Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Islands in the sky: the impact of Pleistocene climate cycles on biodiversity. | Journal of Biology BioMed Central Minireview Islands in the sky the impact of Pleistocene climate cycles on biodiversity Allan J Baker Address Department of Natural History Royal Ontario Museum Toronto Ontario Canada M5S 2C6 and Department of Ecology and Evolutionary Biology University of Toronto Toronto Ontario Canada M5S 3B2. Email allanb@ Published 3 November 2008 Journal of Biology 2008 7 32 doi jbiol90 The electronic version of this article is the complete one and can be found online at http content 7 9 32 2008 BioMed Central Ltd Abstract Genetic studies of organisms based on coalescent modeling and paleoenvironmental data including a new study in BMC Biology of Mexican jays in the sky islands of Arizona and northern Mexico show that populations differentiated in multiple refugia during and after glacial cycles. The general cooling of the world s climate that began in the Tertiary and culminated in the Pleistocene glacial cycles from about million years ago attracted the attention of evolutionary biologists because of its possible effect in changing species distributions and thus on the speciation of organisms. The role of these climatic fluctuations on speciation has been much debated. At one end of the debate some researchers argued that the cooling suppressed or slowed speciation as leading-edge waves of species populations repeatedly colonized deglaciated regions in the interglacial periods 1 2 . This form of repeated colonization of genetically similar individuals from the same source populations can prevent genetic differentiation required for speciation. Others thought that the cooling and the barriers of ice that divided up populations increased the rate of speciation in an extreme example of this view Ernst Mayr wrote in his classic 1970 book 3 that Evolutionists agree on the overwhelming importance of Pleistocene barriers in the speciation of temperate zone animals . Data from studies of North American songbirds have .
