species living in the same area
Ex: squirrels on campus
Difference between population density and species richness ?
Density is number of individuals per unit area
Richness is the number of species living in a particular area
Random distribution
Individuals show no apparent pattern in their distribution
Ex: dandelions
Clumped distribution
Individuals are patchy or in groups
Ex: school of fish
Uniform distribution
Individuals are evenly distributed throughout an area
Exponential growth
As the population gets bigger, growth rate increases
Rapid growth in populations where resources are unlimited
J-shaped graph
Logistic growth
Once resources become limited, population growth slows down
Population size reaches carrying capacity
S-shape graph
Identify as density-dependent tacit or a density-independent factor
a) drought
b) disease
c) Forest fire
d) food
A) density independent
B) density dependent
C) density indecent
D) density dependent
Intraspecific competition
Competition between members of same species
Inter specific competition
Competition between members of different species
Can result in competitive exclusion
Ecological niche
An organism’s role in the community
Its relationship with everything (living and non living )
Every species in an ecosystem has one
Predation
When one animal hunts and eats another animal (prey)
Herbivory
Eats producers (plants)
Foundation species
Important for the structure of the community
Modify the environment and make it habitable
Often abundant
Often producers (photosynthetic)
Ex: trees, coral reefs
Keystone species
A species that helps to stabilize and maintain other species in an ecosystem
Ex: wolf, sea otter
Producer
Autotroph
Produce their own food
Carry out photosynthesis
Primary consumer (herbivore)
Eats producers
Secondary consumer (omnivore or carnivore)
Omnivore: eats animals and producers
Tertiary consumer (top carnivores)
Eats animals
What direction to the arrows point in a food web: towards the source of the energy or towards the consumer ?
Towards the consumer
Ecology
Study of interactions between organisms and their environment
Population distribution
The distribution of individuals within a habitat st a given point in time
Human population growth rate in early human history ? During the last 200 years? 20 years ?
Rate was low
200 years: rate was 0.1% per year
Current growth rate: 1.1% per year
What are the environmental impacts of human population growth?
We need more:
Food( and land for agricultural and grazing) Water Energy Raw materials Space
Carrying capacity
The maximum number of individuals that can be supported indefinitely in a given environment
Density - dependent factors
Factors that increase effects as population size and density increases
Limits population growth by:
Limited food supply
Increased risk of diseases
Increases in waste levels
Cause:
Decrease in birth rates and increases death rates
Density- independent factors
Population limiting factors that occur regardless of population size
Ex: natural disasters, pollution, droughts
Consumption ?
resources being use
Waste produced ( pollution )
Scenarios if population surpasses the carrying capacity ?
Population crash
Population cycle : repeated crashes and rebounds
Age structure diagrams
A summary of the numbers of individuals in different age groups
Can be used to predict a populations future growth
Age diagrams (pyramid with large base)?
The majority of the population is young and that the population is still growing
Age diagram (narrow base)
Decrease in population growth
Developed counties with greater % of middle aged and older individuals
Age diagram (column)
Slow growth
Fewer young and reproductive aged individuals and a greater proportion of older individuals
Female literacy occurs more in bigger populations
True or false
True
More income per capita (country) means a bigger population
True or false
True
