Browsing by Author "Manning, Glenn J."
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Item 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. (American Museum novitates, no. 3744)(American Museum of Natural History., 2012-05-23) Taylor, Harry Leonard.; Cole, Charles J.; Manning, Glenn J.; Cordes, James E.; Walker, James M. (James Martin)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 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.Item Hybridization between parthenogenetic lizards (Aspidoscelis neomexicana) and gonochoristic lizards (Aspidoscelis sexlineata viridis) in New Mexico : ecological, morphological, cytological, and molecular context. American Museum novitates ; no. 3492(New York, NY : American Museum of Natural History, 2005) Manning, Glenn J.; Cole, Charles J.; Dessauer, Herbert C.; Walker, James M. (James Martin)Whiptail lizard guilds consisting of different combinations of parthenogenetic Aspidoscelis exsanguis, Aspidoscelis neomexicana, and Aspidoscelis tesselata pattern classes C and D and gonochoristic Aspidoscelis sexlineata viridis inhabit numerous sites in the immediate vicinity of Conchas Lake, San Miguel County, New Mexico. Based on morphological identification by other workers of specimens collected in 1978, A. neomexicana was the species most recently added to the list of whiptail lizards known to occur at Conchas Lake, about 190 km east of its main distribution area in the Rio Grande Valley. We sampled guilds consisting of A. neomexicana and its congeners at Conchas Lake from 2000 through 2003. In 2002 we also collected specimens of what appeared to be another tokogenetic array of A. neomexicana east of the Rio Grande Valley in syntopy with A. tesselata E and A. sexlineata viridis at Fort Sumner, De Baca County, New Mexico. Comparison of karyotypes revealed that individuals of A. tesselata and those assigned by their discoverers to A. neomexicana from Conchas Lake and Fort Sumner have identical diploid karyotypes (2n = 46) that include diagnostic haploid complements of chromosomes derived from independent hybridizations between species in the tigris and sexlineata species groups. Consequently, we used electrophoretic data for 23 gene loci, of which the sMDH, sMDHP, sIDH, ESTD, PEPA, PEPB, ADA, MPI, GPI, and PGM2 loci were definitive, to further validate the hypothesis that the disjunct groups of putative A. neomexicana in eastern New Mexico had been correctly identified. The specimens analyzed electrophoretically also indicated that the Conchas Lake clone of A. neomexicana is identical to the most widely distributed clone of the species in the Rio Grande Valley of New Mexico and that the Fort Sumner clone possessed a distinctive allele. We describe the habitat for A. neomexicana at Conchas Lake at three sites north of the Canadian River and two sites south of the river. Two of the sites north of the Canadian River were studied as examples of guilds that did not include A. sexlineata viridis. The latter species was observed with A. neomexicana, A. tesselata, and A. exsanguis at one site north of the Canadian River and two sites south of the river. At Fort Sumner, we studied A. neomexicana at two sites where it was syntopic with A. tesselata E and A. sexlineata viridis. We identified 15 lizards from three sites at Conchas Lake as hybrids of A. neomexicana 3 A. sexlineata viridis. Most of these hybrids were found in either patchy or weedy chronically disturbed habitats in which the parental forms were forced into unusually close syntopic relationships. Hybrids between these parental forms were collected in each year from 2000-2003 and represented a minimum of four and a maximum of five generations. Although hybrids of A. neomexicana x A. sexlineata viridis were characterized by distinctive color patterns, all were rather similar to maternal parent A. neomexicana, but with modifications resulting from the genetic contribution of its paternal parent A. sexlineata viridis. All specimens identified as hybrids by color pattern also possessed meristic characters that distinguished them from both parental forms. Univariate and multivariate analyses of scutellation also revealed evidence of the genetic effects of the parental species on the hybrids. One live hybrid male of A. neomexicana x A. sexlineata viridis was collected at Conchas Lake. The hybrid (American Museum of Natural History R-151739) was a triploid (3n = 69) including the complete diploid complement of A. neomexicana (= A. tigris marmorata x A. inornata) plus a second haploid complement of sexlineata group chromosomes. Karyotypically, in all details this triploid appeared to be an F1 hybrid of A. neomexicana x A. sexlineata viridis. This confirmed hybrid possessed a similar array of color pattern and scutellation characters observed in the other individuals of presumptive A. neomexicana x A. sexlineata viridis from Conchas Lake. Of the 23 allozyme loci analyzed, 9 showed no allelic variation among the individuals of the parental taxa and the hybrid examined; however, 12 loci were particularly informative for identifying the hybrid and its parental species. For most of these loci, the suspected hybrid (based on morphology and triploid karyotype) had electrophoretic banding patterns consistent with a triploid bearing a combination of alleles that included the two found in diploid A. neomexicana plus a third allele from the local A. sexlineata viridis. This is consistent with a cloned A. neomexicana ovum having been fertilized by a haploid A. sexlineata viridis spermatozoan. We present the first evidence of perennial hybridization in Aspidoscelis between a parthenogen and a species other than a progenitor. However, we found no evidence that occasional hybridization between A. neomexicana and A. sexlineata viridis has had a significant negative effect on either of these species at Conchas Lake.