Document Detail

Morphological evolution of subterranean mammals: integrating structural, functional, and ecological perspectives.
MedLine Citation:
PMID:  2408074     Owner:  NLM     Status:  MEDLINE    
The widely recognized convergence of subterranean mammals offers unique opportunities for the study of patterns, causes and consequences of morphological integration. For example, behavioral and biomechanical observations have revealed a diversity of digging modes among subterranean mammals. In rodents, scratch-digging and chisel-tooth digging, alone or combined, are widespread. This dual nature of the digging apparatus must be understood to avoid erroneous assessments of specializations based on forelimb modifications only. Additionally, bulldozing and disposal of loose soil is performed by head-lifting, by means of the forelimbs, or with the hindlimbs. Insectivores are known to resort to scratch-digging, sand-swimming, or to a unique system known as humeral rotation. Semi-fossorial species among rodents and insectivores are scratch-diggers. In contrast, fully subterranean taxa show further specializations for scratch-digging and/or resort to some of the other digging modes. The ecological correlates of these morphological trends are still poorly known; work in geomyids suggests that scratch-digging specializations are efficient in friable soils, whereas tooth-digging allows the utilization of a much broader spectrum of soil types. This indicates that alternative pathways of morphological specialization are not equivalent in their ecological potentialities. Important morphological features, such as incisor procumbency among tooth-diggers, are shown to be constrained by structural, allometric, and mechanical factors. In geomyids, the same procumbent morphologies may be acquired as a byproduct of size increases, by means of adaptive shifts independent from size, or by a combination of both. Thus, geometric similarity may not be indicative of functional similarity. Further constraints result from the integration of different functions. For instance, it is suggested that mastication imposes limitations upon potential modifications of jaw morphology for tooth-digging. Scratch-digging appears to be less constrained by locomotion, but the effects of integration of various functions in fore- and hind-limbs are largely unexplored. Multiple approaches, combining behavioral, functional, ecological, structural, and phylogenetic data, are necessary for the study of morphological evolution among subterranean mammals.
E P Lessa
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Progress in clinical and biological research     Volume:  335     ISSN:  0361-7742     ISO Abbreviation:  Prog. Clin. Biol. Res.     Publication Date:  1990  
Date Detail:
Created Date:  1990-04-03     Completed Date:  1990-04-03     Revised Date:  2005-11-16    
Medline Journal Info:
Nlm Unique ID:  7605701     Medline TA:  Prog Clin Biol Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  211-30     Citation Subset:  IM    
Museum of Vertebrate Zoology, University of California, Berkeley 94720.
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MeSH Terms
Behavior, Animal / physiology
Moles / physiology
Rodentia / physiology*

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