Homoploid hybrid speciation is the origin of a hybrid species without change in chromosome number. Although currently thought to be a rare form of speciation, especially relative to the more common allopolyploid hybrid speciation, it is feasible that many examples of homoploid hybrid species will be discovered in the future now that genetic resources are readily available for testing their occurrence. In this review, we focus on the speed of homoploid hybrid speciation, the importance of ecological and spatial isolation in the process, and the nature of genetic changes that occur in a new hybrid during its origin and establishment in the wild. With reference mainly to the extensive work carried out on homoploid hybrid species of Helianthus, and to our own work on the very recently originated diploid hybrid species Senecio squalidus, we review evidence showing: (1) that new fertile homoploid hybrid species can originate very quickly, although a longer period is likely to be required before the species becomes fully stabilized both genomically and phenotypically; (2) ecological divergence of the hybrid species from its parents is key to successful establishment, and that this can occur even in the absence of post­zygotic isolation caused by chromosomal and/or genetic sterility barriers; (3) transgressive changes in phenotypic traits and gene expression are of great importance in adapting homoploid hybrid species to habitats that are ecologically and spatially divergent from those of the parents; (4) adaptive differences distinguishing a homoploid hybrid species from its parental species are likely to be maintained in the face of parental gene flow, and evolve in concert across populations representing multiple origins of the species; (5) in the absence of parental gene flow, i.e., under conditions of geographical isolation, rapid genetic divergence of the hybrid species is likely to be enhanced due to the combined effects of founder events, genetic drift and selection.

Cryoconite is a microbe-mineral aggregate which darkens the ice surface of glaciers. Microbial process and marker gene PCR-dependent measurements reveal active and diverse cryoconite microbial communities on polar glaciers. Here, we provide the first report of a cryoconite metagenome and culture-independent study of alpine cryoconite microbial diversity. We assembled 1.2 Gbp of metagenomic DNA sequenced using an Illumina HiScanSQ from cryoconite holes across the ablation zone of Rotmoosferner in the Austrian Alps. The metagenome revealed a bacterially-dominated community, with Proteobacteria (62% of bacterialassigned contigs) and Bacteroidetes (14%) considerably more abundant than Cyanobacteria (2.5%). Streptophyte DNA dominated the eukaryotic metagenome. Functional genes linked to N, Fe, S and P cycling illustrated an acquisitive trend and a nitrogen cycle based upon efficient ammonia recycling. A comparison of 32 metagenome datasets revealed a similarity in functional profiles between the cryoconite and metagenomes characterized from other cold microbe-mineral aggregates. Overall, the metagenomic snapshot reveals the cryoconite ecosystem of this alpine glacier as dependent on scavenging carbon and nutrients from allochthonous sources, in particular mosses transported by wind from ice-marginal habitats, consistent with net heterotrophy indicated by productivity measurements. A transition from singular snapshots of cryoconite metagenomes to comparative analyses is advocated.

The CFQ-R found differences between inpatients and outpatients and between younger and older paediatric patients with CF, and between parent and child perceptions of QOL.

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