6.3.2 Populations and Sustainability Flashcards
(92 cards)
Draw, label and annotate with explanations, a generalised growth curve for natural populations
*diagram on flashcard
- lag phase - slow growth - small number of individuals
* low reproductive rate
* death rate low. birth rate > death rate
* nutrient level high - log (exponential) phase - rapid growth - number of
breeding individuals increases
* population size multiplies exponentially
* high reproductive rate
* death rate low birth rate»_space; death rate
* nutrient level high - stationary phase - stable state - population growth
prevented by external constraints
* birth rate = death rate
* nutrient level low - death phase - reproductive rate low
* death rate high
* nutrient level very low
Define abiotic factor
the non-living conditions in a habitat
Define biotic factor
the living components of an ecosystem
Define limiting factor
the factor which limits the rate of a process
Define carrying capacity
the maximum population size that an environment can support
What are (3) examples of (abiotic+biotic) limiting factors for population size and explain how they affect population size?
abiotic: temperature, pH, light intensity, water availability, oxygen concentration, humidity
biotic: predation, food supply, grazing, paratism, disease, intraspecific and interspecific competition
Define density dependant factors and give 3 examples
factors whos strength depends on the population size
e.g. competition, predation, grazing, disease
Define density independant factors and give 3 examples
factors that will affect the same percentage of the population regardless of its size
e.g. natural disasters, temperature
Define migration
the movement of individuals from one place to another
Define immigration
the movement of individuals into a particular area
increases population size
Define emigration
the movement of individuals out of a particular area
decreases population size
Define intraspecific competition
competition between organisms of the same species
Define interspecific competition
competition between organisms of different species
4 examples of what organisms might compete for?
*space
*food
*light
*water
Describe and Explain the competitive exclusion principle
Competitive exclusion principle -
where 2 species are competing for same limited resources
the one that uses resources more effectively will ultimately eliminate the other/ the two species cannot coexist
Why intraspecific competition an example of a density dependent biotic factor and why can it result in population fluctutations over time?
intraspecific competition occurs when members of the same species compete for the same resources.(biotic)
-greater availability of resource all organisms survive and reproduce
- reproduce = higher population size
- resources limited now as more sharing of food and space
-> population decreases
now less competition in smaller population = pop growth
Define predator
an animal that naturally preys on others
captures and feeds on other animals
Define predation
the capturing of prey in order to sustain life
Explain the general pattern shown in predator-prey relationships?
stage 1 -
*increase in prey population provides more food for predators - *more can survive and reproduce = increase in predator population
stage 2 -
*increase predator population eats more prey organisms = prey population declines
* death rate of prey»birth rate
stage 3 -
* reduced prey population can’t support large predator population
*intraspecific competition for food increases = decrease in predator population size
stage 4 -
* reduced predator numbers = less prey population killed
*more prey organisms survive and reproduce = increase prey population
CYCLE BEGINS AGAIN
Define conservation
the maintenance of biodiversity through human intervention or action
Define preservation
the maintenance of ecosystems in their original state - without interference and human use
What is the difference between preservation and conservation?
Conservation is an active process
Preservation is passive
Define reclamation
restoration of damaged ecosystems that have been degraded by human activity or impaired by natural disaster
What are 3 examples of conservation?
- Using grazing to keep Fen land from becoming woodland
- removal of invasive species like grey squirell
- legal hunting of animals in nature reserves to reduce population from potentially damaging levels