An introduction to biodiversity Flashcards
What is species diversity?
A product of 2 variables
> the no. of species (richness) +
> their relevant proportions (evenness)
What is genetic diversity?
The range of genetic material present in a gene pool or population of a species
In order to conserve the maximum amount of genetic diversity, what needs to be conserved?
If a species is made up of 2 or more different populations in different places, then each population will have a different total genetic make-up.
Therefore to conserve the maximum amount of genetic diversity, different populations of a species need to be conserved
Example of organism with small genetic diversity
Grey seals
Almost all of which live on the Farne islands off the north-east coast of England
Example of organism with large genetic diversity
European red fox
Found right across Europe
How can humans alter genetic diversity?
By artificially breeding // genetically engineering populations with reduced variation in their genotypes or even identical genotypes (clones)
This is an advantage if produces a high-yielding crop or animal
Disadvantage if disease strikes + whole population is susceptible
This domestication + plant breeding has lead to loss in genetic variety, hence the importance of ‘gene banks’
What is habitat diversity?
The range of different habitats per unit area in a particular ecosystem or biome
Name a biome with high habitat and one with low habitat diversity
Tropical rainforests are high in habitat diversity as there are many ecological niches due to the layering of the forests
Tundra has a low level of habitat diversity
3 advantages of a habitat with high biodiversity
> resilience + stability due to range of plants present, so some will survive drought, floods, disease etc..
> genetic diversity so resistance to disease
> some plants will have deep roots so can cycle nutrients + bring them to surface so make them available for other plants
3 ways high biodiversity doesn’t equate to a healthy ecosystem
> diversity may be result of fragmentation of a habitat or degradation when species richness is due to pioneer species invading bare areas quickly
> managing grazing difficult as plant species have different requirements + tolerance to grazing
> some stable + healthy communities have few plant species so are exceptions to rule
Why is it important to repeat investigations of diversity in the same community over a period of time?
- To know if change is a natural process due to succession or due to impact from human activity
- This could either increase // decrease biodiversity, telling us if conservation efforts are succeeding or not
What is a biodiversity hotspot?
A region with a high level of biodiversity that is under threat from human activities
- May have more species + more of each species than other areas
- May have unusually high numbers of endemic species
About 30 biodiversity hotspots have been recognised. Why have they been recognised and where are they?
> 10 in tropical rainforest
more near tropics (fewer limiting factors)
all threatened areas (70% habitat already lost)
habitat has 1,500+ species endemic plant
cover only 2.3% of land surface
tend to have large densities of human habitation nearby
What proportion of the world’s species do biological hotspots contain?
Between them they contain 60% of the world’s species so have v high species diversity
Critics of naming hotspots say they can be misleading because they:
- focus on plants + ignore animals
- do not represent total species diversity
- focus on regions where habitats have been lost + ignore whether loss is still happening
- do not consider genetic diversity
- do not consider value of services e.g. water resources
