C4 Flashcards
What is a population?
An interacting group of organisms of the same species living in an area. Must be able to successfully breed.
What is a population size?
Number or estimated number of organisms in a population AT ONE TIME- constantly changing
What is a random sample?
A sample taken from an arbritrarily chosen zone, instead of using a predictable pattern.
What is a sampling error?
The difference between the estimated population size (from sample) and the real population size (difficult to quantify)
What is quadrat sampling?
Using a square of a particular dimension placed at a random location in the area. Organisms inside quadrant are counted. Useful for sessile organisms that cannot move.
Explain the process of quadrat sampling
- Put a measuring tape down along one or two edges of the target area
- Generate random numbers within the measuring units along transect
- First number determines the distance along transect
- Second number determines vertical distance
- Place a quadrat at that intersection
- Count every organism completely in quadrant
- Repeat and then multiply the sampled area to represent total area
What does the standard deviation tell us about the spread of the population?
Whether they are very spread out (large standard deviation) and occupy lots of area, or condensed in a small, specific area (small standard deviation)
Explain the process of capture-mark-release-recapture for motile organisms?
- In area, capture as many organisms with net, trap etc
- Mark each organism (mark must be non-toxic, non-washable and low visibility)
- Release organisms and wait (no-one dies, no one leaves/ comes and no marks dissolve)
- Recapture as many as possible (same #)
- Plug numbers into Lincoln Index
- High percent of recaptured are marked= smaller population size
What is the Lincoln Index and what do the letters represent?
P= N1xN2/R
P= Population size
N1= Size of first sample
N2= Size of second sample
R= Number of recaptures in the second sample
What is carrying capacity?
The maximum number of organisms that an environment can consistently meet the needs of
What is a limiting factor?
Any aspect or event that prevents a population from continuing to grow faster. Can also be something in finite availability that is needed for survival for many individuals in the community
Often gives rise to inter and intra specific competition
What is the difference between density dependent and density independent factors?
- Density dependent: factor that is much more significant or problematic in larger populations
- Density independent: factors that are unrelated/ not impacted by population size
What are the different types of density dependent factors?
- More predators
- Competition for food, water and space
- Faster spread of pathogens and parasites
How does exponential growth work- bacteria can do this?
- Both size and rate of growth continually increase due to abundant resources
- Use logarithmic scale on y-axis
- Only limiting factors are density independent factors- affect all populations no matter of size e.g natural disasters, climate change
- Can be caused by positive feedback loops which cause more growth
Explain the phases of a sigmoid growth curve.
- Exponential phase (rate increases)
- Transitional phase (size grows at a slower rate)
- Plateu phase (population stabilises at carrying capacity)- birth rate= death rate
* Population begins rapidly but rate of growth slows down until the size stabilises at carrying capacity
* Limited resources
* Impacted by independent factors but also density dependent factors
Bigger impact in crowded populations
Spread of disease, competition for food, water and shelter
Attract more predators
What is a community?
All of the populations in an area and their interactions e.g feeding, competition, and symbiotic relationships.
Can also be defined as the biotic factors of a habitat
What is herbivory?
An interspecific relationship where primary consumers feed on producers. Often does not kill producer, and can even be beneficial, but can sometimes kill small plants
What is predation?
Interspecific relationship involving one consumer species (predator) killing and eating another consumer species (prey). Necessary for population control
What is mutualism?
A type of symbiotic relationship where both species benefit from the relationship
What is a symbiotic relationship?
Ongoing close association between species
What is parasitism?
A type of symbiotic relationship where one organism (the parasite) lives on another organism (the host) and negatively affects them
What is pathogenicity?
Similar to parasitism, but causes disease to the host. Not usually ongoing, as the disease will kill organism or the organisms immune system will kill the pathogen
What is an endemic species?
A species that is naturally found in that area, a population in its natural habitat
What is an invasive species?
Alien species which rapidly reproduced and outcompeted endemic species. Have the threat to damage stable ecosystems
What is the difference between an interspecific and intraspecific relationship?
- Interspecific: between different species living in the same community
- Intraspecific: between members of the same species in a shared habitat
What are the types of intraspecific relationships
- Competition
- Cooperation
How does competition work in interspecific relationships?
Competition for a shared resource leads to competitive exclusion- elimination or niche partitioning
How does cooperation work in intraspecific relationships?
- Benefits all members
- Seen more in complex social animals (behavioural)
- Examples: huddling for warmth, pack hunting, schooling in fish, parenting young
How does competition work in intraspecific relationships?
- Live in the same niche
- When resources are limited, not all survive
- Drives natural selection, ensures survival of best adapted
- Stability at carrying capacity
- This results in a net positive for the population as only the best adapted survive
- Examples: Access to food, water and shelter