Biodiversity, classification and conservation.
Definitions
● A species is a group of organisms with similar morphology and physiology, which can breed together to
produce fertile offspring and are reproductively isolated from other species.
● An ecosystem is a relatively self-contained, interacting community of organisms, and the environment in
which they live and with which they interact.
● A habitat describes the place where a species lives within an ecosystem. This term is often used to
mean the kind of place in which a particular species of organisms can live.
● A population is a breeding group and includes all the individuals of that species which can interbreed
with each other
● A community is made up of different species in a habitat.
● Intraspecific competition: competition for limited resources between individuals of the same species.
Opposite is interspecific competition.
● A niche is the role of an organism in an ecosystem.
● Biodiversity is the degree of variation of life forms in an ecosystem.
● Species richness is the number of species in a community.
● Genetic diversity is the diversity of alleles within the genes in the genome of a single species.
● A quadrat is a square frame that marks off an area of ground, or water, where you can identify the
different species present and/or take measurement of their abundance.
● Species frequency is a measure of the chance of a particular species being found within any quadrat.
● Species density is a measure of how many individuals there are per unit area.
● Taxonomy is the study and practice of classification.
● Extremophiles are organisms with optimal growth in environmental conditions considered extreme in that
it is challenging for a carbon-based life form with water as a solvent.
● Habitat fragmentation is when plants and animals either lose their habitats completely or their habitats
become divided into small areas
● A keystone species is a species which has a disproportionately large effect on its natural environment
relative to its abundance.
● Phylogenetic classification is classifying organisms on their basis of descent from a common ancestor.
● Cyanobacteria are a group of photosynthetic bacteria, some of which are nitrogen-fixing, that live in a
wide variety of moist soils and water either freely or in a symbiotic relationship with plants
Ecosystems
● No ecosystems are entirely self-contained as they interact with each other e.g birds migrate from one
ecosystem to another to find food and to breed.
● Ecosystems can be on different scales such as a tropical rainforest which is a complex ecosystem
whereas a sandy desert is very simple.
● An organism’s niche describes where it is, how it obtains energy and how it interacts with both its
physical environment and with other species. How they ‘fit in’ the ecosystem.
● Organisms have adaptations that help them require resources from the environment.
● Communities may remain fairly stable over a period of time or they made be in a process of gradual
change (succession)
● Succession may result in the formation of a stable community which is called a climax community.
● Experiments suggest that if two species have extremely similar niches, then one species will probably
die out when this kind of competition occurs, so that both species will not be able to coexist in the same
community.
Biodiversity
Tropical forests and coral reefs are two of the most species-rich areas on Earth.
Three levels of diversity:
✧ The variation in ecosystems or habitats
✧ The number of different species in the ecosystem and their relative abundance
✧ The genetic variation within each species.
, Endemic species are species that are only found in certain areas and nowhere else.
Species diversity
The more species there are, and the more evenly the number of organisms are distributed among the different
species, the greater the species diversity.
Ecosystems with high species diversity tend to be more stable than ones with limited diversity(more able to
resist changes).
Genetic diversity
All individuals of a species have the same genes, but they do not all have the same alleles of those genes.
The genetic differences between populations of the same species exist because populations may be adapted
slightly differently in different parts of their range. This diversity is important in order to adapt to changes in biotic
and abiotic factors such as resisting new strains of disease.
Assessing species diversity
❖ Collecting organisms and making species lists
❖ Identify and catalogue the types of organism and build a species list.
❖ Identification keys used to name the organisms that they find and the most common of these is a
dichotomous key.
❖ A pooter is a simple piece of apparatus that is used to collect these animals.
❖ Distribution: the spread of different species throughout the ecosystem.
❖ Abundance: the number of individuals of each species.
Sampling
We can take samples from the area we are interested in, and use these to make an estimate of the total
numbers of the area.
Sampling can be random or systematic. If an area looks reasonably uniform with no clear pattern to the way
species are distributed, then it is best to use random sampling.
Random sampling using quadrats.
● Avoids bias.
● Random sampling is important if the results are to be statistically analyzed.
● In practice, it is found that a quadrat with sides of 0.5 m is the best size in many terrestrial situations.
● The usual way to ensure that a sample is random is to mark out an area with measuring tapes and use a
random number generator. Use these random numbers as coordinates to determine the placing of each
quadrat. First you define the area you are going to study and use two sides of this area as axes.
Standing at the origin, you generate two random numbers and use these as coordinates for the 1 m^2
quadrats you are going to place.
● You can use your results to calculate species frequency and species density.
● When plants grow over surfaces forming a covering it is almost impossible to count individuals. Now then
you can use percentage/species cover which tells you the percentage of ground which is occupied by a
particular species. To do this:
● You use a 100cm x 100cm quadrat with wires running across it at 10cm intervals in each direction which
divides it into 100 small squares. You can then decide approximately what percentage is occupied by the
species.
● Percentage frequency tells us how common a species is, but it does not give information on how much
of the species is present once we have recorded it. Percentage cover is an additional measure of
abundance which tells us how much space a species occupies in a sample, once its presence has been
noted.
●
● Braun-Blanquet Cover Scale:an abundance scale for measuring percentage cover.
Estimating numbers of mobile animals
Mark-release-recapture technique : as many individuals as possible are caught and each individual is marked
before returning to their own habitat and left to mix randomly with the rest of the population. When enough time
has elapsed for the mixing to take place, another large sample is captured and the number of marked and
unmarked individuals is counted. The proportion of marked to unmarked individuals is then used to calculate an
Definitions
● A species is a group of organisms with similar morphology and physiology, which can breed together to
produce fertile offspring and are reproductively isolated from other species.
