What is Biodiversity?
The variety of living organisms within a community
What does a higher biodiversity indicate?
The higher the biodiversity, the more stable the ecosystem
What are the 3 components of biodiversity?
1. species diversity2. genetic diversity3. ecosystem diversity
What is species diversity?
the number of different species and individuals of each species within a community
What is genetic diversity?
The variety of genes within a population of a species
What is ecosystem diversity?
The range of habitats
What are the factors affecting biodiversity?
1. Natural selection2. Succession3. Human Impact
How does natural selection affect biodiversity?
The gradual change of organisms over time can generate and change the biodiversity.
How does succession affect biodiversity?
When a habitat changes over time making it more suitable for other organisms to survive thereeg) sand dunes
How does human impact affect biodiversity?
Humans make environments less inhabitable to organisms which can lead to extinctioneg) deforestation, over fishing, pollution, misuse of land etc
How does natural selection lead to more biodiversity?
1. As environments change, organisms change too2. This can cause more useful features to appear which are selected over and over again.3. Over many generations the population changes leading to more biodiversity.
What events can reduce biodiversity?
1. sudden climate change (dinosaurs)2. insecticides being used
Give examples of adaptive traits...
Anatomical traits:1. Streamlined bodies for swimming2. Nectar guides = help attract pollinatorsPhysiological traits:1. Arctic animals can modify body temp to use less energy in maintaining 37C eg) polar bears drop to 2C during hibernation2. Leaves falling off trees to avoid dehydrationBehavioural traits:1. Mating rituals2. Flowering - only when pollinaters have emerged
What is species richness?
the number of different species in a community
What is the index of diversity?
the relationship between the number of species in a community and the number of individuals in each species
What is Simpson's index of diversity?
The formula used to asses the amount of diversity at population level. - It can be used to monitor any changes or to compare biodiversity in 2 areas.
What is the formula for the Simpsons Index of Diversity?
D = 1- [n (n-1) / N(N-1)
What do N, n and ( mean in the formula?
N = Total number of organisms presentn = number of each species( = The sum of
What is the lowest possible value of D?
1
What does the value of Simpsons Index tell us about species richness?
The higher the number, the higher the species richness
What does low species diversity indicate?
1. Relatively few successful species in the habitat2. The environment is quite stressful with relatively few ecological niches and only a few organisms are really well adapted to that environment.3. Food webs which are relatively simple4. Change in the environment would probably have quite serious effects.
What does high species diversity suggest?
1. A greater number of successful species and a more stable ecosystem.More ecological niches are available and the environment is less likely to be hostile.3. Complex food webs4. Environmental change is less likely to be damaging.
Why is the index of diversity a more useful measure of species diversity than species richness?
1. As well as measuring the number of species, it also measures the number of individuals in a species (different proportions of species)-This takes into account that some species may be present in high/low numbers.