Topic 7 - Populations In Ecosystems Flashcards
What is a community?
Consists of all the populations of different species living together in a habitat and interacting with one another.
What are the five key features of communities?
- Biodiversity.
- Interactions (predation, competition and mutualism).
- Habitat.
- Stability.
- Niche.
What are biotic factors?
The living components of an ecosystem that influence populations and communities.
What are four examples of biotic factors?
- Food availability: abundance or scarcity of food resources affects population size
- Pathogens: depressants of disease causing organisms can reduce population numbers.
- Predators: predator interactions influence population dynamics
- competition: competition affects survival and reproduction
What are abiotic factors?
The nonliving aspect of an ecosystem that affect organisms living there.
What are five examples of abiotic factors?
- temperature: optimum temperature needed for survival extreme temperatures affect metabolic processes.
- Light intensity: crucial for photosynthesis in plants
- pH: affect enzymes activity
- Water availability: scarce water supply limits population size to only species adapted to dry conditions
- humidity: high humidity reduces transpiration rates in plants conversely low humidity support only species adapted to dry environments
What is the interaction between a biotic and biotic factors?
Abiotic factors directly influenced biotic factors for example temperature affects the activity of predators and pray.
What is carrying capacity?
The maximum stable population size of a species that an ecosystem can support over a long period. It depends on the availability of resources and the balance between biotic and abiotic factors.
How do biotic factors affect carrying capacity?
Competition:
- intraspecific: members of the same species complete for limited resources reducing population growth as numbers approach carrying capacity
- interspecific: different species compete potentially excluding one species if resources are limited
- predation: predators control prey population maintaining balance
- Disease: high population density increases the spread of disease limiting growth
How do you investigate non-motile organisms?
Using quadrats or transects
How does a quadrat work?
- quadrat are randomly placed within the study area to avoid bias
- The abundance of organisms is recorded in the quadrat
How does a belt transact work?
Quadrat are placed systematically along a line to measure changes across a gradient.
How can you estimate motile organisms abundance?
Mark-release-recapture method is used.
What is the mark – release – capture method?
- Capture a sample of the population am mark them in a way that does not harm or affect behaviour.
- Marked individuals back into their habitat and allow time for them to mix evenly with the rest of the population.
- We capture a second sample of how many unmarked..
What is the population size formula for estimating motile organisms?
Population size = (number in first sample) x (number in second sample)/ number of marked individuals in the second sample.
What are the six assumptions of the mark-release-recapture method?
- The proportion of the marked individuals in the second sample is representative of the entire population
- Marked individuals have mixed evenly within the population
- There is no immigration
- There is no significant births or deaths
- the mark is non-toxic and does not increase predation risk
- Marks remain visible and do not wear off before we capture
What is meant by distribution of a species?
Where species are found with an ecosystem it’s affected by both biotic and abiotic factors.
What is meant by abundance of a species?
The number of individuals of a species in an ecosystem influenced by resource availability competition and environmental conditions.
What is primary succession?
Occurs in areas where there was no previous life.
What is a pioneer species?
The first organism to colonise the area they are adapted to survive harsh conditions. (Lichens)
What is the process of primary succession?
Pioneer species colonises the area they then die and decompose forming humus creating basic soils that retain water and support other life forms.
Larger plants begin to colonise as soil quality improves larger plants like grasses and shrubs grow.
It finally reaches a climax community
What is a climax community?
The final stable community is reached, comprising larger trees and complex ecosystems.
What is secondary succession?
- in areas where a community previously existed but was cleared
- So you already exist so the process starts at a later stage than primary succession
- Progression to the climax community occurs more quickly
What are the three key features of succession?
- biodiversity increases over time as conditions improve
- Abiotic factors become less extreme
- Interaction between an organisms increase leading to more stable community
What is the lag phase of microbial growth?
- No immediate increase in population as microorganisms adjust their new environment
- cells are metabolically active synthesis enzymes and other molecules for growth.
What is the log phase of microbial growth?
- microorganisms grow and divide at their maximum rate under optimum conditions.
- Population size doubles and regular intervals.
- Nutrients are plentiful and waste products are minimal.
What is the stationary phase of microbial growth?
- growth rate slows as nutrients become limited and waste products accumulate.
- Birth rate equals death rate to the population size remains constant.
What is the death phase of microbial growth?
- nutrients are depleted and waste products reach toxic levels
- Death rate exceeds birth rate causing decline in population size
What are the five factors affecting microbial growth?
- Temperature
- PH
- Nutrient availability.
- Oxygen levels - aerobic organisms.
- Water availability - essential for metabolic processes or else can become dormant and die
What is conservation?
The management of the Earth natural resources to ensure their sustainable use whilst protecting biodiversity for future generations.
What four ways can conservation occur?
- Preserving habitats
- Preventing extinction.
- Maintaining ecosystem services.
- Managing succession.
How does preventing habitats achieve conservation?
- Ensure species survival by maintaining restoring their natural habitats
How do you preventing extinction achieve conservation?
Conserving endangered species through captive breeding programs, seed banks and habitats restoration.
How does maintaining ecosystem services achieve conservation?
Services such as pollination and climate regulation and nutrient cycling are vital for human survival and agriculture.
How is managing succession achieving conservation?
- human activities such as controlled burning or grazing are used to halt succession maintaining a specific habitat like Heathlands or grassland. This prevents the development of climax community which might reduce habitat diversity.
How can we balance agriculture with conservation?
Conservation strategies include rational, grazing hedge planting and agroforestry to increase biodiversity ensuring productivity.
What is species distribution?
Refers to how organisms are spread across a particular habitat or ecosystem.
How can you measure light intensity soil pH temperature, and moisture content?
Light intensity – measured using a light meter
Soil pH – tested with a pH probe or indicator
Temperature – recorded using a thermometer
Moisture content – measured using a soil moisture proof
What is autosomal linkage?
The occurrence of two or more genes on the same autosome, making them more likely to be inherited together due to reduced crossing over during mitosis.
What is an autosome?
A chromosome that is not a sex chromosome.
What is epistasis?
A relationship where the expression of gene is influenced by another gene.
What is a gene?
A section of DNA coding for a polypeptide or functional RNA.
What is a habitat?
The specific environment where an organism lives.
What is a predator?
An organism that hunt and consumes other organisms.
What is prey?
An organism that is consumed by predators.
What is a species?
A group of similar organisms capable of reproducing living fertile offspring.
What is variation?
Differences among individuals due to genetic factors, environmental factors or combination of both.