● An ecosystem is a relatively self-contained, interacting community of organisms, and the environment in
which they live and with which they interact.
● A habitat describes the place where a species lives within an ecosystem. This term is often used to
mean the kind of place in which a particular species of organisms can live.
● A population is a breeding group and includes all the individuals of that species which can interbreed
with each other
● A community is made up of different species in a habitat.
● Intraspecific competition: competition for limited resources between individuals of the same species.
Opposite is interspecific competition.
● A niche is the role of an organism in an ecosystem.
● Biodiversity is the degree of variation of life forms in an ecosystem.
● Species richness is the number of species in a community.
● Genetic diversity is the diversity of alleles within the genes in the genome of a single species.
● A quadrat is a square frame that marks off an area of ground, or water, where you can identify the
different species present and/or take measurement of their abundance.
● Species frequency is a measure of the chance of a particular species being found within any quadrat.
● Species density is a measure of how many individuals there are per unit area.
● Taxonomy is the study and practice of classification.
● Extremophiles are organisms with optimal growth in environmental conditions considered extreme in that
it is challenging for a carbon-based life form with water as a solvent.
● Habitat fragmentation is when plants and animals either lose their habitats completely or their habitats
become divided into small areas
● A keystone species is a species which has a disproportionately large effect on its natural environment
relative to its abundance.
● Phylogenetic classification is classifying organisms on their basis of descent from a common ancestor.
● Cyanobacteria are a group of photosynthetic bacteria, some of which are nitrogen-fixing, that live in a
wide variety of moist soils and water either freely or in a symbiotic relationship with plants
Ecosystems
● No ecosystems are entirely self-contained as they interact with each other e.g birds migrate from one
ecosystem to another to find food and to breed.
● Ecosystems can be on different scales such as a tropical rainforest which is a complex ecosystem
whereas a sandy desert is very simple.
● An organism’s niche describes where it is, how it obtains energy and how it interacts with both its
physical environment and with other species. How they ‘fit in’ the ecosystem.
● Organisms have adaptations that help them require resources from the environment.
● Communities may remain fairly stable over a period of time or they made be in a process of gradual
change (succession)
● Succession may result in the formation of a stable community which is called a climax community.
● Experiments suggest that if two species have extremely similar niches, then one species will probably
die out when this kind of competition occurs, so that both species will not be able to coexist in the same
community.
Biodiversity
Tropical forests and coral reefs are two of the most species-rich areas on Earth.
Three levels of diversity:
✧ The variation in ecosystems or habitats
✧ The number of different species in the ecosystem and their relative abundance
✧ The genetic variation within each species.
, Endemic species are species that are only found in certain areas and nowhere else.
Species diversity
The more species there are, and the more evenly the number of organisms are distributed among the different
species, the greater the species diversity.
Ecosystems with high species diversity tend to be more stable than ones with limited diversity(more able to
resist changes).
Genetic diversity
All individuals of a species have the same genes, but they do not all have the same alleles of those genes.
The genetic differences between populations of the same species exist because populations may be adapted
slightly differently in different parts of their range. This diversity is important in order to adapt to changes in biotic
and abiotic factors such as resisting new strains of disease.
Assessing species diversity
❖ Collecting organisms and making species lists
❖ Identify and catalogue the types of organism and build a species list.
❖ Identification keys used to name the organisms that they find and the most common of these is a
dichotomous key.
❖ A pooter is a simple piece of apparatus that is used to collect these animals.
❖ Distribution: the spread of different species throughout the ecosystem.
❖ Abundance: the number of individuals of each species.
Sampling
We can take samples from the area we are interested in, and use these to make an estimate of the total
numbers of the area.
Sampling can be random or systematic. If an area looks reasonably uniform with no clear pattern to the way
species are distributed, then it is best to use random sampling.
Random sampling using quadrats.
● Avoids bias.
● Random sampling is important if the results are to be statistically analyzed.
● In practice, it is found that a quadrat with sides of 0.5 m is the best size in many terrestrial situations.
● The usual way to ensure that a sample is random is to mark out an area with measuring tapes and use a
random number generator. Use these random numbers as coordinates to determine the placing of each
quadrat. First you define the area you are going to study and use two sides of this area as axes.
Standing at the origin, you generate two random numbers and use these as coordinates for the 1 m^2
quadrats you are going to place.
● You can use your results to calculate species frequency and species density.
● When plants grow over surfaces forming a covering it is almost impossible to count individuals. Now then
you can use percentage/species cover which tells you the percentage of ground which is occupied by a
particular species. To do this:
● You use a 100cm x 100cm quadrat with wires running across it at 10cm intervals in each direction which
divides it into 100 small squares. You can then decide approximately what percentage is occupied by the
species.
● Percentage frequency tells us how common a species is, but it does not give information on how much
of the species is present once we have recorded it. Percentage cover is an additional measure of
abundance which tells us how much space a species occupies in a sample, once its presence has been
noted.
●
● Braun-Blanquet Cover Scale:an abundance scale for measuring percentage cover.
Estimating numbers of mobile animals
Mark-release-recapture technique : as many individuals as possible are caught and each individual is marked
before returning to their own habitat and left to mix randomly with the rest of the population. When enough time
has elapsed for the mixing to take place, another large sample is captured and the number of marked and
unmarked individuals is counted. The proportion of marked to unmarked individuals is then used to calculate an
