Most of the organisms (Living things/Biotic) need nonliving (abiotic) things to live in, such as caves, tunnels, under rocks (for the smaller ones.), water, etc.
I believe it would be the 2-3 Hg thing on there.
as far as i know the mouse is the secondary consumer.
Answer: Gene flow is the movement of alleles from one population to another as a result of the migration of individuals. This causes a reduction in the differences between populations. ... Genetic drift is a change in allele frequencies due to change of events in a small breeding population.