18. Biodiversity, Classification and Conservation Flashcards
Define ‘ecosystem’.
Relatively self-contained, interacting community of organisms and the environment in which they live / with which they interact. Includes the chemical and physical conditions. ‘Relative’ because organisms in different ecosystems may interact.
Define ‘community’.
Association of populations of two or more different species occupying the same geographical area at the same time.
Define ‘habitat’.
The place where a species lives within the ecosystem.
Define ‘niche’.
The role of an organism in its ecosystem. Interactions with physical environment and other species. Organisms require resources from their environment and have adaptations to obtain them.
Define ‘biodiversity’.
The degree of variation of life forms in an ecosystem. Considered at three levels:
- variation in ecosystems/habitats
- number of species and relative abundance
- genetic variation within each species.
Define ‘endemic species’.
Only found in specific areas and no one else.
Define ‘species diversity’.
Takes species richness (number of species in a community) and evenness of species abundance into account. More species = more even distribution = more diversity = more stability. Eg. coral reefs have many ecological niches.
Define ‘genetic diversity’.
The diversity of alleles within the genes in the genome of a species. Assessed by finding the proportion of genes with different alleles and how many alleles there are.
Why is genetic diversity important?
Adaptation due to different conditions - allows stability when biotic and abiotic factors change.
Describe the ‘collecting and listing’ method of assessing species diversity.
Collect organisms (eg. using pooter to collect small organisms) and identify using dichotomous keys. Assess the distribution and abundance of the species.
Describe ‘sampling’.
Cannot count all animals unless the area is small or the organisms are very large. Sampling estimates the total numbers in the area, and can be systematic or random (used when an area looks uniform / no clear distribution pattern).
Define ‘quadrat’ in random sampling.
Square frame marking off one area of ground/water where species and their abundance can be recorded.
How does random sampling work?
Done to avoid bias. Mark an area with measuring tapes, use a random number generator for coordinates of sampling points in relation to the tapes.
Define ‘species frequency’ and ‘species density’ in random sampling.
Measure of the chance of a particular species being found in any one quadrat.
- (quadrats with species present / total quadrats) x 100
Measure of the number of individuals per unit area.
- number of individuals / total area of quadrats
How do you estimate % cover when it is not possible to count individuals?
Split a 1m x 1m area into 100 squares use this to estimate % area covered. If the individual percentages don’t add to 100, there may be bare ground - if they exceed 100, there may be species overlap.
Alt: use Braun-Blanquet scale.
Describe the ‘mark-release-recapture’ technique of estimating numbers of mobile animals.
Catch as many as possible and mark them.
Count them, then release. Let them mix randomly with the remaining population.
Catch a new large sample and find the ratio between marked and unmarked.
Eg. if 1/10 are marked, the whole population must be 10x the original.
Describe other techniques of catching / estimating numbers of mobile animals.
Catch small mammals in traps.
Insects caught by sweep netting.
Aquatic animals caught by pond nets.
Flocks of birds - count a group of ten birds, estimate how many groups there are.
What is Simpson’s Index of Diversity (D) used for?
Uses abundance to calculate species diversity in an area.
D = 1 - (Σ (n/N)^2)
- n = total number in a particular species
- N = total number in all species
- 0 = no diversity, 1 = infinite.
What are the advantages and limitations of Simpson’s Index?
- no need to identify species using scientific names, can be done using appearance
- must consider that species have various phenotypic forms
- communities and organisms must be similar
When should systematic sampling be used?
Specific areas eg. where physical conditions change. Randomly select a starting point in the area and use a transect.
Define ‘transect’.
Measuring tape in a straight line across the desired area, count the samples present along the line.
- line: record identity of organisms touching the line at intervals, qualitative data presented in a drawing.
- belt: using quadrats instead, data presented as bar chart or kite diagram.
What are correlations and when are they used?
Finding association between two species / species and abiotic factor. Found by drawing a scatter graph, or calculating correlation coefficient r. A value of 1 indicates the strongest, linear correlation.
Outline the differences between Pearson’s linear correlation and Spearman’s rank correlation.
Pearson’s:
- normally distributed data, quantitative
- linear correlation is possible
Spearman’s:
- no clear normal distribution, quantitative
- correlation but not linear
- rank the data for each variable and assess the difference between ranks.
How is Spearman’s rank correlation calculated?
Form a null hypothesis (no correlation).
Draw scatter graph to see if correlation is present.
Calculate r using:
r = 1 - (6 x ΣD^2) / (n^3 - n)
- n = number of pairs
- D = difference between each ranked pair within
quadrats.
Decide whether null hypothesis or alternative hypothesis is used.
- critical values at 0.05 probability - lower n = larger r.
How is Pearson’s linear correlation calculated?
Check if relationship is linear using a scatter graph.
Calculate r using:
r = (Σxy - nx̄ȳ) / (nSxSy)
- x = number of A in quadrat
- y = number of B in quadrat
- n = number of readings
- s = standard deviation
Standard deviation:
s = sq root ( (Σ(x - x̄)^2) / (n-1) )What is the hierarchy of the taxa used in classification?
D K P C O F G S
What are the three domains, and why are there three rather than two?
Used to be two - prokaryotes and eukaryotes.
- Extremophiles live in harsh environments, and their genes coding for rRNA are more like those in eukaryotes.
- Some produce methane, some cannot survive in oxygen, some have unusual enzymes.
Gave rise to three domains: Eukarya, Bacteria and Archaea (more in common with eukaryotes, diverged later than from bacteria).
Describe the characteristics of Domain Bacteria.
Prokaryotic, vary in size from largest virus -> smallest unicellular eukaryote.
- circular DNA, no histone proteins, exists as chromosome
- plasmids, 70S ribosomes
- no membrane-bound organelles
- peptidoglycan cell wall
- divide by binary fission
- unicellular or groups of small cells
- avg. diameter 0.5 - 5 μm
