Biodiversity Flashcards
What is habitat diversity?
The number of different habitats found within an area
How does habitat diversity affect overall diversity?
The greater the habitat diversity the greater the overall diversity
Give some examples of habitats.
Meadow, woodland, stream, sand dune
What is species richness?
Species richness refers to the number of different species living in a given area
What is genetic biodiversity?
Refers to the variety of genes that make up a species
What is species evenness?
A comparison of the number of individuals of each species living within a community
How does greater genetic biodiversity affect a species?
It allows for greater adaptation to a changing environment and is more likely to result in individuals which are resistant to disease.
What is sampling?
Taking measurements of a limited number of organisms within a particular area.
What is meant by random sampling?
Selecting individuals by chance.
How to carry out random sampling.
-Mark out a grid on the grass using two tape measures at right angles to each other
-Use random numbers to determine the x and y coordinate on your grid
-Take a sample at each of the coordinate pairs generated.
Describe and explain the different types of non random sampling.
Opportunistic - using organisms that are conveniently available. This is the weakest form of sampling as it may not be representative of the whole population.
Stratified - some populations can be divided into strata based on certain characteristics. A random sample can then be taken from these strata proportional to its size.
Systematic - sampling different areas separately. Often carried out on a line belt or transect.
What is a line transect?
Mark a line along the ground between two poles and take samples at specified points.
What is a belt transect?
Two parallel lines are marked and samples are taken between the two lines.
Give an example of sampling bias.
You may choose to sample an area which has more flowers because it looks more interesting
Give some example of sampling methods with animals.
Pooter - by sucking on a mouthpiece insects are drawn into the chamber.
Sweep nets
Pitfall traps - dig a hole in the ground that insects can fall into and cover with leaves to prevent rainwater getting in
Tree beating - A white cloth is placed under a tree and the tree is shaken or beaten to dislodge insects
What is the difference between point and frame quadrats?
A point quadrat has a horizontal bar with vertical pins going through which can be pushed down and the species of plant the pin touches is recorded. A frame quadrat is a square frame divided into sections. The type and number of species within each section is recorded.
How do you measure species richness?
After sampling, compile a list of each species identified. The total number of species can then be calculated.
How to use a quadrat to measure diversity.
Density - absolute measure. Count the number of individual large plants of a species within a 1m by 1m section of the quadrat.
Frequency - estimate. Count the number of squares a species is present in.
Percentage cover - estimate by eye the percentage of the quadrat a certain species occupies.
How to calculate biodiversity.
Simpsons index = 1- sum of (n/N)^2
where n = total number of organisms of a particular species
N = total number of organisms of all species
What do the results of simpsons index mean?
A value closer to 0 means no diversity and a value closer to 1 means infinite diversity
Name some factors that positively effect genetic biodiversity.
- Mutations in the DNA of some organisms creating new alleles.
- Interbreeding between different populations
Name some factors that negatively effect genetic biodiversity.
- selective breeding e.g pedigree dogs or human food crops
- captive breeding programmes
- artificial cloning
- natural selection
- genetic bottlenecks - where few individuals within a population survive an event reducing the gene pool
What influence can humans have on biodiversity?
Due to population growth humans do many things that negatively impact biodiversity:
- Deforestation = reduces species diversity especially if only one type of tree is being targeted. Reduces the number of animal species around as it destroys habitats
- Agriculture = removal of hedgerows reduces number of plant species present and removes some habitats reducing the number of animals. Pesticides reduce species diversity by killing pests. MONOCULTURE = only planting one crop greatly reduces biodiversity with other plants and also animals.
- Climate Change = melting of polar ice caps could lead to extinction of some of the species that live there. It could also lead to rising sea levels which will flood the low lying land reducing the biodiversity.
What does polymorphic mean?
Multiple alleles exist for one gene.
