JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. American Society of Ichthyologists and Herpetologists (ASIH) is collaborating with JSTOR to digitize, preserve and extend access to Copeia. Samples of Liolaemus monticola monticola from seventeen localities in the montane Andean range in central Chile showed great intra-and interpopulational karyotypic variation and were grouped into two allopatric races; these included a southern race with 2n = 34, and a northern race with 2n = 38-40. The chromosomal differences in number and morphology could be explained by centric fissions, pericentric inversion or short-arm heterochromatic additions, and increase in microchromosomes. The distribution and number of chiasmata were statistically different between the two chromosomal races. The two chromosomal races were separated by the Maipo and Yeso rivers, which appeared to function as barriers to gene flow between these two races.Hybridization from secondary contact between these chromosomal races was found in a narrow zone that resulted from lizard migration across a road bridge over the Yeso river. Meiotic irregularities at diakinesis and metaphase II were present in the interchromosomal hybrids, suggesting that the chromosomal differences between the hybridizing populations might decrease fitness in heterozygotes. The origin of the chromosomal rearrangements and of the meiotic recombination patterns resulting from chromosomal heterozygosity are discussed with respect to the evolution of this complex in central Chile.Ejemplares de Liolaemus monticola monticola, procedentes de 17 localidades del rango andino de Chile Central, presentaron una gran variaci6n cromosomica intra-e interpoblacional, permitiendo reconocer dos razas cromosomicas y alopaitricas a saber: Raza Sur con un nuimero cromosomico diploide 2n = 34 y Raza Norte con un 2n = 38 a 40. Las diferencias en el nuimero, forma y tamafio de los cromosomas, pueden ser explicadas por fisiones centricas, inversiones pericentricas o adicion de heterocromatina e incremento de microcromosomas. La distribucion y el nuimero de quiasmas son estadisticamente diferentes entre estas dos razas cromos6micas. Ambas razas estan segregadas por el rio Maipo y el rio Yeso, los que funcionan como barrera al flujo genico entre ambas.Se encontro una estrecha zona de hibridacion interracial, producto de un contacto secundario entre estas razas cromosomicas, resultado de la migracion de lagartijas a traves de un puente sobre el rio Yeso. Las irregularidades meioticas encontradas en las diaquinesis y Metafases II de los hibridos entre ambas razas, sugieren que en los heterocigotos, las diferencias cromosomicas parentales, disminuirian la adecuacion biologica. Se discute acerca del origen de los rearreglos cro...
Liolaemus monticola is a mountain lizard species, with a widespread distribution from central Chile that displays several highly polymorphic chromosomal races. Our study determined the phylogeographic structuring and relationships among three chromosomal races of L. monticola in Chile. Mitochondrial DNA (mtDNA) sequences of the cytochrome b gene were examined using the following phylogenetic methods: maximum parsimony, maximum likelihood, Bayesian inference and nested clade phylogeographic analyses (NCPAs). These methods revealed two major monophyletic clades (north and south) in the L. monticola species, with non-overlapping geographical locations separated by the Maipo and Yeso rivers (except one hybrid, from a zone of secondary contact). The NCPA showed that a past fragmentation process likely resulted in the separation of the two clades. The southern clade includes all samples of the ÔSouthern, 2n ¼ 34Õ race; the northern clade is comprised of all remaining derived chromosomal races: the ÔNorthern, 2n ¼ 38-40 and the Multiple Fission, 2n ¼ 42-44Õ races. Our results support the hypothesis of a geographical and genetic split resulting from allopatric processes caused by riparian barriers acting over a long time period. The inferred biogeographical scenario shows that populations have moved from the south to the north using the Andean mountains as the primary corridor for dispersal.
Univariate and multivariate statistical analyses of 39 meristic characters recorded for 12 samples of the lizard Liolaemus monticola were used to compare geographical variation in morphology with chromosomal races north and south of the Maipo River in central Chile. This extends a previous morphological study in the Andes Range and confirms that the Maipo River is a biogeographical barrier that also separates chromosomal races in the Coast Range. The phenetic variation among samples is sufficient to differentiate the chromosomal races, and also distinguishes populations of the Coast Range from those of the Andes within chromosomal races. A possible historical sequence of events that accounts for the pattern of morphological differentiation is advanced.
Univariate and multivariate statistical analyses of 28 meristic characters recorded for 19 samples of the lizard Liolaemus monticola monticola were used to compare geographical variation in morphology with chromosomal races north and south of the Maipo River, and north and south of the Aconcagua River in central Chile, plus some affluent. This extends a previous morphological study that confirmed that the Maipo River is a biogeographical barrier that separates chromosomal races "Southern, 2n=34" and "Northern, 2n=38-40", and reports for the first time the importance of the Aconcagua River as another biogeographical barrier between the chromosomal races "Northern, 2n=38-40" and the "Multiple Fission, 2n=42-44". The phenetic variation among samples is sufficient to differentiate the three chromosomal races, and also distinguishes populations within the chromosomal races such as the ones separated by the Colorado River, an affluent of the Aconcagua River. A possible historical sequence of events that accounts for the pattern of morphological differentiation is advanced.
The delimitation of species is a major issue in systematic biology and has been a re-emerging discipline in the last decade. A number of studies have shown that the use of multiple data sets is critical for the identification of cryptic species, particularly in groups with complex evolutionary histories. Liolaemus monticola is a montane lizard species distributed in central Chile (32°-42°S), with four described subspecies in a latitudinal gradient from north to south: L. m. monticola, L. m. chillanensis, L. monticola ssp. and L. m. villaricensis. In order to test the systematic status and phylogenetic relationships of the taxa included in the L. monticola group, we analysed morphological (morphometric and meristic) and molecular (allozyme and mitochondrial DNA) data sets. The results of the morphological analyses showed that meristic variables correctly assigned individuals with higher accuracy than did morphometric characters. The results of the analyses of allozyme data revealed eight diagnostic loci that are evidence for significant differences among the four L. monticola subspecies. Phylogenetic analyses with mitochondrial DNA data, including additional species, showed that the L. monticola group is polyphyletic. We postulate that the four current subspecies represent independent evolutionary lineages and must be raised to the specific level as L. monticola, L. chillanensis and L. villaricensis. The taxonomic status of the unnamed L. monticola ssp. remains unresolved, although we provide a preliminary proposal.
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