11 Biodiversity Flashcards
a)Define biodiversity
Variety of living organisms present in an area. It includes plants, animals, fungi and other living things
a)Define species
A group of individual organisms very similar in appearance, anatomy, physiology, biochemistry, and genetics, whose members are able to interbreed freely to produce fertile offspring
a)Define habitat
The area in which an organism lives
b)Explain how biodiversity may be considerd at different levels: habitat, species and genetic
Habitat: its possible to measure the number of different types of habitat within an area. This forms a biodiversity
Species: its possible to measure either the number of different species in an area(species richness), or the relative number of individuals within each species(species evenness). These are both forms of biodiversity
Genetic: its possible to measure the amount of genetic variation within a single species. This is a form of biodiversity
c)Importance of sampling in measuring the biodiversity of a habitat
A sample is a representative group of organisms that are selected from a population. When measuring the biodiversity of a habitat, it’s usually impractical to count every single individual organism in that habitat
-sampling allows you to produce an estimate of each species’ population size without actually counting all the individuals
Species richness
Species evenness
SR: The number of different species in an area
The higher the number of species= greater the richness
SE: Measure of the relative abundance of each specie in an area
d)Describe how random samples can be taken when measuring biodiversity
- Random sampling is sampling in which the observer does not decide when or where to take measurements.
- This is important because if the observer chose where to take measurements, then the sample would be biased
1) one way of conducting random sampling is to place quadrats at random points in the area
2) Two tape measures are laid on the ground at right-angles to each other in order to create a pair of axes.
3) Computer is then used to generate pairs of random numbers.
4) The pairs are coordinate pairs.
5) Quadrats are places at these coordinates
e)How is species richness and species evenness measured in a habitat
- there are 2 components of species-level biodiversity
- species richness: number of species present in an area
- species evenness: measure of the relative numbers of individuals in each species
- can both be measured by taking random samples from the habitat. The observer should sample many times and then calculate the mean. Samples should be taken at different times of the day and different times of the year and in a number of locations within the study area in order to get an accurate picture of species richness and evenness in the area. The techniques is random sampling can be used to randomly select areas to sample.
e)How to measure animal richness and animal species in a habitat
-Sweep nets can be used to sample insects in a habitat. If the insects are in a tree then a better approach is to place a white sheet under the tree and knock a branch with a stick, so that the insects fall out onto the branch. At night, a light source can be used to attract insects to a white sheet. It is important to standardise the sampling procedure, and to ensure that the insects do not escape before being identified. Insects can be marked to prevent them from being counted twice.
Pitfall traps can be used to sample small animals, for example in leaf litter.
Mark-release-recapture can be used to estimate the population size of any animal. It uses the following equation:
*Population = (no. in sample 1 x no. in sample 2) / no. retrapped in sample
e)How to measure plants, fungi richness and evenness in a habitat
Plants, fungi and other non moving organisms can be sampled using randomly placed quadrats (as described previously . For organisms that cover large areas of ground, it is often more useful to measure percentage cover than count the number of individuals.
-Point frames can be used in combination with quadrats in order to take more accurate measurements of percentage cover. For less frequent plants it is often useful to either count all of the individuals, or collect qualitative data using the ACFOR scale (record whether each species is Abundant, Common, Frequent, Occasional, or Rare).
Transects can be used to measure species richness and evenness along a line. In an interrupted transect the quadrats are spaced out equally along the line. In a continuous transect the quadrats are placed continuously along the line.
f) Use Simpson’s Index of Diversity (D) to calculate the biodiversity of a habitat, using the formula D = 1 (Σ(n/N)2)
Simpson’s Index of Diversity (D) can be calculated as follows: D = 1 (Σ(n/N)2), where n = the number of individuals of a particular species,
and N = the total number of individuals of all species (the sum of all the n values).
Outline the significance of both high and low values of Simpson’s Index of Diversity(D)
- SID takes into account both species richness and species evenness
- SID values range from 0-1
- high value of SID indicates a high species richness and high species evenness and therefore a high level of biodiversity
- Low value of SID indicates a low species richness and low species evenness, and therefore a low level to lose species
h) Discuss current estimates of global biodiversity
- The total number of species that exist today is probably much larger than the number of species identified so far. This is likely to be the case for a number of reasons: not all areas have been explored yet; it is difficult to see species that are small, microscopic, nocturnal or camouflaged; sampling may miss rare species; individuals of two different species could be mistakenly identified as a single species; and the concept of a species is difficult to define.
- Various estimates have been produced for the total number of species that exist today. However it is difficult to judge the accuracy of these estimates because: we can never be sure that we have found all of the species; new species are constantly being found; evolution and speciation are ongoing; and
