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QUANTIFYING PASSIVE AND DRIVEN LARGE‐SCALE EVOLUTIONARY TRENDS
Author(s) -
Wang Steve C.
Publication year - 2001
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.0014-3820.2001.tb00602.x
Subject(s) - skewness , clade , biology , evolutionary biology , partition (number theory) , scale (ratio) , phylogenetics , statistics , mathematics , cartography , genetics , geography , combinatorics , gene
.— I introduce a new statistical method, analysis of skewness, for quantifying large‐scale evolutionary trends as a combination of both passive and driven trends. My approach is based on the skewness of subclades within a parent clade. I partition the total skewness of the parent clade into three components: (1) skewness between subclades; (2) skewness within subclades; and (3) skewness due to changes in variance among subclades. The third component corresponds to a new type of passive trend, in which overall skewness of a parent clade is due to greater variability in subclades to the right of the mean. Using this partitioning, I decompose an observed trend into two components: a driven portion and a passive portion, thus quantifying the effect of small‐scale dynamics on large‐scale behavior of clades. Applications are given to Miocene‐Pliocene rodent size and Ordovician brachiopod muscle geometry.