4.2 Biodiversity Flashcards
what is biodiversity
the variety of living organisms in an area
what is species
a group of similar organisms able to reproduce to give fertile offspring
what is habitat
the area inhabited by a species, including physical factors (soil and temperature range) and living factors ( availability of food and presence of predators)
what would an area with high biodiversity have
lots of different species
what are the 3 different levels of biodiversity
habitat, species and genetic
what is habitat biodiversity
the number of different habitats in an area
- in general, area with higher habitat biodiversity will have higher species biodiversity
- high diversity would have many habitats, e.g. sand dunes, meadows, woodland and streams
what is species biodiversity
the number of different species and the abundance of each species in an area ( richness and evenness)
what is genetic diversity
the variation of alleles within a species (or a population of a species)
- this leads to different characteristics being exhibited within the same species, e.g. breed of dogs
- good as can better adapt for changing environment and more likely to arise in individuals resistant to disease
why are sampling techniques used
in most cases, too time-consuming to count every individual organism in a habitat, so samples of a population are taken
- estimates of whole population is then based on the samples
- also estimate particular characteristics of a population by taking averages
how would you carry out a sampling technique
1) choose area to be sampled
2) count the number of individuals of each species
3) repeat the process, taking as many samples as possible
4) use results to estimate the total number of individuals or different species in the habitat being studied
- if sampling different habitats and comparing, always use SAME sampling technique
how would you alter your sampling techniques based on the organism
- for crawling insects, use a pitfall trap (a small pit that insects can’t get out of) or a pooter (allows you to safely suck insects into a jar)
- for small organisms in soil or leaf litter, use Tullgren funnel
- for aquatic organisms, use kick sampling, where you kick bottom of stream and collect insects
- for long grass, use a sweep net
explain a random sample
- needed to avoid bias in your results
- e.g. dividing field into a grid and using random number generator to choose coordinates
why may you sometimes need to use a non-random sample
- if there is a lot of variety in the distribution of species in a habitat, and you want to make sure all the different areas have been sampled
what are the 3 types of non-random samples
SYSTEMATIC: where the samples are taken at fixed intervals, along a line, for example using quadrats placed along a transect line
OPPORTUNISTIC: where samples are chosen by the investigator, is simple to carry out but will be biased
STRATIFIED: different areas are identified and sampled separately in proportion to their part of the habitat as a whole, e.g. areas of heath and gorse would be sampled separately in a heathland depending on how much they take up of a habitat
what is species richness
the number of different species in an area, higher the number, greater the richness
- count the number of species
what is species evenness
the relative abundance of each species in an area, more similar the population size of each species, the greater the evenness
- count the number of individuals in a species
what is Simpson’s Index of Diversity
statistical test that takes into account both species richness and evenness
what will the SIoD always be
a value between 0 and 1
- the closer to 1, the more diverse an area is
what is the formula for SIoD
D = 1-(Σ(n/N)²)
n= the total number of individuals of one species
N= the total number of organisms of all species
why is it important to identify a population’s genetic diversity
- if a population has low genetic diversity
- they may not be able to adapt to a change in the environment
- and the whole population can be wiped out by a single event
- include isolated populations, e.g. those bred in captivity ( zoos, pedigree ( animal bred purely from animals of the same breed) and rare breeds (not used in large-scale farming))