[Download] "Un Discurso Esclavista de la Ilustracion: La Trata Negrera en El Proyecto Plantocratico de Louis Balbes des Berton, Duque de Crillon y Mahon" by Endangered Species Update * Book PDF Kindle ePub Free
eBook details
- Title: Un Discurso Esclavista de la Ilustracion: La Trata Negrera en El Proyecto Plantocratico de Louis Balbes des Berton, Duque de Crillon y Mahon
- Author : Endangered Species Update
- Release Date : January 01, 2008
- Genre: Science & Nature,Books,Life Sciences,
- Pages : * pages
- Size : 66 KB
Description
Defining taxonomic units that are significant in terms of their evolutionary potential and history is crucial for an accurate understanding of biological diversity. To clearly and operationally define what these units are is fundamental in conservation biology as well because they are the basis for any decision about priorities, regardless of the criteria for setting these priorities. Without carefully assessing biological diversity, we will not be able to understand what we have, what can still be saved and what might be most urgent to save. Assessing biological diversity has been revolutionised by tools such as DNA barcoding, the idea that a short stretch of DNA sequence can be used as a barcode to identify and discover taxa. It is simple, fast, and relatively cheap. However, by definition, it only focuses on the genotype. Relying on a single point of comparison, such as mitochondrial DNA (mtDNA), for assessing taxonomic differences poses serious risk of underestimating biological diversity (e.g., Will & Rubinoff 2004; Desalle et al. 2005; Rubinoff 2006; Elias at al. 2007; Trewick 2008). For example, the short sequence of mtDNA used in barcoding represents a tiny fraction of the whole genome, and analysis of nuclear DNA from the same species may give a very different picture to that obtained from mtDNA, as the two do not share the same mechanisms of inheritance and have different modes of evolution (Rubinoff 2006). However seductive the genomic techniques seem, measuring phenotypic diversity remains essential because the phenotype reflects historical processes and plastic responses to the environment. Heritable variation in phenotypes is the expression of adaptive characters "shaped by gene flow, genetic drift and natural selection" (Crandall et al. 2000) and provides information on the evolutionary processes that lead to different adaptations. Plasticity is non-heritable but still important as it might increase evolvability by accelerating the speed by which populations can move between adaptive peaks (Borenstein et al. 2006). Preserving these processes by conserving phenotypic diversity retains evolutionary potential.