Populations Flashcards
(19 cards)
1
Q
carrying capacity
A
maximum population size that an environment can support
2
Q
phases of population growth curve
A
- slow growth - small no.s of individuals initially present begin reproducing - birth rate higher than death rate
- rapid growth - no. of breeding individuals increases, total population multiplies exponentially
- stable state - population growth limited by external constraints, population size fluctuates but overall size remains stable, birth and death rates equal
3
Q
abiotic factors that can affect population size
A
- natural disasters
- water/oxygen availability
- rainfall
- temperature
- light
- pH
4
Q
biotic factors that affect population size
A
- competition
- predators
- disease
5
Q
immigration
A
- movement of organisms into an areas, increasing population size
6
Q
emigration
A
- movement of organisms away from an area, decreasing population size
7
Q
density independent factors
A
- factors which have an effect on population regardless of its size
- can dramatically change population size
- eg. earthquakes, volcanoes, storms
8
Q
k-strategist
A
- limiting factors exert their affect as population grows closer to the carrying capacity
- population gradually levels out
- low reproductive rate, slow development, long lifespan, large body mass
- eg. humans, elephants, lions, sharks
9
Q
r-strategist
A
- population size increases too rapidly that it exceeds carrying capacity
- not enough resources to survive/reproduce
10
Q
interspecific competition
A
- between different species
- occurs when they’re competing for the same resource resulting in reduction in the resource available to both populations
- leads to smaller populations
- if one species is better adapted, the other can become outcompeted, if conditions remain the same it can no longer exist - competitive exclusion principle
11
Q
intraspecific competition
A
- between members of the same species
- availability of the resource determines the population size
- results in fluctuations in population size
- graph shows no. organisms rising, falling and rising again
1. resources are plentiful for survival of all organisms - population increases
2. increased population means not enough resources are available to support them, population decreases
3. less competition as less organisms competing for same resources
12
Q
predator-prey relationship on graph
A
- increase in prey - more food for predators to survive and reproduce, increased predators
- increased predators eat more prey - decrease in prey population
- reduced prey population - not enough food for predators, intraspecific competition for food increases, decrease predator population
- decreased predators - more prey survive, increased prey population
13
Q
conservation
A
- maintenance of biodiversity through human action or management
- natural resources can be used without running out
- reclaimation - restoring ecosystems that have been damaged or destroyed
14
Q
preservation
A
- protection of an area by restricting human interference so the ecosystem is kept in its original state
- eg. newly discovered caves
15
Q
economic, social and ethical reasons for conservation
A
economic
- provide resources for humans to survive and get income eg. rainforests provide medicines, wood, food
social
- people enjoy the natural beauty of wild ecosystems eg. bird watching, cycling
ethical
- all organisms have the right to exist
- humans should not have the right to decide which organisms can survive
16
Q
aims of sustainability
A
- preserve environment
- ensure resources available for future generations
- humans live comfortably
- enable less economically developed countries to develop through exploiting natural resources
- create balance in consumption of resources between more and less EDCs
17
Q
coppicing
A
- technique to produce sustainable timber
- tree trunk cut close to ground, new shoots form from cut surface and mature
- these shoots are then cut and more are produced in their place
18
Q
techniques of large scale timber production
A
- selective cutting - removing only largest trees
- replace trees through replanting
- plant trees at optimal distance apart to reduce competition - higher yields
- manage pests and pathogens
- areas of forest remain for indigenous people
19
Q
techniques of sustainable fishing
A
- fishing quotas to limit no.s of species of fish allowed to be caught in an area
- using nets with different mesh sizes eg. large enough for immature fish to escape
- allowing it at only certain times of year - protects breeding season of some fish
