Evolution of Ecomorphological Diversity

Jonathan B. Losos

in Lizards in an Evolutionary Tree

Published by University of California Press

Published in print August 2009 | ISBN: 9780520255913
Published online March 2012 | e-ISBN: 9780520943735 | DOI:
Evolution of Ecomorphological Diversity

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This chapter presents the phylogenetic analysis of evolutionary diversification within anole ecomorphs, addressing whether the phylogenetic relationships among the ecomorph classes are the same across islands. It also draws conclusions from anole phylogeny about the age of the ecomorph phenomenon, and suggests that evolutionary and ecological processes have been at work in shaping size distributions. Two hypotheses for size evolution are described. One possibility is that the size differences evolved by character displacement, a phenomenon whereby when two similar species come into contact, they evolve in opposite directions to minimize resource overlap, thus permitting coexistence. The second possibility is the taxon cycle or taxon loop hypotheses. The idea of these hypotheses is that intermediate size is optimal, but that sympatry of large and small species is not produced by divergence in opposite directions, but by a large species invading an island occupied by an intermediate-sized species, which then evolves to smaller size.

Keywords: evolutionary diversification; ecomorphs; size evolution; character displacement; taxon cycle; taxon loop

Chapter.  7484 words.  Illustrated.

Subjects: Evolutionary Biology

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