Biodiversity Flashcards
(34 cards)
What is the definition of biodiversity?
The variety of living organisms present in an area.
Why is biodiversity so important?
Biodiversity is important in maintaining a balanced ecosystem for organisms as all species are interdependent.
What are the three ways of measuring biodiversity?
- Habitat
- Species
- Genetic
What is meant by habitat biodiversity?
The number of different habitats found within an area - greater habitat biodiversity generally correlates to a greater species biodiversity.
What are the two components to measure species biodiversity?
- species richness - number of different species living in an area
- species evenness - comparison of the number of individuals of each species living in a community
What is meant by genetic biodiversity?
The variety of genes that make up a species - genetic variation (alleles) leads to genetic biodiversity within a species.
What is the benefit of greater genetic biodiversity within a species?
It allows for better adaptations to a changing environment - individuals are more likely to be resistant to disease.
How can random sampling be carried out?
- Marking out a grid using tape measures
- Use random number generation to determine the x and y coordinates within the grid
- Sample at each coordinate pair
What are the 3 types of non random sampling?
- Opportunistic - weakest form as it is not representative of the whole population. Uses conveniently available organisms.
- Stratified - populations are divided into a number of sub groups based on particular characteristics then sampled randomly.
- Systematic - different areas are identified and sampled separately. Often uses a line transect or a belt transect (two lines used and area between is sampled).
Why are sampling techniques not entirely reliable?
- Sampling bias - reduced by random sampling
- Chance - can be minimised by using a larger sample size
How is species richness measured?
Identification keys such as images are used to identify organisms, a list of which is then complied and the total number of species is calculated.
How is species evenness measured?
Individuals are counted and identified.
How are different abiotic factors measured?
- wind speed - anemometer
- light intensity - light meter
- relative humidity - humidity sensor
- pH - pH probe
- temp - temperature probe
- pO2 in water - dissolved oxygen probe
Simpson’s Index of Biodiversity:
D = 1 - { (n/N)^2
{ = sum of total
N = total number of organisms for all species
n = total number of organisms of a particular species
What do Simpsons’ values represent?
Values are always between 0 and 1 - with 0 representing no biodiversity and 1 representing infinite diversity.
Therefore a higher value correlates to a greater amount of biodiversity.
What are the main human factors which impact biodiversity?
- deforestation
- agriculture
- climate change
How is deforestation affecting biodiversity?
- Directly reduces the number of trees present in an area
- Animals are forced to migrate to ensure survival - changing biodiversity patterns
- Reduces diversity of animal species - habitats / food sources destroyed
How is agriculture affecting biodiversity?
- Deforesting land for agricultural use
- Use of chemicals - directly reduces species diversity by destroying pest species, indirectly by destroying food sources of other species.
- Monoculture - lowers biodiversity as only one plant species is growing. Some instances of monoculture destroys habitats.
How can climate change affect biodiversity?
- Melting of polar ice caps could lead to the extinction of animal / plant species - forcing animals to migrate further north.
- Rising sea levels could flood low lying land, reducing the terrestrial habitats. Saltwater flow could also reduce freshwater habitats.
- Higher temperatures / less rainfall would result in extinction of some plant species, and an increasing dominance of xerophytes. Loss of species dependent on said plants.
What are the three reasons to maintain biodiversity?
- aesthetic
- economic
- ecological
What is the primary issue with continuous monoculture?
It causes soil depletion - reduction in the diversity of soil nutrients as the crop removes the same nutrients every year and the nutrients are not recycled.
Soil depletion makes the ecosystem grow fragile, increasing vulnerability to insects / competitors.
What is meant by a keystone species?
Species which have a disproportionately large effect on their environment relative to their abundance - they help determine species richness and evenness.
e.g. sea stars eat mussels and sea urchins which have no other predators. Meaning if sea stars are removed, the other two species’ populations grow uncontrollably.
What is conservation?
The preservation and management of the environment and it’s natural resources to improve organisms’ chances of survival - safeguards species and genetic diversity.
What is meant by in situ and ex situ conservation?
in situ = within the natural habitat
ex situ = out of the natural habitat