Biodiversity Pt 1
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. What would you like to do?
- A group of individual organisms very similar in
- whose members are able to interbreed freely to produce fertile offspring.
- The place where an organism lives. (with a specific set of conditions and organisms living there)
- eg. rock pools, oak woodland, rainforest, freshwater ponds.
The variety of life - the range of living organisms to be found. It includes all the different plants, animals, fungi and microorganisms species worldwide, the genes they contain, and the ecosystems of which they form a part.
We can consider biodiversity at a number of levels. What are they? (3)
- Range of habitats in which different species live (difference between habitats)
- Differences between species - structural and functional differences.
- Genetic variation within the same species
Figures estimating the number of species in the Catalogue of Life are only estimates, and we cannot be sure how accurate they are because:
- We cannot be sure we have found all species on Earth
- New species are being found all the time
- Evolution and speciation are continuing
- Many species are endangered and some are becoming extinct.
Estimates of number of species there are does not in itself reflect biodiversity because:
- Biodiversity is not just a count of how many species exist.
- Do not take into account of the number of individuals in each species.
- Does not give any indication of the variation between different species, or within species.
Explain why we share so many of our genes with plants.
- Because the fundamental biochemistry of life is same for all species.
- For example, biochemistry of cell membranes, many cell organelles, respiration, protein synthesis is the same, and require similar/same proteins or enzymes.
Why do we sample a habitat?
- To identify species present and count how many individuals there are, in order to measure biodiversity.
- It is impractical to count and identify every individual in a habitat, so we select a small portion of the habitat and study it carefully, and calculate from this the estimate of the number in the whole habitat.
List 3 ways you can randomly choose the positions where random samples are taken.
- Take samples at regular distances across habitat
- Use random numbers (generated by computer or random number generator) to plot coordinates within habitat.
- Use portable global positioning system and coordinates on map to find exact position in habitat.
What does random sampling mean?
Studying a small part of the habitat and assuming it contains a representative set of species that can be applied to the whole habitat. The sample sites must be chosen at random.
If you are comparing the biodiversity of two habitats as part of the same study, what do you need to make sure you do in terms of sampling?
Make sure you take the same number of samples in each case.
Why is it important to carry out a visual survey of the habitat and not just random sampling?
- Because random sampling may miss plants that occur only infrequently. It is important to spot odd individuals that are not found in the random sampling technique.
- You should record these as present but with no abundance - only qualitative data. Do not use for statistical analysis.
What do you use to define the size of a sample area?
A quadrat (usually 1m by 1m)
How do you measure the abundance of smaller herbs and grasses that are too numerous to count?
Measure the percentage of ground cover
How can you measure the abundance of plants found within a quadrat frame?
- Use abundance scale (though not precise) give estimates of abundance. ACFOR scale etc.
- Estimate percentage cover, grids within the frame can help.
- Use a point frame to measure percentage cover, and record plants touching the needles.
When is a line transect often used?
When the terrain changes or in a large habitat.
What are the different ways of measuring biodiversity using a line transect?
- Take reading of species touching the line every metre.
- Continuous belt transect
- Interrupted belt transect (quadrat at set intervals on line)
What is the trouble with sampling animals? How is it done?
- Animals move. Also larger ones tend to hide away from you after detecting your presence.
- You can trap animals, or note presence of larger ones by careful observation, or you can observe signs left behind like droppings and markings.
List some of the ways to catch animals for sampling.
- Sweep netting and then using a pooter.
- For trees - dislodge any small animals by shaking branches and collecting them with a sheet underneath.
- Pitfall trap
- Tullgren funnel (from leaf litter)
- A light trap (for flying insects at night)
Why do we need to study habitat?
- Because it is important to maintain habitats and reduce damage we do to them.
- We can asses how much damage we do (EIA)
What is one way of considering biodiversity of a habitat?
By measuring species richness and species evenness.
What type of survey is used to estimate species richness?
- Important not only to sample, but to have a visual survey in case you have left species out.
How can you calculate population size for smaller animals per unit area?
- Use the mark-and-recapture technique C1=number captured the first time; C2=number captured second time; C3=number already marked captured again in second time.
What are some of the features of a biodiverse habitat?
- Provides place for many different species and many organisms to live.
- Small change in environment may affect one species, but small effect on whole habitat. (also complex feeding structure)
- Habitat tends to be stable and able to withstand change.
What is taxonomy?
Study of the principles of classification. Means the study of differences between species.
What is phylogeny?
Study of the evolutionary relationships between organisms.
What is biological classification?
- Process of sorting living things into groups. There are natural and artificial classification.
- Natural does this by grouping things according to how closely related they are - reflects evolutionary relationships.
- Artificial - grouped for our convenience (eg. according to colour of flower)
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