Reticulate evolution: frequent introgressive hybridization among chinese hares (genus lepus) revealed by analyses of multiple mitochondrial and nuclear DNA loci

<p>Abstract</p> <p>Background</p> <p>Interspecific hybridization may lead to the introgression of genes and genomes across species barriers and contribute to a reticulate evolutionary pattern and thus taxonomic uncertainties. Since several previous studies have demonstrated that introgressive hybridization has occurred among some species within <it>Lepus</it>, therefore it is possible that introgressive hybridization events also occur among Chinese <it>Lepus </it>species and contribute to the current taxonomic confusion.</p> <p>Results</p> <p>Data from four mtDNA genes, from 116 individuals, and one nuclear gene, from 119 individuals, provides the first evidence of frequent introgression events via historical and recent interspecific hybridizations among six Chinese <it>Lepus </it>species. Remarkably, the mtDNA of <it>L. mandshuricus </it>was completely replaced by mtDNA from <it>L. timidus </it>and <it>L. sinensis</it>. Analysis of the nuclear DNA sequence revealed a high proportion of heterozygous genotypes containing alleles from two divergent clades and that several haplotypes were shared among species, suggesting repeated and recent introgression. Furthermore, results from the present analyses suggest that Chinese hares belong to eight species.</p> <p>Conclusion</p> <p>This study provides a framework for understanding the patterns of speciation and the taxonomy of this clade. The existence of morphological intermediates and atypical mitochondrial gene genealogies resulting from frequent hybridization events likely contribute to the current taxonomic confusion of Chinese hares. The present study also demonstrated that nuclear gene sequence could offer a powerful complementary data set with mtDNA in tracing a complete evolutionary history of recently diverged species.</p

The declining trend in sulfur dioxide emissions: Implications for allowance prices

In this paper, we find that sulfur dioxide (SO,) emissions by electric utilities declined from 1985 to 1993 for reasons largely unrelated to the emission reduction mandate of Title IV of the 1990 Clean Air Act Amendments. The principal reason appears to be the decline in rail rates for low-sulfur western coal delivered to higher-sulfur coal-fired plants in the Midwest. Consequently, there is less sulfur to be removed to meet the Title IV cap on aggregate SO, emissions, and the cost of compliance and price of allowances can be expected to be less than would otherwise have been the case. (C) 1998 Academic Press

Over-Allocation or Abatement? A Preliminary Analysis of the EU ETS Based on the 2005–06 Emissions Data

Climate policy, European Union Emissions Trading Scheme, Data analysis, C81, H41, O13, Q54, Q58,

An interim evaluation of sulfur dioxide emissions trading

This paper summarizes recent empirical research on compliance costs and strategies and on permit market performance under the U.S. acid rain program, the first large-scale, long-term program to use tradeable emissions permits to control pollution. An efficient market for emissions permits developed in a few years, and this program more than achieved its early goals on time, and it cost less than had been projected. Because of expectation errors, however, investment was excessive, and permit prices substantially understate abatement costs. The tradeable permits approach has worked well, but it is not a miracle cure for environmental problems. Coauthors are Paul L. Joskow, A. Denny Ellerman, Juan Pablo Montero, and Elizabeth M. Bailey