Biodiversity- sampling and genetic biodiversity Flashcards
what is biodiversity?
the variety of living organisms present in an area. It is essential for maintaining a balanced ecosystem. They provides us food, shelter. Generally places near the equator have a higher biodiversity.
what types of biodiversity can be studied?
- habitat biodiversity
- species biodiversity
- genetic biodiversity
Describe habitat biodiversity
number of different habitats found in an area. Greater habitat biodiversity, greater species biodiversity.
what are the two different components of species diversity?
- species richness
- species evenness
What is species richness?
the number of different species living in a particular area
What is species evenness?
a comparison of the numbers of individuals of each species living in a community.(The community is all the populations living organisms in a particular habitat).
Describe genetic biodiversity?
refers to the variety of genes that make up a species. Genetic biodiversity in a species is due to the different alleles which exist in genes. E.g cot colour and length in dogs
Why is greater genetic biodiversity important?
better adaptations to a changing environment, more likely to result in individuals who are resistant to disease
what is sampling?
taking measurements of a limited number of individual organisms present in a particular area. Used to estimate the number of organisms in an area without having to count them all
types of sampling?
random and non-random
Describe random sampling?
means selecting individuals by chance. Each individual in a population has an equal likelihood of selection. Random number generators can be used
Describe steps for random sampling
- mark out a grid using two tape measures placed at right angles to each other
- generate random x and y coordinates
- take a sample at each random coordinate generated
What three methods are non-random sampling divided into?
opportunistic, stratified, systemic
What is opportunistic sampling?
weakest form of sampling as it may not be representative of the population. This sampling uses organisms that are conveniently available.
What is stratified sampling?
some populations can be divided into a number of strata (sub-groups) based on a particular characteristic. A random sample is the taken from each strata proportional to its size
What is systemic sampling?
different areas within an overall habitat are identified, which are then sampled separately. Often uses a line or belt transect
What is the difference between a line and belt transect?
- a line transect involves marking a line between two poles and taking samples at specified points.This can describe all organisms which touch the line or distances of samples from the line.
- a belt transect provides more information (more accurate), two parallel lines are marked and samples are taken between the two lines
Why is a sample never entirely representative of the organisms present in a habitat? and how can this be reduced?
- sampling bias: selection process may be bias which could be accidental or deliberate. This can be reduced by removing human involvement in choosing random coordinates.
- chance, this can be minimised by taking a large sample size
how is a pooter used to sample animals?
catches small insects by sucking on a mouth piece. Insects are drawn into the holding chamber via the inlet tube. A filter prevents suction to the mouth
How are sweep nets used to sample animals?
used to catch insects in areas of long grass
How are pitfall traps used to sample animals?
used to catch small, crawling invertebrates. A hole is dug into the ground which insects fall into. It must be deep enough so they can’t crawl out and covered with a roof. Should be left overnight so nocturnal species are also sampled.
How is tree beating used to sample animals?
samples invertebrates living in a tree or bush. A large white cloth is stretched under the tree. The tree is shaken or beaten to dislodge invertebrates where they are collected and studied
How is kick sampling used to sample animals?
used to study organisms living in a river. The river bank and bed is kicked for a period of time to disturb the substrate. A net is held just downstream for a set period of time to capture any organisms
When are quadrats used for sampling?
used to sample plants and slow moving animals
What are the two main types of quadrat?
point quadrat and frame quadrat
Describe point quadrat?
frame contains horizontal bar. At set intervals along the bar, log pins are pushed through the bar to reach the ground. Each species of plant the pin touches is recorded.
Describe frame quadrat?
consists of square frame divided into a grid of equal sections. Species within each section of the quadrat is recorded
What are the three main ways plants can be sampled using a frame quadrat?
- Density
- Frequency
- percentage cover
Describe how to measure plant abundance using density?
count number of plant species using 1m squared quadrat. This is an absolute measure, not estimate.
Describe how to measure plant abundance using frequency?
this is used when individual species are hard to count like grass. Using the small grids in a quadrat, count the number of squares a particular species is present in. It is an estimate
Describe how to measure plant abundance using percentage cover?
this is used for speed as lots of data can be collected quickly. It is useful when a species is difficult to count. It is an estimate by the eye of the area within a quadrat.
how do you increase reliability?
sample more areas and calculate a mean
What is capture- mark- release-recapture?
technique to estimate population size of animals.It involves capturing as many individuals of species in an area as possible. The organisms are marked and released back to redistribute, another sample is collected. Number of marked and unmarked individuals are compared. The greater the number of marked, the smaller the population
Many abiotic factors can be measured using a sensor. Why is this advantageous?
- rapid changes can be detected
- human error is reduced
- high precision
- data can be stored and tracked on computer
What is an abiotic factor?
non-living conditions in a habitat
Why is monitoring biodiversity important?
for successful conservation and environmental management
Why should you not measure biodiversity by counting number of species present?
doesn’t take in to account number of individuals present.
How should you measure biodiversity?
using Simpsons diversity index. It takes into account species richness and evenness.
what is Simpsons diversity index?
D=1-z(n/N)squared
z(looks like)-sum of (total)
N-total number of organisms of all species
n-total number of organisms of a particular species
-simpsons diversity index is always between 0 and 1, higher number, higher diversity
What does low biodiversity tell us about the habitat?
- few successful species
- stressful/extreme environment
- species that live in habitat have very specific adaptations to environment
- simple food webs
- major effects on the ecosystem
What does high biodiversity tell us about the habitat?
- a large number of successful species
- not stressful environment
- species that live in habitat have few specific adaptations to environment
- complex food web
- small effects on ecosystem
How is genetic variation created within a species?
variation of alleles within a gene. The more alleles in a population the more genetically diverse
Why are species with greater genetic diversity less likely to become extinct?
more likely to carry an advantageous allele which can help them adapt and survive in altered conditions
what factors cause genetic biodiversity in a population to increase(increased alleles)?
- mutation (new allele)
- interbreeding between different populations, alleles are transferred known as gene flow
what factors cause genetic biodiversity to decrease(decreased alleles)?
- selective breeding (artificial selection)
- captive breeding programs
- rare breeds
- artificial cloning
- natural selection
- genetic bottlenecks
- the founder effect
- genetic drift
what is selective breeding?
where only few individuals with advantageous characteristics are bred
explain captive breeding programs?
in zoos or conservation centres where a small number of captive individuals of a species is available for breeding usually to prevent extinction
explain rare breeds
?
explain artificial cloning
asexual reproduction, e.g using cutting from a plant
explain natural selection
species will evolve to primarily contain the advantageous alleles which code for advantageous characteristics. Over time coding for less advantageous alleles will be lost.
explain genetic bottlenecks
where few individuals survive from an event of change, reducing the ‘gene pool’. Only the alleles of the survivors can be passed down
explain the founder effect
where a small number of individuals create a new colony geographically isolated from the original. The gene pool is small
explain genetic drift
when a particular allele disappears from a population randomly from parent to offspring as alleles frequently vary.
how do you measure genetic biodiversity?
by measuring polymorphism
what are polymorphic genes?
gene which have more than one allelle
what are monomorphic genes?
genes where a single allele exists. Most genes are monomorphic. This ensures the basic structure of individuals in a species remains consistent
how do you measure proportion of genes which are polymorphic?(greater number, greater genetic biodiversity)
number of polymorphic gene loci / total number of loci
