M4 C11:biodiversity Flashcards
what is biodiversity?
the number of different ecosystems and habitats in an area, the number of species within the ecosystems and the genetic variation
what is a habitat?
where an organism lives
what is a species?
a group of organisms of common ancestry that interbreed to give rise to fertile offspring
what are the 3 levels of biodiversity?
habitat
species
genetic
what is habitat biodiversity?
where species inhabit included both abiotic and biotic factors. number of different habitats in area
examples of abiotic factors?
air, soil, temperature, light, water
examples of biotic factors?
food webs, competition, predators,
what is species biodiversity?
species richness- no of dif species
species evenness- no of each species
for example there may be a high species richness but a low species evenness if the area is dominated by 1 species more than the rest
what is genetic biodiversity?
genetic diversity- variation of alleles within species.
this allows better adaptation if species to a changing environment. this is often limited in smaller populations due to inbreeding
what is sampling?
taking measurements of a limited no of organisms present in a specific area
what must sampling be representative of?
size or area of transect
repeat measurements
accounting for different times of the year
what 3 things do quadrats measure?
species frequency- % of quadrats with the species
species density- no of individual organism in quadrat
percentage cover- % of area of quadrat with the organism
what is random sampling?
taken to avoid any bias, random generators are used to determine coordinates for sampling, each site has an equal chance of being chosen
what is opportunistic sampling?
most biased, researcher makes sampling decisions based on prior knowledge or during process. may use favoruable areas
what is stratified sampling?
habitat divided into areas which appear different and each area sampled differently to include all different areas
what is systematic sampling?
taken at fixed intervals across the habitat
either using a;
belt transect-provides info on quadrats along transect line
interrupted belt transect- records at set intervals along transect line
line transect- records species touching transect line
evaluate random sampling?
least bias as every site has an equal chance of being used
time consuming and may only cover 1 area
evaluate opportunistic sampling?
more chances of species being present and is easier and quicker
most bias- observer bias
evaluate stratified sampling?
takes all areas into account
may be over representative and biased as lots of area is covered
evaluate systematic sampling?
more representative
some species may be missed if not close to transect line
how else can we sample animals?
beating tray
pooter- suck animals into a glass
sweep net
pond net
pitfall trap- trap covered with lid to keep out rain
what is the capture- mark- release- recapture method to sample animals?
catch fist sample and mark them
release them back into environment
after a certain time catch another sample, some in this may be marked from the first sample
smaller no of marked individuals= larger population
how do we estimate population by the Lincoln index?
population size= sample 1 x sample 2 divided by no of marked in sample 2