F212 3 Biodiversity Flashcards
What Influences Biodiversity
1) Species Richness - the number of species found in a habitat
2) Species Evenness - the relative numbers or abundance of individuals in each species
Biodiversity
The variety of living things
Genetic diversity - variation within a species
Species diversity - the number of different species an the abundance of each species
Habitat Diversity - the range of habitats in which different species live
Simpsons Index of Diversity
Equation
D = 1 - (the sum of (n/N)^2)
n = number of individuals of a particular species
OR percentage cover for plants
N = the total number of individuals of all species or the percentage cover for plants
Simpsons Index of Diversity
High Value
A more biodiverse area with greater species richness and species evenness
A stable environment
Able to survive environmental changes
Species
A group of organisms that can interbreed to produce fertile offspring
Habitat
The place where an organism or population lives
Simpsons Index of Biodiversity
Low Value
A less biodiverse area with lower species evenness and species richness
An unstable environment
Less resistant to any kind of change
Types of Biodiversity
Species diversity - the differences between species, may be obvious or functional
Habitat diversity - the range of different habitats in which different species live
Genetic Diversity - variation between individuals of the same species which ensures that we don’t all look alike
Random Sampling
Instructions
Take samples at regular distances across the habitat
Use random numbers to generate coordinates within the habitat
Select coordinates from a map of the area and use a portable GPS to find the exact position
Random Sampling
Purpose
Removes bias
Current Global Estimates of Biodiversity
Estimate
In 2001 the Catalogue of Life was created to become a comprehensive guide of all known species
The estimated number of known species is 1 800 000
Some scientists believe that this is only 10% of the total number of species on the planet
Current Estimates of Global Biodiversity
Accuracy
We cannot be sure if we have found all the species on earth
New species are constantly discovered
Evolution and speciation are continuing
Many species are endangered and some become extinct
Random Sampling
Definition
Studying small parts of a habitat and assuming it contains a representative set of species that an be applied to the entire habitat
Species Richness
Definition
The number of different species in an area
Species Evenness
Definition
The number of each species in an area
Species Richness
Estimating
Use a qualitative survey
Record what different species you see
Species Evenness
Estimating - Plants
Carry out a quantitative survey
Use a random sampling technique to select the sample areas
Count the number of plants of each species in the sample
OR
Measure the percentage cover of each species
Importance of Sampling
Cheaper and faster than surveying an entire area
Gives representative data
Allows data to be gathered across larger areas
Species Evenness
Estimating - Animals
For larger animals - carefully observe and count the number of individuals present
For smaller animals - capture a sample of animals and mark them C1
Release the and leave the traps for a set time
Mark the animals caught C2
Release and leave the traps for a set time
Mark the animals caught C3
Total Population = (C1 x C2) / C3
For tiny animals in soil or water - take a sample of soil/water and sift through it counting the number of individuals you find
Use this to estimate the population size and density
