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Summary Biodiversity classification and conservation
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Biology A level revision notes on Biodiversity classification and conservation
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Biodiversity, Classification and ConservationSpecies: a group of organisms with similar morphology and physiology, which can breed
together to produce fertile offspring and are reproductively isolated from other species
Ecosystem: a relatively self-contained, interacting community of organisms, and the
environment in which they live and which they interact
Niche: the role of an organism in an ecosystem
Biodiversity
This can be defined as the degree of variation of life forms in an ecosystem and includes 3
different levels:
The variation in ecosystems or habitats
The number of different species in the ecosystem and their relative abundance
The genetic variation within each species
The number of species in a community is known as species richness. Species diversity takes this
into account but also includes the evenness of the abundance of different species. The more
species there are and the more evenly distributed, the greater the species diversity.
Genetic diversity is the diversity of alleles within the genes and the genome of a single species.
All individuals of a species have the same genes but may have different alleles. Genetic
diversity within a species can be measured by finding out what proportion of genes have
different alleles and how many alleles there are per gene. There is also genetic diversity within
a population and this allows them to adapt to changes of abiotic and biotic factors eg.
Competition with other species or a change in temperature.
Sampling
Samples are taken to make an estimate of the total numbers of species in an area as it is very
hard to measure species in the entire area. If there is no clear pattern to way the species are
distributed then random sampling is best.
Quadrats are square frames that marks off an area of ground where you can identify the
different species present and measure their abundance. Samples must be taken randomly to
avoid any bias so a random number generator is best to use. Percentage cover can also be
calculated by using a quadrat divided into smaller squares.
Mark-release-recapture can measure population size of mobile organisms:
Collect as many organisms of a species
Each one is marked in a way that it does not affect its survival
These are counted and released back to their environment
Once enough time has passed, another sample is collected
Proportion of marked to unmarked organisms is calculated and used to estimate the
total number in the population
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