Chapter 11 - Biodiversity
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Species diversity:
number of individuals of each species
Habitat diversity:
Number of habitats in a location
genetic diversity:
variety of alleles in a population
population:
number of individuals of a single species
community:
number of individuals of all species
What is random sampling?
Is used to test abundance only e.g. how many individuals
Process of how to use a quadrat:
1) lay tape measure at right angles 2) use a random number generator to generate two coordinates 3) place quadrat at coordinates (take sample) 4) use a key to identify each individual 5) count number of species or % cover 6) repeat at least 15 times 7) calculate mean per quadrat 8) estimate population
How to estimate population:
total are of habitat divided by area of one habitat multiplied by mean per quadrat
What is systemetic sampling?
Used to measure abundance and distribution of species - usually in response to an environmental gradient TRANSECTS
How to do systemetic sampling:
1) place quadrats/samples at regular intervals along the gradient 2) use a key to identify the individuals 3) count abundance or measure % cover 4) repeat transect parallel to original
What is stratified sampling?
• used when investigating two or more groups/strata e.g. population of location A and location B or time (day and night) OR different habitats at the same location e.g. field versus grass at back of school
What makes up species biodiversity?
species richness and species evenness
Species richness:
number of species in a habitat (counts as 1 if species is present, regardless of abundance/% cover/number
Species evenness:
number of individuals of each species present in the community
What is species biodiversity measured and compared using?
a biodiversity index
What is the Simpsons Index?
Simpson’s Index of Diversity is a mathematical formula used to measure the biodiversity of a habitat. It evaluates not just the number of different species present (species richness), but also how evenly populated those species are (species evenness)
What does genetic diversity refer to?
• individual species/populations. have the same genes (to reproduce and have fertile offspring) BUT individuals can have different alleles • differences are due to changes in DNA base sequences
factors effecting genetic biodiversity:
• mutations, migration, founder effect, genetic bottle neck
Mutation:
change in base sequence
Migration:
immigration introduces new alleles to reduce inbreeding
Founder effect:
there are few individuals that colonise a new location - founder pop contains a sub-sample of the original pop - lower genetic diversity, meaning descendants are also limited as alleles are inherited e.g. Pilgrim Fathers, Amish, Galapagos finches, tortoise etc
Genetic bottleneck:
A dramatic loss of individuals leaves few survivors - often due to natural disasters could be because of human ‘natural disasters’ too - HUNTING
Sweep net sampling:
• used to collect flying insects • control: height above ground, number of sweeps, open area & mesh size, and arc of sweep
Kick net sampling:
• used to sample river/stream beds • kick riverbed to suspend organisms and sediment then river flow washes organisms into net • control: distance between kick and net, number and intensity of kicks