Unit 2: Species and Population Flashcards
Define Species
A group of organisms that share common characteristics and can interbreed to produce fertile offspring.
Define Population
A group of organisms of the same species living in the same area at the same time and which are able to interbreed.
Define Habitat
The environment in which a species usually lives.
Define Niche
Particular environment that offers the exact conditions that the species needs or has adapted to.
What are the Two Types of Niches?
1) Realized niche
2) Fundamental niche
Distinguish between the Realized and Fundamental Niche
Fundamental niche is the potential mode of existence of the species, the realized niche is the actual mode of existence of a species which results from adaptation.
Give an Example of a Niche
Rocky shore for barnacles in the North Atlantic: two species compete for habitat hence they establish in a realized niche.
What are Abiotic Factors?
The non-living components of an ecosystem.
What are Biotic Factors?
The living components of an ecosystem.
What are the Key Abiotic Factors of Marine Ecosystems?
- Salinity
- Temperature
- PH
- Dissolved oxygen
- Wave action
What are the Key Abiotic Factors of Freshwater Ecosystems?
- Turbidity
- PH
- Flow velocity
- Temperature
- Dissolved oxygen
What are the Key Abiotic Factors of Terrestrial Ecosystems?
- Temperature
- Light intensity
- Soil moisture
- Wind speed
- Soil particle size
- Soil mineral content
- Slope
- Drainage (porosity)
What are the Types of Population Interactions?
- Predation
- Herbivory
- Parasitism
- Mutualism
- Disease
- Competition
Distinguish between Interspecific and Intraspecific Competition
- Intraspecific: members of the same species
* Interspecific: different species for the same resources
What is Predation?
One species feeds on another which enhances fitness of predator but reduces fitness of prey (e.g. herbivory).
What is Parasitism?
The host provides a habitat and food for the bacteria, but in return, the bacteria cause disease in the host.
What is Mutualism?
A type of symbiotic relationship in which both species benefit from the relationship.
What is Competition?
The relationship between species that attempt to use the same limited resource.
What is Carrying Capacity?
The number of individuals in a population that the resources in the environment can support for an extended period.
What are Limiting Factors to Carrying Capacity?
- To plants: light, nutrients, water, CO2, temperature
* To animals: space, food, mates, nesting sites, water.
What are the Effects of Limiting Factors to a Population?
Will slow population growth as it approaches the carrying capacity of the system.
Distinguish between S- and J-curve
J-curves show exponential growth for populations establishing in a new habitat. S-curves show the establishment of a population into a new environment.
What are the Phases of Growth Curves?
1) Exponential growth phase
2) Transition phase
3) Plateau phase
Explain the Exponential Growth Phase
Limiting factors are not restricting the growth of a population.
Explain the Transition Phase
When limiting factors begin to affect the population restricting its growth.
Explain the Plateau Phase
Limiting factors restrict the population to its carrying capacity and changes in abiotic factors cause the population to remain stable around the carrying capacity level.
Define Community
A group of populations living and interacting with each other in a common habitat.
What is Photosynthesis? (+ Formula)
Transformation of light energy into the chemical energy of organic matter.
CO2 + H2O –> CHO + O2
What is Respiration? (+ Formula)
Breakdown of glucose using oxygen, releasing carbon dioxide, water and energy.
CHO + O2 –> CO2 + H2O
What is a Trophic Level?
The position an organism occupies in a food chain, or the position of a group of organisms in a community that occupy the same position in food chains.
Draw an Example of Food Web
(put picture from phone)
Distinguish between Food Chain and Food Web
A food chain shows the linear flow of nutrients and energy from one trophic level to another. A food web shows different food chains that are interconnected at many trophic levels.
What are the Trophic Levels?
1) Producer
2) Primary consumer
3) Secondary consumer
4) Tertiary consumer
Distinguish between Autotrophs and Heterotrophs
Autotrophs are organisms that are able to make their own food from raw materials and energy (aka producers). Heterotrophs are organisms that cannot make their own food (aka consumers) and hence feed on producers or other consumers.
What are Decomposers?
Organisms that feed on dead materials and recycle nutrients in the ecosystem.
What is Biomass?
The amount of biological matter in a living or recently living organism, measured in units of mass per unit area (gm^-2).
