Interspecific morphologic variation in kangaroo rats (dipodomys): Degree of concordance with genic variation

Abstract

Schnell, G. D. (Department of Zoology and Stovall Museum, University of Oklahoma, Norman, Oklahoma 73019), T. L. Best (Natural Sciences Research Institute, Natural History Museum, Eastern New Mexico University, Portales, New Mexico 88130), and M. L. Kennedy (Department of Biology, Memphis State University, Memphis, Tennessee 38152) 1978. Interspecific morphologic variation in kangaroo rats (Dipodomys): Degree of concordance with genic variation. Syst. Zool. 27:34-48.-The 24 forms of kangaroo rats (Dipodomys) that have been recognized as species by one or more recent authors were studied using phenetic techniques. A total of 41 morphometric characters (4 skin, 16 skull, and 21 post-cranial) were measured for up to 10 males and 10 females of each species. The standardized average measurements were analyzed and then measurements were divided by principal component I projections based on unstandardized data to reduce the influence of overall size. Phenograms and three-dimensional principal component models were produced and the results compared with the findings of previous authors, including those from allozyme analyses. Several species pairs and groups involving a few species were stable throughout our studies and consistent with groups identified in phylogenetic, specialization, or other classificatory schemes. These include: Compactus and ordii-, elephantinus and venustus; agilis, paralius, peninsularis, and antiquarius; nitratoides and merriami; and ornatus and phillipsii. However, marked morphologic gaps (other than those based on size) are not present between many of the species groups and attempts to place species into such groups in classifications probably result in an indication of distinctness that goes beyond what is found in nature. In terms of interspecific comparisons, there was no association between phenetic groups based on morphologic data and those constructed using allozyme findings. When comparisons were made among previous classifications and our results, the allozyme data produced the most divergent classifications. Overall, the associations between our morphologic results and previous classifications were relatively weak, reflecting by and large the variance in arrangements of species groups, rather than major differences within groups. Given the relative indistinctness of morphologic groups, it seems unlikely that any one classification can accurately represent interspecific phenetic, cladistic, and/or phylogenetic affinities within the genus. [Phenetics, taxonomic congruence, Dipodomys, kangaroo rats, morphometries, allozymes.]. © 1978 Oxford University Press.

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Systematic Zoology

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