Phylogenetic results of 6 morphological character matrices

The construction of morphological character matrices is central to
paleontological systematic study, which extracts paleontological
information from fossils. Although the word information has been
repeatedly mentioned in a wide array of paleontological systematic
studies, its meaning has rarely been clarified and there has not been a
standard to measure paleontological information due to the incompleteness
of fossils, difficulty of recognizing homologous and homoplastic
structures, etc. Here, based on information theory, we show the deep
connections between paleontological systematic study and communication
system engineering. It is information, the decrease of uncertainty, in
morphological characters that distinguishes operational taxonomic units
(OTUs) and reconstructs evolutionary history. We propose that concepts in
communication system engineering such as source coding and channel coding
correspond in paleontological studies to the construction of diagnostic
features and the entire character matrices, which should be distinguished
as how typical communication systems are engineered because these two
steps serve dual purposes. With character matrices from six different
vertebrate groups, we analyzed their information properties including
source entropy, mutual information, and channel capacity. Estimation of
channel capacity shows upper limits of all matrices in transmitting
paleontological information, indicating that, due to the presence of
noise, too many characters not only increase the burden in character
scoring, but also may decrease quality of matrices. Information entropy,
which measure how informative a variable is, of each character is tested
as a weighting criterion in parsimony-based systematic studies, the
results show high consistence with existing knowledge with both good
resolution and interpretability.