List the Three Types of Ecological Pyramids
1) Numbers
2) Biomass
3) Productivity
What does the Pyramid of Numbers Show?
Represents the number of organisms coexisting in an ecosystem; it is constructed by counting the number of organisms at each trophic level.
Evaluate the Pyramid of Numbers
Pro: show changes over time + overview of structure
Con: doesn’t consider size of org. or omnivores
What does the Pyramid of Biomass Show?
Shows the biological mass at each trophic level; biomass is estimated at a particular time, dry mass is multiplied by number of organism for each trophic level.
Evaluate the Pyramid of Biomass
Pro: considers size
Con: killing organisms for sampling + season variation
What does the Pyramid of Productivity Show?
Refer to the flow of energy through trophic levels and always show a decrease in energy along the food chain.
Evaluate the Pyramid of Productivity
Pro: can compare ecosystems + no inversion
Con: difficult to collect data + omnivores
What Unit of Measure is Used for Biomass?
gm^-2
What Unit of Measure is Used for Productivity?
gm^-2 yr^-1
How does Entropy Affect the Structure of an Ecological Pyramid?
The law states that when energy is transformed some of it is lost; in ecosystems the losses are due to respiration. On average, ecological efficiency is 10%; because it is so low each trophic level has a successively smaller energy pool therefore there can only be four/five trophic levels.
What is Bioaccumulation?
The build-up of a persistent pollutant within an organism or trophic level because it is not biodegradable.
What is Biomagnification?
The increase in concentration of persistent pollutants along a food chain (persistent bioaccumulation causes biomagnification).
What is Productivity?
The conversion of energy into biomass in a given period of time.
What is Ecological Efficiency?
The percentage of energy assimilated in one trophic level that is available to be passed to the next.
What is Primary Productivity?
A measure of the conversion of light into chemical energy in living organisms.
Distinguish between Gross Primary Productivity (GPP) and Net Primary Productivity (NPP)
GPP is the total energy converted by photosynthesis (rate at which photosynthesis occurs). NPP is the gain by producers in energy or biomass minus respiratory losses.
State the Formula for GPP
NPP + R
State the Formula for NPP
GPP - R
What is Secondary Productivity?
The biomass gained by consumers as they feed.
Distinguish between Gross Secondary Productivity (GSP) and Net Secondary Productivity (NSP)
GSP is energy gained through absorption by consumers. NSP is the gain in energy or biomass minus respiration losses (the biomass available for the next trophic level).
State the Formula for GSP
Food eaten – Fecal losses
State the Formula for NSP
GSP – R
What is Maximum Sustainable Yield (MSY)?
The largest amount of a raw material that can be taken without permanently depleting the stock.
What is the Relationship between MSY and Productivity?
MSY is equivalent to the NSP or NPP of a system.
What are the Storages of the Carbon Cycle?
- Organisms
- Forests
- Atmosphere
- Soil
- Fossil Fuels
- Oceans
What are the Transfers in the Carbon Cycle?
- Feeding (on producers/consumers/organic matter)
* CO2 dissolving in rainwater/ocean
What are the Transformations in the Carbon Cycle?
- Photosynthesis
- Respiration
- Combustion
- Fossilization
What are the Storages of the Nitrogen Cycle?
- Organisms
- Forests
- Soil
- Fossil fuels
- Atmosphere
- Water bodies
What are the Transfers in the Nitrogen Cycle?
- Feeding (on producers/consumers/organic matter)
- Absorption of plants from soil into roots
- Removal of metabolic waste
What are the Transformations in the Nitrogen Cycle?
- Nitrogen fixation (atmosphere nitrogen = ammonium)
- Lightning (atmosphere nitrogen = NO3).
- Nitrification (bac. ammonium = nitrate + nitrate)
- Denitrification (bac. nitrates = nitrogen)
- Deamination (decomposers nitrogen = ammonia)
- Assimilation (nitrates absorbed by plants)
What Human Activities can Alter the Carbon Cycle?
- Urbanization
- Deforestation
- Agriculture
- Fossil fuels
What Human Activities can Alter the Nitrogen Cycle?
- Agriculture (fertilizers + trade of crops with nitrogen)
- Haber process (manufacturing of fertilizer)
- Deforestation
- Fossil fuels
- Population growth
What is a Biome?
A group of ecosystems that share similar climatic conditions and therefore similar patterns of vegetation.
