Patterns of Correlation and Covariation of Anthropoid Distal Forelimb Segments Correspond to Hoxd Expression Territories

Document Type

Article

Publication Date

5-15-2008

Abstract

Anthropoids in general and hominoids in particular exhibit differential adaptations in forearm and digital skeletal proportions to a diverse array of locomotor modes. Hox genes act as selector genes with spatially regulated expression patterns during development. Their expression in the forelimb appears to define modules that specify differential skeletal growth. Here we explore forelimb skeletal proportions in a large sample of anthropoids from a background provided by Hoxd expression patterns in late-stage murine embryonic forelimbs. Interspecific correlation and principal components analyses of primate forelimb data indicate that morphological variation in anthropoids reflects well-defined developmental modules downstream of Hoxd expression. The phalanges of digit one appear to represent a single growth module, whereas the metacarpals and manual phalanges of the posterior digits correspond to a second, independent, expression territory that extends proximally into the distal zeugopod. In particular, hominoids show very high correlations among the posterior digits and the independence of digit one. In addition, the distal radius is generally highly correlated with the posterior digits and not digit one. Relying on established functional differences among Hox paralogs, we present a model that parsimoniously explains hominoid forearm and digital proportions as a consequence of downstream effects of Hox. We, therefore, suggest that Hox-defined developmental modules have served as evolutionary modules during manual evolution in anthropoids.

Publication Title

Journal of Experimental Zoology Part B: Molecular and Developmental Evolution

Volume

310

Issue

3

First Page

240

Last Page

258

PubMed ID

18080316

Comments

This article was published in Journal of Experimental Zoology Part B, Molecular and Developmental Evolution, Volume 310, Issue 3, Pages 240-258.

The published version is available at http://dx.doi.org/10.1002/jez.b.21207.

Copyright © 2008.

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