The filtering steps are meant to remove anchor
clusters that are likely to be artefact or are
very unclear.
New filtering criterion: if a cluster is lower
in height than the successive cluster, it is
discarded. The motivation is that any WGD peak
is generally taller than the successive
(older) WGD peak in the distribution, due to
gene loss and Ks stochasticity (increased
variability in substitution accumulation)
among paralogs.
Modified existing filtering criterion: widely
spread clusters (IQR >= 1.1) are now discarded
only if their median Ks is old (>2.6); this
change comes from the fact that some clusters
whose median was actually acceptable (e.g. 2)
were discarded because they were covering a
wide range with a tail up to 5 Ks.
Such species were Poaceae like rice and
sorghum, where there is a wide sigma-tau
signal between 2 and 3.