Biodiversity (UNIT 2) Flashcards
BIODIVERSITY
The general term used to describe variety in the living world.
Refers to the number and variety of living organisms in a particular area.
SPECIES DIVERSITY
Refers to number of species and the number of individuals of each species within any one community.
GENETIC DIVERSITY
Refers to the variety of genes possessed by the individuals that make up any one species.
ECOSYSTEM DIVERSITY
Refers to the range of different habitats within a particular area.
What are the two components of species diversity?
- The number of different species in a given area.
- The proportion of the community that is made up of an individual species.
How can two communities be different if they have the same number of species?
The proportions of the community made up of each species may differ.
How can you calculate species diversity?
Use an index- calculated as follows:
d=N(N-1)/Σn(n-1)
d=species diversity index
N=total number of organisms of all species.
n=total number of organisms of each species.
Σ= the sum of
THE HIGHER THE VALUE OF d THE GREATER THE SPECIES DIVERSITY.
What does a higher species diversity mean to an ecosystem?
The higher the species diversity, the more stable the ecosystem tends to be and the less it is affected by climate change.
What is the species diversity usually like in places with extreme conditions? Why?
usually low because only a few species have the necessary adaptations to survive the harsh conditions.
Less stable ecosystem.
What is the impact of agriculture on species diversity?
Farmers select species for particular qualities that make them more productive.
AS A RESULT
Number of species and the genetic variety of the alleles they possess, is reduced to the few that exhibit the desired features.
To be economic number of these desired species needs to be LARGE.
Any particular area can only support a certain amount of biomass.
If most of area taken up by one desirable species, smaller area for other species.
Other species have to compete for what little space and resources are available.
Many will not survive competition.
Also pesticides are used to eliminate these species because they compete for light, mineral ions, water and food required by the farmed species.
OVERALL EFFECT IS REDUCED SPECIES DIVERSITY.
SPECIES DIVERSITY INDEX LOW.
BIOMASS
The total mass of living material, normally measured in a specific area over a given period of time.
What is the impact of deforestation of species diversity?
Forests cover many layers between the ground an the tops of trees, so there are many habitats available.
HIGH SPECIES DIVERSITY. (highest of any ecosystem)
Some deforestation result of accidental fires, the vast majority is due to deliberate human actions.
Deforestation causes loss of biodiversity.
Tropical rainforests account for half of the earth’s species despite only covering 7%.
Replacement of forests by agriculture, housing or reservoirs has considerably reduced species diversity.
DEFORESTATION
The permanent clearing of forests and the conversion of land to other uses, such as agriculture, grazing, housing and reservoirs.
How come, even where areas are reforested, there is still an overall loss of species diversity?
The new forests are grown for commercial purposes have just a few predominant tree types.
