topic 4

Biodiversity is the variety of living organisms in an area. It includes:

species diversity-The number of different species and abundance of each species in an area 

genetic diversity-The variation of alleles within a species

Endemism is when a species is unique to a single place-e.g the giant tortoises is endemic to galapagos islands

NATURAL SELECTION leading to adaptation and evolution can increase biodiversity but human activities e.g farming and deforistation can reduce biodiversity.

conservation is needed to help maintain biodiversity.it is really important for endemic species as they are vulnerable to extinction.

Species diversity can be measured, and compared to different habitats.

you can measure this in 2 ways:

1)

• count the number of different species in an area 
• the number of different species in the area is called species richness,the higher the number of species the greater the species richness---however species richness gives no indication of the abundance of each species.

2)

• count the number of different species and number of individuals in each species.
• then use an index of diversity-to calculate species diversity

This is easily done 

Choose an area to sample, to avoid bias do it randomly.

For plants use a quadrant, insects use a sweep net,

for ground insects use a pitfall trap,

and aquatic animals use a net.

Then repeat the process and take as many samples as possible to give a better indication of whole population 

Diversity if the variety shown by indiviaduals of the population 

individuals of the same species vary because they have different alleles 

genetic diversity is the variety of alleles in the gene pool of a species

The gene pool is the complete set of alleles in a species.

The greater the variety of alleles the greater the genetic diversity

Genotype-The gentic makeup of the organim

The genotype of an organism demonstrates the alleles present for a particular characteristic.

phenotype 

The observable charecteristics of an organims.

By looking at the phenotypes you get an idea of the diversity of alleles in the population.

you can measure genetic diversity within a species using the heterozygosity index

heterozygotes have 2 different alleles at a particular locus--A higher proportion of herozygotes means the population has a greater genetic diversity.

H =  number of herozygotes/number of individuals in population