List the Five Major Classes of Biomes
1) Aquatic
2) Grassland
3) Tundra
4) Forest
5) Desert
What are the Types of Aquatic Biomes?
- Marine (ocean, estuaries, swamps, coral reefs)
* Freshwater (ponds, lakes, rivers, wetlands)
What are the Characteristics of a Freshwater Biome?
- Low salt concentration
- Temperatures vary with seasons (cooler at source)
- Contains flowing water
- Mouth of river has sediment and debris = low light pen.
What are the Characteristics of a Marine Biome?
- High diversity
- Evaporation rates contribute to water cycle
- High productivity = absorb CO2 and release O2
- Abyssal zone = no light pen + low temp and nutrients
What are the Types of Forest Biomes?
- Temperate forest
* Tropical rainforest
What are the Characteristics of a Temperate Forest Biome?
- Mild climate
- Lower temp and rainfall than tropical rainforest
- Lower NPP of tropical rainforest
- High leaf litter + nutrients recycled rapidly
- Many herbivore species
What are the Characteristics of a Tropical Rainforest• Biome?
- High temp + rain + insolation
- Biome with highest productivity
- High biodiversity (+ high competition for light)
- Low nutrient levels in soil
- High decomposition + run-off
What are the Types of Grassland Biomes
- Prairies
- Steppes
- Savannah
What are the Characteristics of Grassland Biomes?
- Wet and hot season (+ dry/warm)
- Productivity is lower than forest biomes
- Long dry seasons lower productivity
- High biodiversity
- Savannah soil have low nutrients
- Prairie soil have high nutrients (used for agriculture)
What are the Types of Desert Biomes?
- Arid
- Semi-arid
- Coastal
- Cold
What are the Characteristics of Desert Biomes?
- Very low rainfall
- Hot days and cold nights
- Low productivity and biomass
- Soil has low-water holding capacity and fertility
- Vulnerable to soil erosion from wind
What are the Types of Tundra Biomes?
- Arctic
* Alpine
What are the Characteristics of a Tundra Biomes?
- Low temperatures
- Low biomass and productivity (frozen permafrost)
- Seasonal sunlight and short day length
- Water resources limited (locked in ice)
What are the Main Factors Governing the Distribution of Biomes?
- Temperature
- Precipitation
- Insolation
What is the Tricellular Model of Atmospheric Circulation?
Model that explains the distribution of precipitation and temperature and how they influence structure and productivity of different biomes.
What Cells is the Tricellular Model Made of?
1) Hadley cell (tropical climate – hot air)
2) Ferrel cell (desert + temperate biome – dry air)
3) Polar cell
What is the Inter-tropical Convergence Zone?
The meeting place of the trade winds from the northern and southern hemisphere; a low pressure area where the trade winds, which have picked up heat, are forced to rise by convection currents.
What is Biome Shifting?
Changes in temperature and precipitation, and resultant changes in vegetation and habitat within a biome. E.g. In Africa in the Sahel region, woodlands are becoming savannas.
Define Succession
A long-term process in which communities in an area change over time.
State the Stages of Primary Succession
1) Pioneer communities
2) Intermediate communities
3) Climax communities
Explain Succession with Reference to a Named Example
Succession in sand dunes:
• Pioneer specie: sea holly – tolerant of salt + sand
• Marram grass creates embryonic dunes + reduce salt
• Marram grass dies = decomposition = soil nutrients
• Trees + shrubs + rabbits = excretion = nutrients
• Accumulation of organic matter = woodland
• No climax = stable state ecosystem
Distinguish between K- and R-Strategists
K-strategists are organisms that produce few offspring but care for them a long time. R-strategists are organisms that produce large numbers of offspring but do not spend time or energy caring for them.
What are the Characteristics of K-Strategists? (+ Example)
Example: gorilla • Large in size • Late maturity and reproduction • Large amount of parental care • Few offspring • Long lifespan • S-population growth species
What are the Characteristics of R-Strategists?
+ Example
Example: frog • Small in size • Early maturity and reproduction • Little or no parental care • Large number of offspring • Short livespawn • J-population growth species
Contrast the Characteristics of Pioneer and Climax Communities
Organic matter: small vs large Soil quality: immature vs mature Nutrient conservation: poor vs good Nutrient cycle: open vs closed Stability: low vs high Biodiversity: low vs high Organisms: r-strategists vs k-strategists Life cycles: simple vs complex
How does Productivity Change within Succession?
