Flashcards in Mod 4 Chap 11: Biodiversity Deck (44)
Describe how biodiversity can be studied / measured at different levels.
- closer a region is to equator = more biodiversity
- biodiversity plays important role in conservation, informs scientists of species present
- this provides baseline for level of biodiversity in an area
- so, effect of any changes to environment can be measured from this info (e.g. effect of human activity, disease, climate change etc)
- Biodiversity can be studied at diff levels, of:
Habitat biodiversity, Species biodiversity, and Genetic biodiversity
Describe the study of habitat biodiversity, and give examples of habitats.
- reefers to no. of diff habitats found in an area
- each habitat can support a no. of diff species, so, greater the habitat biodiversity = greater the species biodiversity in that area
Examples: meadow, woodland, streams, wild grassland
Describe the study of species biodiversity, and define species.
Species: a group of similar organisms able to reproduce to give fertile offspring.
Two components of species biodiversity:
- species richness: no. of diff species living in a particular area
- species evenness: a comparison of no.'s of individuals of each species living in a community
Describe the study of genetic biodiversity.
- refers to variety of genes that make up a species
- many of genes making up organisms are same for all individuals in a species, but, for many genes, diff versions (alleles) exist
- this then leads to genetic biodiversity in a species which can mean quite diff characteristics are exhibited
- greater genetic biodiversity in a species = better adaption to changing environment, + is more likely to result in disease-resistant individuals
- when population of an organism has a large 'gene pool', it has greater chance of surviving than a pop w/ limited genetic variability
- so genetic biodiversity = important
Define biodiversity, community and gene pool.
Biodiversity: The variety of living organisms present in an area
Community: All the populations of living organisms in a particular habitat
Gene pool: The variety of genetics of the individuals in a population (so large gene pool = significantly varying genetics in individuals of a pop)
Describe how genetic biodiversity can be assessed.
- measuring polymorphism
- polymorphic genes have more than one allele
- but most genes are monomorphic (only have a single allele that exists for them)
- this ensures basic structure of individuals in a species remains consistent
- proportion of polymorphic genes can be measured w/ formula:
Proportion of polymorphic gene loci = no. of polymorphic gene loci / total no. of loci
(Where locus of a gene refers to position of a gene on a chromosome)
- greater proportion of polymorphic gene loci = greater genetic biodiversity in a population
Describe the importance of sampling, and define sampling.
Sampling: taking measurements of a limited no. of individual organisms present in a particular area.
- can be used to estimate no. of organisms in an area, without counting them all. (No. of individuals of a species present in an area = abundance of the organism)
- can also be used to measure a particular characteristic of an organism
- after measuring sample, can use results to make generalisations / estimates about no. of organisms, distribution of species, or measured characteristic throughout entire habitat
- sampling can be done in two ways: random + non random
Describe random sampling.
- means selecting individuals by chance
- each individual in pop has equal likelihood of selection
- random number tables / computers can be used to decide, you have no involvement in the choice of what is studied
Describe a practical investigation into collecting a random sample in the field.
E.g. Taking a random sample at a grass verge:
- mark a grid on grass w/ two tape measures at right angles
- use random numbers to determine x and y coordinates on grid
- take sample at each of coordinate pairs generated
Describe non random sampling.
- alternative method where samples is not chosen at random
- divided into three main Non Random sampling techniques:
Opportunistic, Stratified, Systematic
Describe Opportunistic Non Random Sampling.
- weakest form of sampling as may not be representative of population
- uses organisms that are conveniently available at the time
Describe Stratified Non Random Sampling.
- Some populations can be divided into a no. of strata (subgroups) based on a particular characteristic
- random sample then taken from each strata proportional to its size
Describe Systematic Non Random Sampling, and how it is carried out.
- when diff areas in an overall habitat are identified + then sampled separately
- often carried out using a line / belt transect
Line transect: marking a line between 2 placed poles (one at one end of chosen site + one at other), then taking samples at specified points between two points, e.g. all organisms that touch the line
Belt transect: provides more information. Two parallel lines are marked in ground, + samples are taken of area between two lines (e.g. by placing quadrants)
Describe a practical investigation into collecting a non random sample in the field.
E.g. With stratified, on a heathland
- heathland may have patches of gorse on it
- so Heath + gorse areas would be sampled separately according to how much of each there was in the habitat
Describe the issues with the reliability of sampling.
- a sample = never entirely representative of organisms present in a habitat
- this may be due to:
Describe Sampling Bias as an issue with the reliability of sampling.
- selection process may be biased, may be by accident / on deliberate
- effects of sampling bias can be reduced using random sampling (as human involvement in choosing sample is removed)
Describe Chance as an issue with the reliability of sampling.
- organisms selected may, by chance, not be representative of whole pop
- chance can never be completely removed from process, but it's effect can be minimised w/ a large sample size
- as, greater no. of individuals studied = lower probability that chance will influence result
- so, larger sample size = more reliable result
Describe some methods used to collect living animals to sample.
