Hybridization Among the Subspecies of the Plethodontid Salamander Ensatina Eschscholtzi PDF Download

Author: Charles William Brown
Publisher:
ISBN: 9780520094420
Category : Ensatina eschscholtzi
Languages : en
Pages : 56

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Author: Charles W. Brown
Publisher:
ISBN: 9780598178459
Category :
Languages : en
Pages : 57

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The analysis of interactions between lineages at varying levels of genetic divergence can provide insights into the process of speciation through the accumulation of incompatible mutations. Ring species, and especially the Ensatina eschscholtzii system exemplify this approach. The plethodontid salamanders Ensatina eschscholtzii xanthoptica and Ensatina eschscholtzii platensis hybridize in the Central Sierran foothills of California. We compared the genetic structure across two transects (southern and northern Calaveras Co.), one of which was re-sampled over 20 years, and examined diagnostic molecular markers (eight allozyme loci and mitochondrial DNA) and a diagnostic quantitative trait (color pattern). Key results across all studies were: (i) cline centers for all markers were coincident and the zones were narrow, with width estimates of 730m to 2000m; (ii) cline centers at the northern Calaveras transect were coincident between 1981 and 2001, demonstrating repeatability over 5 generations; (iii) there are very few if any putative F1's, but a relatively high number of backcrossed individuals (57-86 percent) in the central portion of transects; (iv) we found substantial linkage disequilibrium in all three studies and strong heterozygote deficit both in northern Calaveras, in 2001, and southern Calaveras. Both linkage disequilibrium and heterozygote deficit show maximum values near the center of the zones (R and Fis, approx. equal to 0.5). Using estimates of cline width and dispersal, we infer strong selection against hybrids (s* approx. equal to 46-75 percent). This is sufficient to promote accumulation of differences at loci that are neutral or under divergent selection, but would still allow for introgression of adaptive alleles. The evidence for strong, but incomplete isolation across this centrally located contact is consistent with theory suggesting a gradual increase in postzygotic incompatibility between allopatric populations subject to divergent selection and reinforces the value of Ensatina as a system for the study of divergence and speciation at multiple stages.

Author: U.S. Fish and Wildlife Service
Publisher:
ISBN:
Category : Animals
Languages : en
Pages : 826

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Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 470

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Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 446

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Author: L. Lee Grismer
Publisher: Univ of California Press
ISBN: 0520925203
Category : Science
Languages : en
Pages : 416

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The Baja California peninsula is home to many forms of life found nowhere else on earth. This, combined with the peninsula's rugged and inaccessible terrain, has made the area one of the last true biological frontiers of North America. L. Lee Grismer is not only the foremost authority on the amphibians and reptiles of Baja California, but also an outstanding photographer. He has produced the most comprehensive work on the herpetofauna of the peninsula and its islands ever published. With its stunning color images, detailed accounts of many little-known species, and descriptions of the region's diverse environment, this is the definitive guide to the amphibians and reptiles of a fascinating and remote region. The culmination of Grismer's quarter century of fieldwork on the Baja peninsula and his exploration of more than one hundred of its islands in the Pacific Ocean and the Sea of Cortés, this book gives information on the identification, distribution, natural history, and taxonomy of each species of amphibian and reptile found there. Preliminary accounts of the life history of many of the salamanders, frogs, toads, turtles, lizards, and snakes are reported here for the first time, and several species that were almost unknown to science are illustrated in full color. The book also contains new data on species distribution and on the effect of the isolated landscape of the peninsula and its islands on the evolutionary process. Much of the information gathered here is presented in biogeographical overviews that consider the extremely varied environments of Baja California in both a contemporary and a historical framework. An original and important contribution to science, this book will generate further research for years to come as it becomes a benchmark reference for both professionals and amateurs.

Author:
Publisher: Academic Press
ISBN: 0128004266
Category : Science
Languages : en
Pages : 2138

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Encyclopedia of Evolutionary Biology, Four Volume Set is the definitive go-to reference in the field of evolutionary biology. It provides a fully comprehensive review of the field in an easy to search structure. Under the collective leadership of fifteen distinguished section editors, it is comprised of articles written by leading experts in the field, providing a full review of the current status of each topic. The articles are up-to-date and fully illustrated with in-text references that allow readers to easily access primary literature. While all entries are authoritative and valuable to those with advanced understanding of evolutionary biology, they are also intended to be accessible to both advanced undergraduate and graduate students. Broad topics include the history of evolutionary biology, population genetics, quantitative genetics; speciation, life history evolution, evolution of sex and mating systems, evolutionary biogeography, evolutionary developmental biology, molecular and genome evolution, coevolution, phylogenetic methods, microbial evolution, diversification of plants and fungi, diversification of animals, and applied evolution. Presents fully comprehensive content, allowing easy access to fundamental information and links to primary research Contains concise articles by leading experts in the field that ensures current coverage of each topic Provides ancillary learning tools like tables, illustrations, and multimedia features to assist with the comprehension process

Author: Benedetto Lanza
Publisher: Museo Reg. Scienze Nat. Torino
ISBN:
Category : Nature
Languages : en
Pages : 376

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Author:
Publisher:
ISBN:
Category : Amphibians
Languages : en
Pages : 448

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Relationships between wildlife and their habitats are examined in a series of matrixes, species narratives, and distribution maps.