Topic 5 - On The Wild Side Flashcards
Define ecosystem…
All of the organisms living in a particular area and all the non living factors.
(Biotic and abiotic)
Define habitat…
The place where an organism lives
Define population…
All the organisms of one species in a habitat
Define community…
All of the organisms of a different species that live in the same habitat and interact with each other
Why does population size (abundance) vary?
Abiotic factors and biotic factors
How do abiotic factors affect abundance by increasing it?
- amount of light, water or space available, the temperature of their surroundings or the chemical composition of their surroundings
- when abiotic factors are ideal for a species they can grow fast and reproduce successfully e.g. when the temp of a mammals surroundings is the ideal temperature for metabolic reactions, they dont have to use up as much energy maintaining their body temp. More energy can be used for growth and reproduction so population increases.
How is abundance decreased because of abiotic factors?
- when abiotic conditions arnet ideal for a species organisms cant grow fast or reproduce as successfully.
-e.g. when the temp of a mammals surroundings is significantly lower or higher that their optimum body temp. This means less energy will be available for growth and reproduction so population will decrease
What are the biotic factors that affect population size?
- inter specific competition
-intraspecific competiton - predation
What is interspecific competition?
Competition between different species
What is the consequence of interspesific competition?
- different species compete for the same resources e.g. food and habitat
- this means that resources available to both species are reduced
- both populations will have less food therefore less energy for growth and reproduction so the population will be lower for both species
What is intraspecific competition?
Competition within a species
What are the consequences of intraspecific competition?
- same species compete for same resources
- the population of the species will increase when resources are plentiful, as population increases there’ll be more organisms competing for the same amount of space and food
- eventually food and space become limiting, there isn’t enough so population begins to decline
- a smaller population means less competiton for space and food which increases growth and reproduction so population starts to grow again
What is carrying capacity in intraspecific competition?
The maximum stable population size of a species that an ecosystem can support
What is predation?
An organism kills and eats another organism.
The population sizes of predators and prey are interlinked, as one changes the other also changes
How does predation affect population?
- as prey increases there’s more food for predators so the predator population grows
- as predator population increases more prey is eaten so prey population falls.
- less food for predators so population decreases
Why does distribution vary?
Abiotic and biotic factors
What is a niche?
The role a species plays within its habitat
What does a niche include?
Biotic interactions - what the organism eats
Abiotic interactions - the oxygen the organism breathes in and the co2 it breathes out
Does every species occupy its own niche?
Yes
Explain the abundance of different species by using the niche concept…
Two species occupying a similar niche will compete so fewer individuals of both species will be able to survive
Explain the distribution of different species by using the niche concept…
Organisms can only exist in habitats where all the conditions to make up their role to exist
Define abundance:
The number of individuals of one species in a particular area
Define distribution:
Where a particular species is within an area you’re investigating
What are the benefits of random sampling?
Reduces bias
What is systematic sampling?
A type of non-random sampling. Where samples are taken at fixed intervals, often along a line
- e.g. quadrants could be placed along a line (transect) in an area where abiotic factors change gradually
What can frame quadrats be used to investigate?
Immobile populations
How do frame quadrats work?
- square frame, usually divided into a grid of 100 smaller squares
- placed on the ground within an area you’re investigating
- in random sampling you can select random coordinates
- the number of individuals of each species is recorded in each quadrat
- the % cover of a plant species can be measured by how much of the quadrat is covered by a plant species
What can point quadrats be used to investigate?
Investigate plant populations
How do point quadrats work?
- horizontal bar on two legs with a series of holes at sent intervals along its length
- places on the ground at random points within the area you’re investigating
- pins are dropped through the holes in the frame abd every plant that the pin touches is recorded
-number of individuals in each quadrat is recorded
How can percentage cover be calculated when using a point quadrat?
Calculating the number of pins that touch a given species and divide this by the total number of pins dropped x 100
What are transects used to investigate?
The distribution of plant populations
How do transects work?
- can figure out how species change over an area
Three types of transect: - line, a tape measure is placed along the transect and the species that touch the tape measure are recorded
- belt transect, data is collected along the transect using frame quadrats placed next to each other
- interrupted transects, instead of investigating them whole transect of either a line or a belt you can take measurements at intervals