- Pooter: catches small insects, person sucks on mouthpiece + insect drawn into holding chamber via inlet tube, filter before mouthpiece stops insect being sucked into person's mouth
- Sweep Nets: catch insects in areas of long grass
- Pitfall Traps: catch small crawling invertebrates, a deep hole in ground covered w/ roof structure to prevent filling w/ rain water, left overnight to collect nocturnal species too
- Tullgren Funnel: device to cope t small animals from sample of soil / leaf litter, sample placed on sieve fixed across wide end of funnel, light bulb above funnel to dry + warm sample, so animals move down through sieve into funnel + collecting dish, (which may contain water / alcohol to prevent escape)
- White Sheets: placed on ground below bushes branches, bush shaken so invertebrates fall onto white sheet, can then remove from sheet w/ pooter
- Light Traps: collects insects by confusing them + intercepting chosen flight path, most commonly effective for night-flying insects
Describe some other methods used to sample plants.
Quadrats, two main types:
- Point quadrat: frame w/ a horizontal bar, long pins pushes through bar at set intervals to reach ground, each species of plant pin touches is recorded
- Frame quadrat: square frame divided into a grid of equal sections. Type + no. of species in each section of quadrat is recorded
Describe how quadrats can be used to collect the most valid representative sample of an area.
- sample = most valid + representative when quadrats used following a random sampling technique
- but, can be placed systematically to study how presence + distribution of organisms across an area of land varies
Describe how to measure species richness.
- identification keys used to accurately identify all species present in a habitat (I.e. images to identify them / questions to classify them into particular species, based on identifiable characteristics they have)
- a list should be complied of each species identified
- total no. of species can then be calculated
Describe how to measure species evenness.
- take random samples of a habitat
- count no. of individuals of each diff species
Describe the overall general method to estimate biodiversity using samples.
- choose a site to sample (via random / non random)
- record no. of diff species / count no. of individuals of each species
- repeat process; take as many samples as possible to give better indication of whole habitat
- estimate no. of individuals for whole habitat by calculating mean for data collected in each sample + multiplying it by size of whole habitat
Describe how to calculate the biodiversity of a habitat using Simpsons index of diversity (D).
- Simpsons index if diversity (D) = better measure of biodiversity than simple way of just species richness, as takes into account both species richness + evenness
D = 1 - ☪ (n / N)^2
☪ (see notes for actual symbol) = sum of (total)
N = total no. of organisms of all species
n = total no. of organisms of a particular species
Simpsons index always results in values between 0 and 1. Higher the value = more diverse the habitat.
Describe the factors affecting genetic biodiversity, that cause it to increase.
To increase genetic biodiversity, no. of possible alleles in a pop must also increase, can happen through:
- mutations in DNA
- interbreeding between diff pops, alleles are then transferred between two pops, knows as 'gene flow'
Describe the factors affecting genetic biodiversity, that cause it to decrease.
To decrease genetic biodiversity, no. of possible alleles in a pop must also decrease, can happen through:
- selective breeding / artificial selection
- captive breeding programmes in zoos + conservation centres
- rare breeds (where selective breeding has been used to produce a breed of domestic animal / plant w/ characteristics that have become less popular, so numbers of this breed fall
- artificial cloning / asexual reproduction
- natural selection - only fittest / best adapted survive
- genetic bottlenecks - where few individuals in a pop survive an event / change, reducing gene pool
- the founder effect - a small no. of individuals create a new colony
Describe how the grand scale factor of human population growth affects biodiversity in general.
- linked to medical improvements, hygiene, housing + infrastructure so people live longer too
- severely disrupting ecology of areas for space for building + farming to support increasing pop, decreasing biodiversity. Doing this by:
- agriculture: more + more land farmed to feed growing pop, so
= masses of land cleared + monoculture (planting a
- climate change: release of CO2 + pollutants into atmosphere from
burning fossil fuels = increasing global temp,
decreasing biodiversity by killing some organisms
Describe how the factor of agriculture affects biodiversity in general.
Affects biodiversity by:
- deforestation: increases land for growing crops / rearing animals, so can increase biodiversity, but decreasing biodiversity of trees + plants at same time
- removal of hedgerows: to use large machinery for harvesting crops, reducing no. of plant species + habitats + so biodiversity in an area
- chemicals: e.g. Pesticides, kills pests that would eat crops, reducing species diversity directly, + also indirectly by destroying a food source for other organisms
- chemicals: e.g. herbicides, kill weeds as they compete w/ cultivated plants for light / minerals / water, = reduces plant diversity directly, + also maybe animal diversity indirectly by removal of a food source
- monoculture: lowers biodiversity as only one species of plant present, + lowers animals diversity too as only few species will be supported by one plant type
Describe how the factor of deforestation affects biodiversity in general.
- can occur naturally, but most is deliberate result of human action
- some forest areas indirectly destroy by humans through acid rain (result of pollutants in atmosphere)
- directly reduces no. of trees in an area
- species diversity = reduced if only a specific tree type is felled
- destroy habitats on animal species, reducing no. of animal species present in an area, so this starts a chain of events killing other species reliant on that's species for food if they are killed
- forces animals to migrate to other areas for survival, may increase biodiversity if neighbouring areas