2.2. BIODIVERSITY STUDIES
Species assemblages in a particular habitat especially at different elevational gradients can be useful in evaluating the community response to transforming macro and micro environment due to climate change as recorded in the findings of various workers (Rahbek 1995, 2005; McCain & Grytnes 2010; Fischer et al ., 2011; Lefebvre et al ., 2018; Chatelain et al ., 2020). The count on leafhoppers’ morphospecies was used to calculate species diversity, diversity distribution patterns using the following indices:
2.2.1. Simpson-Yule Index (D): Simpson diversity index measures the probability that two individuals randomly selected from a sample will belong to the same species. For calculating Simpson Index number of individuals of different species of leafhoppers and a total number of individuals in all the species of leafhoppers were counted and arranged for estimation of Simpson’s diversity index. Simpson (1949) index is expressed as:
Sobs
D=1/C D = ∑Pi2
i-1
Ni (Ni - 1)
Where, Pi2 =
NT (NT - 1)
But approximated as, Pi2 = (Ni/ NT) 2
Ni is the number of individuals in the ith species and NT the total individuals in the sample
Simpson Inverse= 1/D
2.2.2. Shannon-Wiener Index (H): is the measurement of the diversity of species in a community or habitat. For calculating Shannon- Wiener index observations on the total number of leafhoppers in a particular species and a total number of individuals of all species of leafhoppers in the whole sample was used for diversity analysis through Wiener index. Thus it is an index applied to biological systems derived by (Shannon 1948) and combined both species richness and evenness. The diversity index was calculated as per the formula is given below:
Shannon Diversity Index (H’) = -∑Pi loge Pi
Where;
Pi= S/N (P- the proportional abundance of ith species)
S= Number of individual of one species
N= Total number of all individual in the sample
loge= logarithm to base e
2.2.3. Measurement of evenness: Species evenness refers to, “how close in numbers each species in an environment is”. For studying species evenness; the total number of species collected were counted and used in measuring the evenness along with Shannon’s diversity index. The species evenness was calculated as per the following formula.
Species evenness (J) = H/ ln S
Where;
H= Shannon-Weiner index
S= Total number of species in the sample
ln= natural logarithm
2.2.4. Measurement of dominance : It is the simple measure of the numerical importance of the most abundant species. Decreasing dominance values indicates diversity. For studying species dominance; the total number of species collected were counted and used in measuring the dominance from Shannon- Winer diversity index. It is calculated as per formula.
Species dominance = 1-J
Where; J= Evenness
2.2.5. Measurement of species richness : This indicates the total number of species in each sample. Species richness is the number of different species represented in an ecological community, landscape or region. To know the species richness, the total number of individuals of different species collected in the sweep net and light traps were counted and also the numbers of different species represented by these individuals were counted. The Margalef diversity index (Margalef, 1958) can be calculated in a spreadsheet by the equation:
Margalef’s Index of species richness = (S-1)/ ln N
Where;
d= Margalef’s Index of species richness
S= Total number of species
N= Total number of individual in the sample
ln= natural logarithm
Calculations of the Shannon-Wiener Diversity Index (H’), Simpson’s diversity index (D), Evenness, abundance, and species richness were done using Microsoft Excel.