Download Lesson 1 what is biodiversity

Biodiversity
Objectives
• Define the terms species, habitat, and
biodiversity
• Identify the Levels of biodiversity – habitat,
species, and genetic
• Know how to measure biodiversity by
sampling; taking of random samples
Biodiversity - definitions
Biodiversity
All the different species of organisms
worldwide, the genes they contain and the
ecosystems they are a part of.
Species
Individuals that are very similar in
appearance, anatomy, physiology,
biochemistry and genetics so that they can
interbreed and produce fertile viable
offspring
Ecosystem
All the living (biotic) and non living
(abiotic) components in a specific area
and their interaction
Habitat
a place where an organism or population
lives, including the climate, topography
and abiotic factors there as well as the
plants and animals (biotic factors)
Different aspects of diversity
Habitat Diversity
• the range of habitats in which
different species live
Species Diversity
the number of different species and the
abundance of each species in an
ecosystem.
• Structural - tree and an ant
• Functional – bacteria that cause decay
and those that digest food
Genetic Diversity
• the variation of alleles within a species
(or a population of species).
• Genetic variation between individuals
belonging to the same species
• Note: A number of genes are the same
in different species – similar
fundamental biochemistry and cell
structures – e.g. respiration – requires
same enzymes
The importance of genetic diversity
• allows species to evolve.
• allows organisms to adapt to changes in the
environment such as: climate change,
increased pollution, new disease, new pests
Human effects on biodiversity
• Clearing of natural vegetation reduces
habitat size and Population size of the
species in that habitat
• Hunting
• Introduction of predators and competitors
• Monoculture and selective breeding reduces
variation and genetic diversity and could
lead to extinction of some varieties within a
species (genetic erosion) reducing overall
gene pool for the species. Decreased genetic
variation reduces the ability of the species
to adapt and evolve
Measuring biodiversity
• Need to find out what species are
present in a habitat and what population
size there is
• Sampling can be random or systematic
• Most plant sampling techniques use
quadrats
Quadrats
Use square framed quadrats to measure
plant abundancy
Place the quadrat, identify the species and
then assess their abundancy or percentage
cover
Point quadrats
Have 10 metal pins in a row. Place in quadrat
and count the number of plants each pin
touches
Random sampling
• Random uses chance to determine the sampling
points and eliminates bias
• Mark the area to be sampled as a grid
• use random numbers to generate coordinates to
place quadrat
• Identify and count plants
Systematic sampling
• To measure how vegetation changes e.g. from
the shore away from the sea
• Use systematic sampling with a transect
• Place a quadrat at regular intervals along the
transect
• Identify and count the plants
Line Transect
A line (rope or tape) is laid across a habitat
Record all the plants of the sampled species
touching the line at set intervals along it
Belt Transect
Place a series of frame (or point) quadrats along a
line at regular intervals (interrupted belt) or move
them along the length (continuous belt)
Count and identify the organisms in each quadrat
A belt transect gives both distribution and
abundance.
Sampling Plants
• Large plants can be counted
• Smaller plants usually assessed by
percentage cover
• ACFOR is used as an abundancy scale
A
Abundant
C
Common
F
Frequent
O
Obvious
R
Rare
ACFOR
Sampling Animals
Sampling animals offers the challenge of
counting mobile organisms
Sampling of large animals can be
considered unethical so tracing tracks,
droppings and food is used.
Sampling of invertebrates has more variety
of methods and not considered to be
unethical.
Light trapping
(really good for moths)
Trap, identify and count
Tullgren funnel
Sweep netting
Consider size of net, sweeping action, no of
sweeps, suitability to organisms and habitat
Pooter
To make a fair comparison
between habitats
• Sample randomly
• use the same sampling technique and
same procedure – e.g. number of
quadrats, number of sweeps with net,
method of sweep, number of sweeps
Current Estimates of Global Biodiversity
• Between 1.5 and 1.75 million species have been
estimated to be present globally by scientists.
• The figures are not exact
• there is no central database of all species
• different opinions exist between scientists
about the classification of certain species
• A large proportion of species on earth have
not been named
• Many species are undiscovered or known but
not yet named
Current
estimates of
global
biodiversity are
too low
Different techniques being used to make estimates
Lack of information for some species – e.g. bacteria
and insects
Variations in biodiversity in different parts of the
world due to geographical factors. The greatest
diversity is near the equator and it decreases
towards the poles.
Large areas of tropical rainforests, the poles, and
deserts not yet explored
Climate change affecting biodiversity
Continuing evolution and speciation
Many species becoming endangered or are becoming
extinct
Estimates change as scientists find out new
information
Do not take into account numbers of individual
species or variation between or within species
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