Hybridization in the Ensatina Ring Species, Strong Selection Against Hybrids at a Hybrid Zone in the Ensatina Ring Species Complex and Its Evolutionary Implications PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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: Jerry A. Coyne Publisher: OUP Oxford ISBN: 019164384X Category : Science Languages : en Pages : 416
Book Description
For all the discussion in the media about creationism and 'Intelligent Design', virtually nothing has been said about the evidence in question - the evidence for evolution by natural selection. Yet, as this succinct and important book shows, that evidence is vast, varied, and magnificent, and drawn from many disparate fields of science. The very latest research is uncovering a stream of evidence revealing evolution in action - from the actual observation of a species splitting into two, to new fossil discoveries, to the deciphering of the evidence stored in our genome. Why Evolution is True weaves together the many threads of modern work in genetics, palaeontology, geology, molecular biology, anatomy, and development to demonstrate the 'indelible stamp' of the processes first proposed by Darwin. It is a crisp, lucid, and accessible statement that will leave no one with an open mind in any doubt about the truth of evolution.
Author: Gary C. Howard Publisher: CRC Press ISBN: 0429946104 Category : Nature Languages : en Pages : 180
Book Description
San Francisco Bay is a shallow estuary surrounded by a large population center. The forces that built it began with plate tectonics and involved the collision of the Pacific and North American plates and the subduction of the Juan de Fuka plate. Changes in the climate resulting from the last ice age yielded lower and then higher sea levels. Human activity influenced the Bay. Gold mining during the California gold rush sent masses of slit into the Bay. Humans have also built several major cities and filled significant parts of the Bay. This book describes the natural history and evolution of the SF Bay Area over the last 50 million years through the present and into the future. Key selling features: Summarizes a complex geological, geographical and ecological history Reviews how the San Francisco Bay has changed and will likely change in the future Examines the different roles and various drivers of Bay ecosystem function Includes the role of humans - both first peoples and modern populations - on the Bay Explores San Francisco Bay as an example of general bay ecolgical and environmental issues
Author: Richard C. Bruce Publisher: Springer Science & Business Media ISBN: 9780306463044 Category : Medical Languages : en Pages : 506
Book Description
This volume offers a state-of-the-art overview of plethodontid salamanders. Readers will find the best current understanding of many aspects of the evolution, systematics, development, morphology, life history, ecology, and field methodology of these animals.
Author: David L. Jameson Publisher: ISBN: Category : Evolution Languages : en Pages : 360
Book Description
The nature of populations, races, subspecies, and species. Genetic basis of isolation. Origin of isolation - theoretical. Origin of isolation - experimental. The nature of the speciation process.
Author: Andrew P. Hendry Publisher: Springer Science & Business Media ISBN: 9401005850 Category : Science Languages : en Pages : 528
Book Description
From guppies to Galapagos finches and from adaptive landscapes to haldanes, this compilation of contributed works provides reviews, perspectives, theoretical models, statistical developments, and empirical demonstrations exploring the tempo and mode of microevolution on contemporary to geological time scales. New developments, and reviews, of classic and novel empirical systems demonstrate the strength and diversity of evolutionary processes producing biodiversity within species. Perspectives and theoretical insights expand these empirical observations to explore patterns and mechanisms of microevolution, methods for its quantification, and implications for the evolution of biodiversity on other scales. This diverse assemblage of manuscripts is aimed at professionals, graduate students, and advanced undergraduates who desire a timely synthesis of current knowledge, an illustration of exciting new directions, and a springboard for future investigations in the study of microevolution in the wild.
Author: Trevor Price Publisher: Roberts ISBN: Category : Nature Languages : en Pages : 484
Book Description
In Speciation in Birds, Trevor Price, a University of Chicago professor and leading expert in the field, has written the most authoritative and modern synthesis on the subject to date. In clear and engaging prose and through beautiful illustrations, Price shows us why the field is as exciting and vibrant as ever. He evaluates the roles of natural selection and sexual selection. He asks how speciation contributes to some of the great patterns in species diversity such as the large number of species in the tropics, and the many endemic species on isolated islands. Throughout the book, Price emphasizes the integration of behavior, ecology, and genetics.
Author: Daniel J. Howard Publisher: Oxford University Press, USA ISBN: 9780195109016 Category : Science Languages : en Pages : 486
Book Description
Speciation is one of the great themes of evolutionary biology. It is the process through which new species are born and diversity generated. Yet for many years our understanding of the process consisted of little more than a perception that if populations are isolated geographically, they will diverge genetically and may come to form new species. This situation began to change in the 1960s as an increasing number of biologists challenged the exclusivity of allopatric speciation and began to probe more deeply into the actual process by which divergence occurs and reproductive isolation is acquired. This focus on process led to many new insights, but numerous questions remain and speciation is now one of the most dynamic areas of research in modern evolutionary biology. This volume presents the newest research findings on speciation bringing readers up to day on species concepts, modes of speciation, and the nature of reproductive barriers. It also discusses the forces that drive divergence of populations, the genetic control of reproductive isolation, and the role played by hybrid zones and hybridization in speciation.
Author: Igor Pavlinov Publisher: BoD – Books on Demand ISBN: 953510957X Category : Science Languages : en Pages : 293
Book Description
The book includes collection of theoretical papers dealing with the species problem, which is among most fundamental issues in biology. The principal topics are: consideration of the species problem from the standpoint of modern non-classical science paradigm, with emphasis on its conceptual status presuming its analysis within certain conceptual framework; evolutionary emergence of the species as discrete unit of certain level of generality; epistemological consideration of the species as a particular explanatory hypotheses, with respective revised concepts of biodiversity and conservation; considerations of evolutionary and phylogenomic species concepts as candidates for the universal one; re-appraisal of the biological species concept based on the "friend-foe" recognition system; species delimitation approach using multi-locus coalescent-based method; a re-consideration of the Darwin's species concept.
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Author: Jerry A. Coyne
Author: Gary C. Howard
Author: Richard C. Bruce
Author: David L. Jameson
Author: Robert Cyril Stebbins
Author: Andrew P. Hendry
Author: Trevor Price
Author: Daniel J. Howard
Author: Igor Pavlinov