Shannon and Simposon index

[Mantella86 (Martyn)]

Hi all, what could be the reason that observed diversity is high in a certain treatment but the Shannon and Simpson diversity is low and vica versa?

Best wishes

[colinbrislawn (Colin J Brislawn)]

I've got some examples of how diversity metrics work over here:

Chao1 and Shannon negatively correlated

Hello everybody, I am reporting Chao1 (species richness) and Shannon (eveness) to characterize alpha diversity in different microbiomes. Both indexes are negatively correlated in my data: as Chao1 increases, Shannon decreases. Is that possible? I am having a hard time to find a biological interpretation. Any suggestion? Thanks in advance! Pablo

The short answer is that 'Observed' is a richness only metric, while Shannon and Simpson measure both richness and evenness, so changes in evenness will also be shown.