B24 - Populations and sustainability Flashcards
1
Q
What are limiting factors?
A
- environmental resource/constraint that limits the population growth (prevents the population from rising above a certain level)
2
Q
What is the population growth curve?
A
- phase 1: slow growth
- small no. of individuals that are initially present reproduce
- birth rate is greater than the death rate which causes an increase in population size
- phase 2: rapid growth
- as no. of breeding populations increase, total population multiplies exponentially
- there are no constraints limiting this
- phase 3: stable state
- external constraints causes population size to fluctuate (overall size stays the same)
- birth/death rates are equal
- slight increases and decreases can be due to the fluctuations in limiting factors (e.g. predators)
3
Q
What do limiting factors do?
A
- they can prevent further growth of a population (and in some cases cause it to decline)
4
Q
What are abiotic limiting factors?
A
- temperature
- light
- pH
- availability of water/oxygen
- humidity
5
Q
What are biotic limiting factors?
A
- predators
- disease
- competition
6
Q
What is carrying capacity?
A
- it is the maximum population size that an environment can support
7
Q
What is migration?
A
- immigration:
- movement of individual organisms into a particular area (increases population size)
- emigration:
- movement of individual organisms away from a particular area (deceases population size)
8
Q
What are density dependent factors?
A
- factors that have an effect on the whole population regardless of its size
- can dramatically change population size
- earthquakes
- fires
- volcanic eruptions
- storms
9
Q
What are the types of competition?
A
- interspecific:
- competition between different species
- intraspecific:
- competition between members of the same species
10
Q
What is interspecific competition?
A
- where two or more different species of organism compete for the same resource
- this results in the reduction of the resource available for both populations
- less food will lead to organisms with less energy (to grow/reproduce)
- this results in smaller populations
- if one species of organism is better adapted, then the less adapted one will be outcompeted
- the less well adapted species will the decline in number and eventually die out in the habitat with the better adapted species
11
Q
What is competitive exclusion principle?
A
- where two species are competing for limited resources, the one that uses them more effectively will eventually eliminate the other
12
Q
What is an example of interspecific competition?
A
- competition between red and grey squirrels for food and territory
- grey squirrel was introduced in the UK and it’s pop. quickly increased
- this caused the decrease in red squirrel pop. size
- since grey squirrel can eat a wider range of food than the red squirrel as it is larger
- this increases its chance of survival and its ability to reproduce which then increases its pop.
- a further increase will reduce the food supply available to the red squirrels which reduces their ability to survive and reproduce
13
Q
What is intraspecific competition?
A
- where members of the same species compete for the same resource
- the availability of the specific resource determines the population size
- greater availability = larger population
- results in fluctuations over time
14
Q
What is the intraspecific graph?
A
- stage 1:
- when resource is plentiful, all organisms have enough of the resource to survive and reproduce
- this results in an increased population size
- stage 2:
- the increased pop. means that there are more individuals to share the food/space available
- this limits the resources and will cause the population size to decrease
- stage 3:
- less competition due to the smaller population size (less organisms competing for same resource)
- more organisms survive and reproduce (pop. growth)
15
Q
What is predation?
A
- where an organism (predator) kills and eats another organism (prey)
- type of interspecific competition
- they have evolved to become highly efficient at capturing prey (fast reactions, stealth)
- ** prey have also evoked through camouflage, mimicry etc. **
16
Q
What is the predator-prey graph?
A
- same pattern in general (peaks and troughs mirror each other)
- stage 1:
- increase in prey population provides more food for the predators
- allows them to survive and reproduce (increases predator pop.)
- stage 2:
- increased predator pop. eats more prey organisms (decline in prey pop.)
- death rate of prey population is greater than its birth rate
- stage 3:
- reduced prey population can no longer support the large predator population
- intraspecific competition for food increases (decrease in predator pop.)
- stage 4:
- reduced predator numbers results in less prey pop. being killed
- so more prey organisms survive and reproduce (increasing prey pop.)
** other factors can also affect this (availability of food plants of the prey, presence of other predators) **
17
Q
What is conservation?
A
- the maintenance of biodiversity through human action or management so that natural resources can be used without running out
- diversity between species, genetic diversity within species, habitats
- maintain sustainable development
- reclamation = process of restoring ecosystems that have been damaged/destroyed
