Chapter 19 Flashcards
What is ecology?
Study of inter-relationships between organisms and their environment
What are the Abiotic factors?
Non-living factors e.g weather, temperature
What are the biotic factors?
Living factors e.g competition and predation
What are ecosystems?
are dynamic systems made up of a community and all non-living factors of its environment
Can range from small -> large
Within ecosystem, there are a number of populations
What major processes should you consider within an ecosystem?
Flow of energy
Flow of elements
What is a population?
Group of individuals of one species that occupy the same habitat at the same time + is potentially able to interbreed
Why do the sizes of populations vary?
Because of
Effect of abiotic factors
Interactions between organisms
An ecosystem su[ports a certain size of the population of a species called the…
Carrying Capacity
What is a community?
all the populations of different species living and interacting in a particular place at the same time
What is a habitat?
the place where an organism normally lives and is characterized by physical conditions + other types of organisms present
What is a microhabitat?
Within each habitat, there are smaller units, each with their own microclimate
What is a niche?
Describes how an organism fits into the environment
Refers to whrre organism lives and what it does there
Includes biotic and abiotic conditions to which an organism is adapted in order to survive, reproduce + maintain the variable population
What is the exclusion principle?
No two species occupy exactly the same niche
What is the population size?
The number of individuals in a population
When should you use LOG in a graph and why?
To represent bacteria
The bacteria double and eventually, without log, the curve would run out of the graph
What are some limiting factors that can affect the population size of a single photosynthetic bacterial cell?
- Mineral ions consumed as population increases
- The population becomes so large that bacteria at surface block light from reaching deeper levels
- other species introduced, competes for light or minerals
- Winter brings lower temp, lower light intensity
State abiotic factors and what it affects?
Tempreature- Each species has a different optimum temperature at which it is best able to survive
Light- Ultimate source if energy
pH- Affects the action of enzymes
Water + humidity- Where H2O is scarce populations consist of species well adapted to living in dry conditions
How does competition result?
When two or more individuals share any resource that is insufficient to satisfy all their requirements fully
What is intraspecific competition?
When competition occurs between members of the same species
What is interspecific competition?
When competition occurs between members of different species
What is the competitive exclusion principle?
States that where two species are competing for limited resources, the one that uses these resources most efficiently will ultimately eliminate the other
(No two species can occupy the same niche when resources are limited)
What happens to a population of two species that are in competition?
- One will normally have an advantage over the other
- This population will increase while other will diminish
- If conditions remain the same, this will lead to complete removal of one species
How can you show that a factor influences the size of a population?
Link it to birth and death rate
What is a predator?
an organism that feeds on another organism, known as their prey
How have predators evolved and become better adapted to catch their prey?
Faster movement
Effective camouflage
Better means at detecting prey
How have prey become better adapted to avoid predators?
Better camouflage
Protective features
Compare the difference between the predator prey relationships in a lab and nature?
In lab
Prey is exterminated by predator because range and variety of the habitat is limited to the confinement of the lab
Does not reflect what happens in the wild
In Nature
area which population can travel is greater + variety of environment is diverse
Prey can escape predation -> harder to find and catch
Describe the effect of predator-prey relationship on population size?
1) Predator eats prey -> reduces prey population size
2) With fewer prey available, predators are in greater competition with prey thats left
3) Predator population is reduced as some predators are unable to obtain enough prey to survive + reproduce
4) Fewer predators left + fewer [prey eaters + so more would survive and reproduce
5) Prey population increases and are available as food so predator population increases
What other factors can cause a fluctuation in populations?
disease
climate factors
What causes selection pressure?
Periodic population crashes
How does a population evolve to be better adapted to the prevailing conditions?
Individuals who can escape predators, withstand disease and are more likely to survive and reproduce
What is abundance?
The number of individuals of a species in a given space
How do you decide what size quadrat to use?
- Larger species require larger quadrats
- Unevenly distributed species throughout large area -> small quadrat would give representative results
The larger the number of sample quadrats…
the more reliable the results
Describe the method of random sampling?
1) Lay out two long tape measurements at right angles, along two sides of the study area
2) Obtain a series of co-ordinates by using a random numbers taken from a table generated by a computer
3) Place a quadrat at the intersection of each pair of coordinates and record the species within it
Describe the method of systematic sampling?
1) Belt transect made by stretching string/tape across the ground in straight line
2) A frame quadrat laid alongside the line + species within it is recorded
3) Its then moved along length along the line and process is repeated
(Gives record of species on a belt)
Describe the method of measuring abundance using frequency?
-Likelihood of particular species in quadrat
Gives quick idea of species present and general distribution in area
Does not provide info on density + detailed distribution of species
Describe the method of measuring abundance using % cover?
-Estimate of area within quadrat that a particular plant species cover
Data can be counted rapidly + individual plants do not need to be counted
Less useful where organisms occur in several overlapping layers (plants)
How are reliable results obtained?
Large sample size (More representative)
Many quadrats
Mean of all samples obtained
Methods of measuring abundance works well with?
Non motile / slow organisms
Describe how Mark release recapture method works?
Known number of animals are caught
They are marked in some way
They are released back into the community
Some time later a given amount of individuals are collected randomly + number of marked individuals are recorded
How is the size of population calculated?
PZ = S1 x S2 / Marked individuals
What assumptions is the Mark release recapture method done with?
- Proportion of marked to unmarked in second sample is the same as proportion of (M to umk) as a whole
- Marked individuals released from first sample distribute themselves among remainder population + have enough time to do so
- there is no immigration into or out of population
- There are few deaths + births
- Method of marking is not toxic or make it conspicuous to predation
- Mark/label isn’t rubbed off
What is succession?
Used to describe the changes in populations as they fluctuate (rapidly or slowly) overtime, in species that occupy a particular area
How may species alter the environment when it colonises an area?
- Makes it less suitable for existing species (New species may out compete existing ones)
- More suitable for other species with different adaptations (may out compete with better adapted species)
Series of succession changes alter abiotic environment which can result in?
- Less hostile environment that makes it easier for other species to survive
- As a consequence new communities are formed + biodiversity may be changed or increased
What is the pioneer species?
Colonisation of an inhospitable environment
What features of pioneer species suit them to colonisation?
Asexual reproduction Vast quantities of wind dispersed seeds or spores Rapid germination of seeds Ability to photosynthesise Ability to fix nitrogen from atmosphere Tolerance to extreme conditions
What is climax community?
A balanced equilibrium of species and remains more or less in a stable state over time
What are the common features that occur during any succession?
Non-living (abiotic) environment becomes less hostile
Greater number + Variety of habitats + niches
Increased biodiversity
More complex food webs
Increased biomass
It is the abiotic factors that determine…..
the dominant species in a community
What is secondary succession?
When land with already sustained life is suddenly altered the ecosystem returns to climatic community
What are the stages of succesion?
Barren land -> Primary colonizers -> secondary -> tertiary -> scrub land -> climatic climax
Land altered
What is conservation?
The management of earths natural resources by humans in such a way that maximum use of them can be made in future.
Involves active interaction of humans
Dynamic process - careful management of existing resources + already damaged activities
What are the main reasons for conservation?
- Personal
- Ethical
- Economic
- Cultural + aesthetic
What way can you conserve habitats?
Managing succession
