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Comparative Meristic Variability in Whiptail Lizards (Teiidae,
Aspidoscelis): Samples of Parthenogenetic A. tesselata Versus
Samples of Sexually Reproducing A. sexlineata, A. marmorata, and
A. gularis septemvittata
Author(s): Harry L. Taylor, Charles J. Cole, Glenn J. Manning, James E. Cordes, and
James M. Walker
Source: American Museum Novitates, (3744):1-24. 2012.
Published By: American Museum of Natural History
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Copyright © American Museum of Natural History 2012 ISSN 0003-0082
A M E RI C A N M USE U M N OV ITATES
Number 3744, 24 pp. May 23, 2012
Comparative Meristic Variability in Whiptail Lizards (Teiidae, Aspidoscelis): Samples of Parthenogenetic A. tesselata Versus Samples of Sexually Reproducing A. sexlineata, A. marmorata, and A. gularis septemvittata
HARRY L. TAYLOR,1 CHARLES J. COLE,2 GLENN J. MANNING,3
JAMES E. CORDES,4 AND JAMES M. WALKER5
Is it correct, as is often assumed, that the clonal form of inheritance in parthenogenetic lizards results in less variability than occurs with genetic recombination in their sexually reproducing (gonochoristic) relatives? We tested this hypothesis by comparing morphological variability in samples of parthenogenetic Aspidoscelis tesselata and several gonochoristic species of whiptail lizards. To control for environmental factors that might differentially affect embryonic development of morphological characters, we compared samples obtained from the same or geographically adjacent localities. In addition, we compared apparently “uniclonal” and multiclonal samples from each of two color-pattern classes (C and E) of A. tesselata.
For univariate meristic characters, parthenogenetic A. tesselata matched the variability of a sympatric gonochoristic species in 11 of 20 comparisons, had lower variability in six comparisons, and was more variable in three. For multivariate characters derived from principal components analyses (PCA), the relative meristic variability of samples of A. tesselata could not 1Division of Vertebrate Zoology (Herpetology), American Museum of Natural History; Department of Biology, Regis University, Denver, CO 80221. 2Division of Vertebrate Zoology (Herpetology), American Museum of Natural History. 3School of Mathematical and Natural Sciences, University of Arkansas–Monticello, Monticello, AR 71656. 4Division of Sciences and Mathematics, Louisiana State University Eunice, Eunice, LA 70535. 5Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701. 2 AMERICAN MUSEUM NOVITATES NO. 3744 be predicted by its reproductive mode, color-pattern class, apparent “uniclonal” or multiclonal state, or geographic location.
In addition, we compared A. tesselata, A. sexlineata, A. marmorata, and A. gularis septemvittata in a single PCA, with the latter two species representing the two ancestral taxa from which
A. tesselata was derived through hybridization. Once again, relative variability of A. tesselata was not always predictable based on its reproductive mode. It had greater variability than A. sexlineata, equivalent variability with A. gularis septemvittata, and less variability than A. marmorata.
It is with great pleasure that we dedicate this work to two North American herpetologists who were pioneers in recognizing that some species of whiptail lizards are unisexual, which challenged everything they had learned about reproduction of tetrapods. These two scientists were also among the first to provide comparative analyses of variation involving Aspidoscelis tesselata, wondering whether it would have less variation than gonochoristic species. One was T. Paul Maslin (deceased),
University of Colorado, in whose memory we make this dedication, and the other is Richard G.
Zweifel, American Museum of Natural History, who is retired and living in Portal, Arizona.
Zweifel, on October 10, 1958, wrote to colleagues and announced that I.S. Darevsky (1958) had reported probable parthenogenesis in some Armenian lacertid lizards, indicating that this might explain samples of whiptail lizards from North America that lacked males (Lowe, 1993).
Later, in Duellman and Zweifel (1962), Zweifel reported that several species of Aspidoscelis are all-female species, and they might be parthenogenetic; however, at that time, Duellman did not believe the material on all-female populations that Zweifel put in their paper (personal communication from Duellman to C.J.C.). In addition, Zweifel (1965) analyzed comparative morphological variation in lizards, including A. tesselata, to see if samples were less variable than samples of gonochoristic species. We know that study had been underway since the late 1950s, because
Zweifel took C.J.C. as an undergraduate student assistant to one of his New Mexico study sites in 1960 while discussing emerging thoughts about parthenogenesis in whiptail lizards.
Maslin (1962) first reported that some species of Aspidoscelis, including A. tesselata, are all-female species. He then used skin grafting experiments to test whether individuals might be genetically identical (Maslin, 1967), and contributed a seminal position paper on taxonomic problems in parthenogenetic vertebrates, in which he also discussed relative variability and reproductive mode (Maslin, 1968).