biodiversity

what is an ecosystem?

a community of living organisms and the non-living environment they live in, and interact with.

what is a habitat?

the natural place where an organism lives.

what is a population?

a group of organisms of the same species that live in a specific area and can interbreed.

what is an environment?

the physical and chemical surroundings of an organism, including other organisms and non-living components that it interacts with.

what is a community?

a group of different species that live in the same habitat.

definition of niche?

the role that a species plays in it’s habitat.

what is a biotic factor?

a living organism or part of an ecosystem that affects other living things.

what is an abiotic factor?

a non-living part of an ecosystem that affects the way organisms and the ecosystem function.

what is species richness and how can we measure it?

• the number of species in a habitat or community

• can be measured by counting the number of different species in a habitat

• a higher species richness indicates greater diversity

what are three factors which affect biodiversity?

• human population growth

• agriculture (monoculture)

• climate change

how does human population growth affect biodiversity?

• the speed of growth of human population means there is more forest cleared so land can be used for housing and food production

  • this land would otherwise support a more diverse range of species.

• pollution and waste production also increases, putting further burdens on fragile ecosystems

how does agriculture (monoculture) affect biodiversity?

• it is more efficient to grow crops with the same requirements in terms of nutrition and ease of harvesting

  • many farms have fields set aside for growing only one type of crop e.g. wheat

• practising monoculture reduces biodiversity and can cause problems

  • monocultures with less genetic biodiversity may be less resistant to diseases.

how does climate change affect biodiversity?

• changes in global weather patterns, sea levels and temperature can lead to habitat loss, driving animals to migrate

  • in other cases, some species and populations may be completely destroyed which decreases the gene pool available for selection and evolution

• the speed of climate change can sometimes be too fast for species to adapt to new conditions, so lead to extinction

what is the equation for calculating species evenness?

species evenness = H/In S

H - shannon’s diversity index (given)

In - button on calculator

S - species richness

(species evenness ranges from 0-1)

what is species evenness?

the number of each species present within a habitat.

how do you get a random sample?

• choose an area

• randomly generate coordinates across the area (removes bias by removing human involvement)

• collect samples from random coordinates - giving us samples that are representative of the population

• repeat this several times - gives us a large sample size and minimises the effect of chance

• analyse the data that is collected - identify any relationships

what are some techniques for sampling for animals?

• pooter - samples small insects by sucking air containing the insects into a plastic container via a tube

• sweep net - samples insects in long grass or air, the net is swept in a ‘figure of eight’ motion

• pitfall trap - samples small, ground crawling animals (like spiders) by catching them in a hidden trap

• tree beating - samples the invertebrate living in a tree by shaking or beating

• kick sampling - this samples river organisms by kicking a river bank and catching organisms in a downstream net

what are line/belt transects used for?

to study the distribution of organisms in a specific area

where are the most biodiverse regions found and why?

near the equator. because there is a higher temperature and more light intensity so more photosynthesis and there a greater biodiversity.

what is species richness?

the number of different organisms present