In: Biology
How can you tell when you have adequately species diversity? Explain your answer.
When we say species richness, it mainly refers to number of spcies found in the sample. So the larger the sample, the more we would find species. For species diversity, it is different. Species diversity takes into account both the number of species and the dominance or eveness of species in relation to one other.
FOR EXAMPLE- Let us consider two communities A and B.
COMMUNITY A
SPECIES | NUMBER OF INDIVIDUALS |
---|---|
A | 59 |
B | 12 |
C | 11 |
D | 9 |
E | 6 |
F | 3 |
TOTAL | 100 |
COMMUNITY 2
SPECIES | NUMBER OF INDIVIDUALS |
---|---|
A | 20 |
B | 21 |
C | 13 |
D | 14 |
E | 19 |
F | 13 |
TOTAL | 100 |
The particular measure opf species richness is known as D, the Menhinick's index.
In the above example the total number is individuals are same, and the species remain the same.
When we calculate species richness, we use
D= S / √N
where s equals number of different species represented in the sample, and N equals the total number of individual organism in the sample,we find that the resulting number are sample that is 0.6, because both the samples have the same number of species for the same totak number of individuals. HENCE, for both species richness is identical.
Now, let us consider the species diversity of these two communities. In community A one species, Species A numerically dominates the other five species. In Community B the six species are more evenly distributed. Because of this kindof difference, Community B would considered to be more ''DIVERSE'' than COMMUNITY A despite both communities having the same number of total indiviuduals and the same numbers of species.