In pioneer communities GPP is low due to the low density of producers, whereas NPP is high as respiration is also low. In later stages NPP decreases and GPP increases (as with more organisms respiration increases). In climax communities productivity stabilizes to the ratio P:R (production : respiration) which is equal to 1 (hence NPP is 0).
What is Secondary Succession?
Takes place after an area of land has been cleared and soil is already present.
What are the Components of Stability?
1) Resistance (ability to be the same after disturbance)
2) Resilience (ability to recover after disturbance)
3) Diversity (number and abundance of species)
What Factors can Affect the Stability of an Ecosystem?
- Disturbance frequency and intensity
- Species diversity (+ r-strategists vs k-strategists)
- Trophic complexity (complex = stable)
- Rate of nutrient and energy
What Human Activities can Impact Succession?
- Agriculture (+ grazing)
- Habitat destruction
- Deforestation
- Fossil fuels = climate change (biome shifting)
Define Resilience
The tendency of a system to avoid tipping points and maintain stability through steady-state equilibrium.
What is Zonation?
Changes in community along an environmental gradient due to changes in altitude, latitude, tidal level or distance from shore (coverage by water).
Explain Zonation with Reference to a Named Example
Mangrove species zonation on shoreline: • Closest to water= red + black mangrove • Elevated from shore = white mangrove • Highest elevation = buttonwood Increase towards shore: salinity, soil stability, sediment
How and Why is Temperature Measured?
Measured with a thermometer or probe. Factors dependent on temperature include:
• Enzymes (metabolism)
• Solubility of oxygen in water (high = less soluble)
How and Why is Light Measured?
Measured with an electronic light meter. Influences the productivity and availability of energy in an ecosystem.
How and Why is pH Measured?
Measured with an electronic pH meter or chemical test (e.g. universal indicator). It is important for fish species in aquatic ecosystems + soil systems for plants.
What Types of Sampling can be Used?
1) Random (when area is fairly uniform)
2) Stratified (taken at fixed intervals)
3) Systematic (different areas inside the habitat)
Distinguish between Motile and Non-Motile Organisms
Motile organisms can actively move under its own power to different places. Non-motile organisms cannot move or are very slow.
How can Non-Motile Organisms be Measured?
Quadrat methods including:
• Percentage frequency (n species found/n quadrats)
• Percentage cover (proportion of quadrat with specie)
• Population density (n organisms/area of quadrat)
How can Motile Organisms be Measured?
Capture-mark-release-recapture with the Lincoln Index.
What is the Lincoln Index? (+ Formula)
An indirect method by which the size of an animal population can be estimated = (n1 x n2) / nm Where: n1 = number marked in sample 1 n2 = total number captured in sample 2 nm = number marked in sample 2
What are the Disadvantages of the Lincoln Index?
- Risk of harming animals/alter behavior
- Mark may be toxic to some animals
- Mark may rub off
- Mark may attract or distract from predation
How can Biomass be Calculated?
Using the extrapolation technique:
1) Sample of biological material is extracted
2) Sample is weighed, put into an oven, reweighed.
5) Process is repeated until the weight is the same
6) Mass of org x total number of org = total biomass
What is Species Diversity?
The number of different species and the relative numbers of individuals of each species.
How is Diversity Measured within an Ecosystem?
Using the Simpson Diversity Index
What is the Simpson Diversity Index? (+ Formula)
A measure used to quantify the biodiversity of habitat.
N(N - 1) / E n(n - 1)
Where:
N = total number of organisms of all species
n = number of individuals of specific species
Distinguish between Species Richness and Evenness
Species richness refers to the number of species present. Species evenness refers to how relatively abundant each of the species are.
What is an Ecological Gradient?
A gradual change in abiotic factors through space (or time) + found where two ecosystems meet or one ends.
How can Ecological Gradients be Measured?
Using transects:
• Continuous transects or interrupted
• Line transect (records all organisms touching tape)
• Belt transect (same as line but wider line)
What are the Types of Quadrats?
- Frame (empty frames of known area)
- Grid (frames divided in 100 small squares)
- Point (frame with 10 holes for sampling layers of veg)
