4.2.4 calculating biodiversity Flashcards
define an allele
variant of a gene
define a locus
position of that gene on a chromosome
define polymorphic gene locus
locus that has 2+ alleles
what is the simpsons index of biodiversity
measure of biodiversity in a habitat
species evenness
measure of how evenly represented species are
species richness
measure of how many different species are present
what do we have to consider when measuring biodiversity
species richness & species evenness
how can species richness be measured
by counting all species present in habitat
how can species evenness be measured
must carry out quantitative survey
how can we survey the frequency of plants
- use sampling techniques eg. quadrat, transect
- record percentage cover of each plant species
–> with large plants, its better to count number of individuals per unit area
what does it mean to measure density of animals in a habitat
calculating how many animals of each species there are per unit area of a habitat
how do we measure the density of animals in a habitat of:
- larger animals
- smaller animals
- counted by observation
- counted using sampling techniques
how can the population size be calculated of:
- smaller animals
- tiny animals living in soil
- mark-and-recapture technique
- take sample of soil & sift through to find individuals & count
formula of simpsons index of biodiversity & what does each symbol stand for
pg. 260 of textbook or class booklet
what does a high value for the simpsons index indicate
highly diverse habitat
- many different species & organisms live here
- change to environment may impact 1 species & if only a small part of habitat, the total number of individuals affected is small proportion
- habitat stable & able to withstand change
what does a low value for the simpsons index indicate
habitat dominated by few species
- small change to environment which affects 1 species could damage/destroy whole habitat
- such small change could be disease/predator
what’s the genetic diversity like of isolated populations & how can it be measured
- genetic diversity is limited
- assessing it can help assess value of population as resource for conservation
- simple assessment made by looking at observable features
when is genetic diversity found
more than one allele for particular locus = variations between individuals which may be easily observable
–> means more genetic differences between gametes produced by members of population
how can genetic diversity be estimated
- by calculating number of loci in one individual that are heterozygous BUT doesn’t give good measure of value of population as genetic resource
- another measurement involves calculating percentage of loci in population which have more than 1 allele
what increases genetic diversity
having more than 2 alleles at a locus (polymorphic gene loci)
