4 resultados para colonialism - history - Oceania - Cook Islands

em Université de Lausanne, Switzerland


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An earlier study revealed the strong phylogeographical structure of the lesser white-toothed shrew (Crocidura suaveolens group) within the northern Palaearctic. Here, we aim to reconstruct the colonization history of Mediterranean islands and to clarify the biogeography and phylogeographical relationships of the poorly documented Middle East region with the northern Palaearctic. We performed analyses on 998-bp-long haplotypes of the mitochondrial cytochrome b gene of 143 samples collected around the Mediterranean basin, including islands and the Middle East. The analyses suggest that the Cypriot shrew belongs to the rare group of relict insular Pleistocene mammal taxa that have survived to the present day. In contrast, the Cretan, Corsican and Menorcan populations were independently introduced from the Middle East during the Holocene. The phylogeographical structure of this temperate Palaearctic species within the Middle East appears to be complex and rich in diversity, probably reflecting fragmentation of the area by numerous mountain chains. Four deeply divergent clades of the C. suaveolens group occur in the area, meaning that a hypothetical contact zone remains to be located in central western Iran.

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The karyotype, morphology and biology of Crocidura from Fuerteventura (Canary Islands) are described. The species has a diploid chromosome number of 2n = 36, thus differing from all other species of the genus. A detailed morphological comparison of the shrews from Fuerteventura, Lanzarote and other islets with C. russula from Morocco revealed specific characters for both taxa. Differences were also observed in biological parameters. It is concluded that the Canary Island populations of Crocidura form a biological species which is consequently named Crocidura canariensis sp. nov.

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This article explores possible histories of plant exchanges and plant naming tied to the slave trade between East Africa, Madagascar and the Mascarene Islands. The subsequent 'marronnage' of slaves on these islands - their escape from captivity, sometimes to live in mountain hideouts - continues to inspire cultural references. Inspired by the use of the adjective 'marron/marronne' for a number of plants on Reunion Island, we compile evidence of plant exchanges and plant naming from ecological records, historical accounts and the use of descriptive, emotive or symbolic vernacular names as clues for deepening our knowledge of historical societies and environments. The evidence from the Mascarenes opens a window into the role of the African diaspora in plant introduction, diffusion, domestication and cultivation. We document that maroons relied on a variety of wild, escaped and cultivated plants for their subsistence. We also highlight the role of marronnage in the popular and literary imaginary, with the result that many plants are named 'marron/marrone' in a metaphorical sense. Finally, we identify a few plants that may have been transported, cultivated, or encouraged in one way or another by maroons. Along the way, we reflect on the pitfalls and opportunities of such interdisciplinary work.

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New genes contribute substantially to adaptive evolutionary innovation, but the functional evolution of new mammalian genes has been little explored at a broad scale. Previous work established mRNA-derived gene duplicates, known as retrocopies, as models for the study of new gene origination. Here we combine mammalian transcriptomic and epigenomic data to unveil the processes underlying the evolution of stripped-down retrocopies into complex new genes. We show that although some robustly expressed retrocopies are transcribed from preexisting promoters, most evolved new promoters from scratch or recruited proto-promoters in their genomic vicinity. In particular, many retrocopy promoters emerged from ancestral enhancers (or bivalent regulatory elements) or are located in CpG islands not associated with other genes. We detected 88-280 selectively preserved retrocopies per mammalian species, illustrating that these mechanisms facilitated the birth of many functional retrogenes during mammalian evolution. The regulatory evolution of originally monoexonic retrocopies was frequently accompanied by exon gain, which facilitated co-option of distant promoters and allowed expression of alternative isoforms. While young retrogenes are often initially expressed in the testis, increased regulatory and structural complexities allowed retrogenes to functionally diversify and evolve somatic organ functions, sometimes as complex as those of their parents. Thus, some retrogenes evolved the capacity to temporarily substitute for their parents during the process of male meiotic X inactivation, while others rendered parental functions superfluous, allowing for parental gene loss. Overall, our reconstruction of the "life history" of mammalian retrogenes highlights retroposition as a general model for understanding new gene birth and functional evolution.