I have collected 70 organisms from 4 different sites; two sites of treatment 1 and two sites of treatment 2. I also have a continuous explanatory variable (average temperature) which is different for each site. How can I test if measures of richness and diversity differ between sites or by temperature?
Richness is the number of species in each sample
Diversity is a weighted average of the proportions of each species present. In this case we are using the Shannon Index which is:
$^1\!D= \exp\left(-\sum_{i=1}^R p_i \ln p_i\right)$
where $p_i$ is the proportion of each species $i$ at that site, and $R$ is the richness of the site.
What sort of model can I use when diversity and richness are my response variables?
This question had been abandonned by the OP without giving enough info to answer it properly, the above is an attempt to provide an answerable question in the spirit of what was asked.
Original Question:
I have collected ca. 70 species of organism from 4 sites. 2 sites of Treatment 1 and 2 sites of Treatment 2. How do I test using R, whether the richness, dominance, abundance and diversity is different between the two if I have 6 explanatory variables?