RESUMO
Comparative whole-genome analyses hold great power to illuminate commonalities and differences in the evolution of related species that share similar ecologies. The mustelid subfamily Lutrinae includes 13 currently recognized extant species of otters,1-5 a semiaquatic group whose evolutionary history is incompletely understood. We assembled a dataset comprising 24 genomes from all living otter species, 14 of which were newly sequenced. We used this dataset to infer phylogenetic relationships and divergence times, to characterize patterns of genome-wide genealogical discordance, and to investigate demographic history and current genomic diversity. We found that genera Lutra, Aonyx, Amblonyx, and Lutrogale form a coherent clade that should be synonymized under Lutra, simplifying the taxonomic structure of the subfamily. The poorly known tropical African Aonyx congicus and the more widespread Aonyx capensis were found to be reciprocally monophyletic (having diverged 440,000 years ago), supporting the validity of the former as a distinct species. We observed variable changes in effective population sizes over time among otters within and among continents, although several species showed similar trends of expansions and declines during the last 100,000 years. This has led to different levels of genomic diversity assessed by overall heterozygosity, genome-wide SNV density, and run of homozygosity burden. Interestingly, there were cases in which diversity metrics were consistent with the current threat status (mostly based on census size), highlighting the potential of genomic data for conservation assessment. Overall, our results shed light on otter evolutionary history and provide a framework for further in-depth comparative genomic studies targeting this group.
Assuntos
Lontras , Animais , Sequência de Bases , Lontras/genética , FilogeniaRESUMO
Domesticated maize evolved from wild teosinte under human influences in Mexico beginning around 9000 years before the present (yr B.P.), traversed Central America by ~7500 yr B.P., and spread into South America by ~6500 yr B.P. Landrace and archaeological maize genomes from South America suggest that the ancestral population to South American maize was brought out of the domestication center in Mexico and became isolated from the wild teosinte gene pool before traits of domesticated maize were fixed. Deeply structured lineages then evolved within South America out of this partially domesticated progenitor population. Genomic, linguistic, archaeological, and paleoecological data suggest that the southwestern Amazon was a secondary improvement center for partially domesticated maize. Multiple waves of human-mediated dispersal are responsible for the diversity and biogeography of modern South American maize.
Assuntos
Evolução Biológica , Domesticação , Zea mays/classificação , Zea mays/genética , Genoma de Planta , Modelos Biológicos , Mutação , Filogenia , América do SulRESUMO
INTRODUCTION: There is limited information available on the natural history and prognosis of keloid scars. AIM: To evaluate how keloid scars behave over time to develop prognostic information for patients. MATERIALS AND METHODS: 34 patients in Manchester and Barbados (average age 34 years) yielding 126 keloids completed questionnaires about their lesions. RESULTS: 46 keloids (37%) were described by patients as resolved, meaning they were satisfactory in appearance, not symptomatic and not requiring treatment. In each case the scar remained visible. 36 (29%) lesions resolved following treatment. Ten (8%) resolved spontaneously. The median number of years to resolution with treatment was 11.4 and to spontaneous resolution was 5, this difference was statistically significant (p < 0.05). The median number of years since resolution with treatment was 3 and since spontaneous resolution was 18, this difference was statistically significant (p < 0.0001). Seventeen lesions (13%) were resolving with treatment. 63 (50%) remained active. Overall the median number of years scars persisted was 15. CONCLUSION: Keloids never completely disappear to leave skin with normal texture, however they can resolve (flatten and soften) so they no longer burden patients in approximately one third of cases. Scars resolving spontaneously do so early in the disease. Those that don't may resolve after many years of treatment. This data can provide prognostic information to patients, and a baseline for future therapeutic trials.