3.5 Indicators
Indicator classifications are shown in Figure 7. In summary, theΔH indicator detects reduction of genetic diversity within
several populations (Figure 7a), but metapopulation systems buffer
against some of these trends so that when metapopulations are considered
– increase and decrease within separate subpopulations levels out
(Figure 7b). This is not the case in all systems however, and theN e-indicator provides warning signals of low
effective population sizes in 6 out of 10 systems studied (Figure 7b).
The ΔF ST indicator shows that gene flow is
significantly decreasing in the same metapopulation (Skåarnja 2) were we
also observe ΔH and N e warning signals.
However, the change of F ST reflects an expected
reduction genetic exchange that is less than the proposed threshold
value, i.e., the number of migrants between subpopulation is estimated
to have been reduced by less than 25% over the monitoring period
(Figure 7b).