17. Biodiversity Flashcards Preview

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Flashcards in 17. Biodiversity Deck (13):

Define biodiversity.

The range and variety of genes, species and habitats within a particular region.


Biodiversity has three components. What are they?

Species diversity: the number of species and the number of individuals in each species within any one community.

Genetic diversity: the variety of genes possessed by the individuals in any one species.

Ecosystem diversity: the range of different habitats within a particular area.


What are the two components of species diversity?

-the number of different species in an area.
-the proportion of the community that is made up of an individual species.


The number of species and the number of individuals in one community are the same. Is the species diversity the same?

No, species diversity depends on the number of individuals in each species in the community, not just the total number of individuals.


Give the formula for the species diversity index.

d= (N(N-1))/(sigma n (n-1))

N= total number of organisms of all species
n= total number of organisms of each species


The higher the species diversity index...

The greater the species diversity.

The more stable the ecosystem is - if the climate changes e.g flooding there is more likely to be at least one species that can tolerate the new habit in a community with a high species diversity than one with a low species diversity.


In hostile conditions.....
In less hostile environments....

The species diversity is usually low, therefore the ecosystem is unstable and the community is dominated by climatic factors rather than the organisms in the community.

The species diversity is usually high, therefore the ecosystem is stable and the community is dominated by living organisms rather than climate.


As natural ecosystems develop over time, they become...

Complex communities, with many individuals of a large number of different species. They have a high species diversity index.


What happens to the species diversity index when farmers use selective breeding in agriculture?

The number of species and the genetic variety of alleles they possess is reduced. The species diversity index is reduced. Any particular area can only support a certain amount of biomass. Species which are not selectively bred must compete for a small amount of space and resources.


Define deforestation.

The permanent clearing of forests and the conversion of the land to other uses.


What is the most serious consequence of deforestation?

The loss of biodiversity.


How many species each year are being lost as a direct result of deforestation?

50000 species


Some areas where there has been deforestation are reforested. Why is there still an overall loss of species diversity?

The new forests grown for commercial purposes have just a few predominant tree types.