Phylogenetic miniaturization has a name: the Lilliput effect

Just learned this yesterday
and glad to see someone else recognizes and has given a name to phylogenetic miniaturization. Size matters!!! …according to the large reptile tree and large pterosaur tree. New animal taxa tend to originally develop at a small size, as hypothesized by S.M. Stanley (1973).

According to Wikipedia
The Lilliput effect (Urbanek 1993) is a term used to describe a decrease in body size in animals which have survived a major extinction. There are several hypotheses as to why these patterns appear in the fossil record, some of which are: the survival of small taxa, dwarfing of larger lineages, and the evolutionary miniaturization from larger ancestral stocks”

Berv and Field 2017
find an Avian Liilliput Effect at the K-Pg boundary.

From the abstract:
“Survivorship following major mass extinctions may be associated with a decrease in body size—a phenomenon called the Lilliput effect. Body size is a strong predictor of many life history traits (LHTs), and is known to influence demography and intrinsic biological processes. Pronounced changes in organismal size throughout earth history are therefore likely to be associated with concomitant genome-wide changes in evolutionary rates. Here, we report pronounced heterogeneity in rates of molecular evolution (varying up to ∼20-fold) across a large-scale avian phylogenomic data set and show that nucleotide substitution rates are strongly correlated with body size and metabolic rate. We also identify potential body size reductions associated with the Cretaceous–Paleogene (K-Pg) transition, consistent with a Lilliput effect in the wake of that mass extinction event. We posit that selection for reduced body size across the K-Pg extinction horizon may have resulted in transient increases in substitution rate along the deepest branches of the extant avian tree of life. This “hidden” rate acceleration may result in both strict and relaxed molecular clocks over-estimating the age of the avian crown group through the relationship between life history and demographic parameters that scale with molecular substitution rate. If reductions in body size (and/or selection for related demographic parameters like short generation times) are a common property of lineages surviving mass extinctions, this phenomenon may help resolve persistent divergence time debates across the tree of life. Furthermore, our results suggest that selection for certain LHTs may be associated with deterministic molecular evolutionary outcomes.”

Still unrecognized by other pterosaur workers
the large pterosaur tree and large reptile tree recover a Lilliput effect at the base of every major pterosaur clade and elsewhere (turtles, reptiles, lizards, mammals, placentals, bats, etc. ) While other workers find the Lilliput effect in the aftermath of mass extinctions, the LRT found smaller taxa prior to mass extinctions survived the events, while others, like Late Cretaceous large pterosaurs, did not.

Berv JS and Field DJ 2017. Genomic Signature of an Avian Lilliput Effect across the K-Pg Extinction. Systematic Biology syx064
Harries PJ and Knorr PO 2009. What does the ‘Lilliput Effect’ mean? Palaeogeography, Palaeoclimatology, Palaeoecology 284:4–10. online
Stanley SM 1973. An explanation for Cope’s Rule”. Evolution. 27: 1–26. doi:10.2307/2407115
Urbanek A 1993.
Biotic crises in the history of Upper Silurian graptoloids: APalaeobiological model. Historical Biology, 7:29-50.


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